FIFTH EDITION

Edited by

Jeffrey McCullough

University of Minnesota

Minneapolis, MN, USA

Jeffrey McCullough MD

For centuries, blood has been considered to have mystical properties and has been associated with vitality. In ancient times, bathing in or drinking the blood of the strong was thought to invigorate the weak. For instance, among Ancient Romans it was customary to rush into the arena to drink the blood of dying gladiators [1]; among others, to drink or bathe in blood was thought to cure a variety of ailments [2]. Bleeding was practiced to let out bad blood and restore the balance of humors, thus hopefully returning the patient to health.

It is not known when and by whom the idea of transfusing blood was developed. It is said that the first transfusion was given to Pope Innocent VIII in 1492. According to this legend, the Pope was given the blood of three boys, whose lives were thus sacrificed in vain [1, 3] because the attempts did not save the Pope. In another version of the story, the blood was intended to be used in a tonic for the Pope, which he refused, thus sparing the boys’ lives [2]. Ironically, the concept of transfusion blood from younger donors to revitalize older individuals has reappeared recently, although without any scientific background or basis.

Others to whom the idea for blood transfusion is attributed include Hieronymus Cardanus (1501–1576) and Magnus Pegelius. Little is known about Cardanus, but Pegelius was a professor at Rostock, Germany, who supposedly published a book describing the idea and theory of transfusion [1]. It can be substantiated that Andreas Libavius (1546–1616) proposed blood transfusion in 1615 when he wrote:

Let there be a young man, robust, full of spirituous blood, and also an old man, thin, emaciated, his strength exhausted, hardly able to retain his soul. Let the performer of the operation have two silver tubes fitting into each other. Let him enter the artery of the young man, and put into it one of the tubes, fastening it in. Let him immediately open the artery of the old man and put the female tube into it, and then the two tubes being joined together, the hot and spirituous blood of the young man will pour into the old one as it were from a fountain of life, and all of this weakness will be dispelled [1].

Despite these possibilities, it also seems unlikely that the concept of transfusing blood could have developed before William Harvey’s description of the circulation in 1616. Despite Harvey’s description of the circulatory system, there is no evidence that he considered blood transfusion. However, the concept of the “circulation” may have preceded Harvey’s publication. For instance, Andrea Cesalpino (1519–1603), an Italian, used the expression “circulation” and proposed that fine vessels (capillaries) connected the arterial and venous systems [1, 4].

A number of the major developments that led to the beginning of blood transfusion occurred during the mid‐1600s [1]. In 1656, Christopher Wren, assisted by Robert Boyle, developed techniques to isolate veins in dogs and carried out many studies of the effects of injecting substances into the dogs. It is not clear whether Wren ever carried out blood transfusion between animals. The first successful transfusion from one animal to another probably was done by Richard Lower [1, 5, 6]. Lower [6] demonstrated at Oxford the bleeding of a dog until its strength was nearly gone, but then revitalized the previously moribund dog by exchange transfusion using blood from two other dogs, resulting in the death of the donor animals.

Subsequently, a controversy developed over who had first done a transfusion. In 1669, Lower contended that he had published the results of transfusion in the Philosophical Transactions of the Royal Society in December 1666. In 1667, Jean Denis of France described his experiments in animals and applied the technique to human, which Lower had accomplished only in animals. Others mentioned as possibly having carried out animal‐to‐animal transfusions about this time are Johann‐Daniel Major of Cologne, Johann‐Sigismund Elsholtz of Berlin, don Robert de Gabets (a monk) in France, Claude Tardy of Paris, and Cassini and Griffone in Italy [1].

Denis apparently was a brilliant young professor of philosophy and mathematics at Montpellier and physician to Louis XIV. In 1667, Denis carried out what is believed to be the first transfusion of animal (lamb’s) blood to a human. A 15‐year‐old boy with a long‐standing fever who had been bled multiple times received about 9 ounces of blood from the carotid artery of a lamb connected to the boy’s arm vein. Following the transfusion, the boy changed from a stuporous condition to a clear and smiling countenance. During the next several months, Denis may have given transfusions to three other individuals [1]. The second patient, Antoine Mauroy, was an active 34‐year‐old who spent some of his time carousing in Paris. It was thought that blood from a gentle calf might dampen Mauroy’s spirits. On December 19, 1667, he received with no untoward effects 5 or 6 ounces of blood from the femoral artery of a calf. Several days later, the procedure was repeated. During the second transfusion, Mauroy experienced pain in the arm receiving the blood, vomiting, increased pulse, a nosebleed, pressure in the chest, and pain over the kidneys; the next day he passed black urine. This is probably the first reported hemolytic transfusion reaction. Mauroy died about 2 months later without further transfusions. Reportedly, members of the Faculty of Medicine who were opposed to transfusion and hated Denis bribed Mauroy’s wife to state that he had died during the transfusion [1]. Denis was tried for manslaughter but was exonerated. It was later revealed that Mauroy’s wife had been poisoning him with arsenic and that was the actual cause of his death [7]. Also in late 1667, Lower performed a human transfusion before the Royal Society in England. The man received 9–10 ounces of blood from the artery of a sheep and was said to have “found himself very well” afterward [1]. However, the death of Mauroy was used by Denis’s enemies as an excuse to issue an edict in 1668 that banned the practice of transfusion unless the approval of the Faculty of Medicine in Paris was obtained. This series of events led to the discontinuation of transfusion experiments, but more importantly to the abandonment of the study of the physiology of circulation for approximately 150 years [1].

Interest in transfusion was revived during the early 1800s, primarily by James Blundell [8], a British obstetrician who believed it would be helpful in treating postpartum hemorrhage. Blundell carried out animal experiments and avoided the error of using animal blood because of the advice of a colleague, Dr. John Leacock. Blundell reported to the Medico‐Chirurgical Society of London on December 22, 1818, the first human‐to‐human transfusion. It is not clear whether the transfusions given by Blundell were ever successful clinically [1]. However, Blundell’s [8] contributions were very substantial. Unfortunately, his warnings about the dangers of transfusing animal blood into humans were not generally heeded.

Dr. Andrei Wolff carried out a human‐to‐human transfusion in St. Petersburgh, Russia, in 1832, having learned of blood transfusion from Dr. Blundell on a previous visit to London [9]. There is no evidence of additional transfusion in Russia until the 1920s, when a transfusion institute was established in Moscow.

Key work in understanding the problems of using animal blood for human transfusions was provided by Ponfick and Landois [1]. They observed residues of lysed erythrocytes in the autopsy serum of a patient who died following transfusion of animal blood. They also noted pulmonary and serosal hemorrhages, enlarged kidneys, congested hemorrhagic livers, and bloody urine caused by hemoglobinuria and not hematuria when sheep’s blood was transfused to dogs, cats, or rabbits. Landois observed that human red cells would lyse when mixed in vitro with the sera of other animals. Thus, evidence mounted that interspecies transfusion was likely to cause severe problems in the recipient.

In the United States, transfusions were first used in the mid‐1800s, but it is not clear where they were first performed. They may have been done in New Orleans in about 1854 [2]. During the Civil War, the major cause of death was hemorrhage [10]. However, at that time blood transfusion had not been developed, and it appears to have been used in only two to four patients [2]. Two cases are described by Kuhns [10]. One was transfused at Louisville and one at Alexandria within about 10 days of each other. There is no evidence that the procedures were jointly planned or that the physicians involved communicated about them. In both cases, the patients improved following the transfusions [10].

The accumulating experiences began to make it clear that transfusions should be performed only between members of the same species. However, even within species, transfusions could sometimes be associated with severe complications. Because of this, and despite the experiences during the Civil War, few transfusions were carried out during the last half of the 1800s. The discovery of blood groups by Landsteiner [11] opened a new wave of transfusion activity. It had been known that the blood of some individuals caused agglutination of the red cells of others, but the significance of this was not appreciated until Landsteiner [11] in 1900 reported his studies of 22 individuals in his laboratory. He showed that the reactions of different combinations of cells and sera formed patterns and these patterns indicated three blood groups [11]. He named these blood groups A, B, and C (which later became group O). Apparently, none of the staff of Landsteiner’s laboratory had the less common group AB, but soon this blood group was reported by the Austrian investigators Decastello and Sturli [1]. Soon thereafter, several other nomenclature systems were proposed, and the American Medical Association convened a committee of experts who recommended a numerical nomenclature system [12] that never gained widespread use [11]. Others later demonstrated that the blood groups were inherited as independent Mendelian dominants, and that the phenotypes were determined by three allelic genes. Hektoen [13] of Chicago first advocated the use of blood grouping to select donors and recipients and to carry out transfusion, but it was Ottenberg [14] who put the theory into practice. These activities are the basis for the widely held belief that blood banking in the United States had its origins in Chicago.

Another factor that inhibited the use of transfusions during the late 1800s was blood clotting. Because of the inability to prevent clotting, most transfusions were given by direct methods. There were many devices for direct donor‐to‐recipient transfusion that incorporated valves, syringes, and tubing to connect the veins of donor and recipient [15].

Although there were many attempts to find a suitable anticoagulant, the following remarks must be prefaced by Greenwalt’s statement that “none of them could have been satisfactory or else the history of blood transfusion would have had a fast course” [1]. Two French chemists, Prévost and Dumas, found a method to defibrinate blood and observed that such blood was effective in animal transfusions [1]. Substances tested for anticoagulation of human blood include ammonium sulfate, sodium phosphate, sodium bicarbonate, ammonium oxalate and arsphenamine, sodium iodide, and sodium sulfate [16, 17]. The delays in developing methods to anticoagulate blood for transfusion are interesting because it was known in the late 1800s that calcium was involved in blood clotting and that blood could be anticoagulated by the addition of oxalic acid. Citrates were used for laboratory experiments by physiologists, and by 1915 several papers had been published describing the use of sodium citrate for anticoagulation for transfusions [1]. It is not clear who first used citrated blood for transfusion [1]. It could have been Lewisohn [18], Hustin, or Weil [19]. In 1955, Lewisohn received the Landsteiner award from the American Association of Blood Banks for his work in the anticoagulation of blood for transfusion.

Major stimuli for developments in blood transfusion have come from wars. During World War I, sodium citrate was the only substance used as an anticoagulant. Early in the war, transfusions were vein to vein, but in 1917, Dr. Oswald Robertson of the U.S. Army Medical Corps devised a blood collection bottle and administration set similar to those used several decades later [1] and transfused several patients, some estimate hundreds of patients, with preserved blood [20].

Between World Wars I and II, there was increasing interest in developing methods to store blood in anticipation of rather than response to need. It has been suggested that the first “bank” where a stock of blood was maintained may have been in Leningrad in 1932 [1, 2]. A blood bank was established in Barcelona in 1936 because of the need for blood during the Spanish Civil War [21]. In the United States, credit for the establishment of the first blood bank for the storage of refrigerated blood for transfusion is usually given to Bernard Fantus at the Cook County Hospital in Chicago [22]. The blood was collected in sodium citrate and so it could be stored for only a few days. In England, blood donations were begun within days of the outbreak of WWII in 1939. The British established a Home Depot for collecting blood and shipped blood to Europe even during the Dunkirk campaign.

Cadavers served as another source of blood during the 1930s and later. Most of this work was done by Yudin [23] in the USSR. Following death, the blood was allowed to clot, but the clots lysed by normally appearing fibrinolytic enzymes, leaving liquid defibrinated blood.

The use of cadaver blood in the Soviet Union received much publicity and was believed by many to be the major source of transfusion blood there. Actually, not many more than 40,000 200‐mL units were used, and most of them at Yudin’s Institute [1]. In 1967, the procedure was quite complicated, involving the use of an operating room, a well‐trained staff, and extensive laboratory studies. This was never a practical or extensive source of blood.

In 1939, Levine, Newark, and Stetson [24] published in less than two pages in the Journal of the American Medical Association their landmark article, a case report describing hemolytic disease of the newborn (HDN) and the discovery of the blood group that later became known as the Rh system. A woman who delivered a stillborn infant received a transfusion of red cells from her husband because of intrapartum and postpartum hemorrhage. Following the transfusion, she had a severe reaction but did not react to subsequent transfusions from other donors. The woman’s serum reacted against her husband’s red cells, but not against the cells of the other donors. Levine, Newark, and Stetson postulated that the mother had become immunized by the fetus, who had inherited a trait from the father that the mother lacked. In a later report, they postulated that the antibody found in the mother and subsequently in many other patients was the same as the antibody Landsteiner and Wiener prepared by immunizing Rhesus monkeys [25]. This also began a long debate over credit for discovery of the Rh system.

During the early 1900s, immunologic studies had established that active immunization could be prevented by the presence of passive antibody. This strategy was applied to the prevention of Rh immunization in the early 1960s in New York and England at about the same time [26, 27]. Subjects were protected from Rh immunization if they were given either Rh‐positive red cells coated with anti‐Rh or anti‐Rh followed by Rh‐positive red cells. Subsequent studies established that administration of anti‐Rh in the form of Rh immune globulin could prevent Rh immunization, and thus almost eliminate HDN. Currently, control of HDN is a public health measure similar to ensuring proper immunization programs for susceptible persons.

In 1908, Moreschi [28] is said to have described the antiglobulin reaction. The potential applicability of this in the detection of human blood groups was not appreciated until 1945, when Coombs, Mourant, and Race [29] published their work on studies of the use of rabbit antibodies against human IgG to detect IgG‐coated red cells. Red cells were incubated with human sera containing antibodies against red cell antigens and washed, and the rabbit anti‐human sera were used to demonstrate the presence of bound IgG by causing agglutination of the red cells. The availability of anti‐human globulin serum made it possible to detect IgG red cell antibodies when the antibody did not cause direct agglutination of the cells. Thus, red cells coated with anti‐IgG red cell antibodies could be easily detected, and the era of antibody screening and crossmatching was born. This greatly improved the safety of blood transfusion and also led to the discovery of many red cell antigens and blood groups.

Techniques for collection, storage, and transfusion of whole blood were not well developed during the 1930s. The outbreak of World War II added further impetus to the development of methods to store blood for periods longer than a few days. Although the method of blood anticoagulation was known by the mid‐1920s, red blood cells hemolyzed after storage in sodium citrate for 1 week. This limitation also slowed the development of blood transfusion. Although it was also known that the hemolysis could be prevented by the addition of dextrose, the practical value of this important observation was not recognized for more than a quarter of a century. Anticoagulant preservative solutions were developed by Mollison [30] in Great Britain. However, when the glucose–citrate mixtures were autoclaved, the glucose caramelized, changing the color of the solution to various shades of brown. The addition of citric acid eliminated this problem and also extended the storage time of blood to 21 days. The advance of World War II also brought an understanding of the value of plasma in patients with shock [31, 32]. In the early 1940s, Edwin J. Cohn, PhD, a Harvard biochemist, developed methods for the continuous flow separation of large volumes of plasma proteins [33, 34]. This made possible during World War II the introduction of liquid and lyophilized plasma and human albumin as the first‐line management of shock. Initial work using plasma for transfusion was carried out by John Elliott [31, 32]. This combination of technological and medical developments made it possible for Charles R. Drew to develop the “Plasma for Britain” program [35].

One of the next major developments in blood banking was the discovery and patenting of the plastic blood container by Carl Walter in 1950. This made possible the separation of whole blood and the creation of blood component therapy. Dr. Walter’s invention was commercialized by the Baxter Corporation. The Fenwal division later became a freestanding company; the “‐wal” of “Fenwal” represents Dr. Walter’s name. The impact of the introduction of multiple connected plastic containers and the separation of whole blood into its components also began to generate enormous amounts of recovered plasma, which made possible the development of large‐scale use of coagulation factor VIII concentrates.

In 1965, Dr. Judith Pool reported that if fresh frozen plasma was allowed to thaw at refrigerator temperatures, precipitate remained that contained most of the coagulation factor VIII from the original fresh frozen plasma [36]. This made it possible for the first time to administer large doses of factor VIII in a concentrated form to patients with hemophilia and opened an era in which the bleeding diathesis could be effectively managed. A few years later, reports began to appear describing the use of a concentrated factor VIII prepared using the plasma fractionation technique developed by Edwin Cohn [33]. This further simplified the management of hemophilia because the ability to store the factor VIII concentrates in home refrigerators enabled the development of home treatment programs involving prophylactic or immediate self‐administration of factor VIII.

The role of 2,3‐diphosphoglycerate in oxygen transport by red cells was discovered in the mid‐1960s [37, 38]. It had been known previously that this compound was better maintained at higher pH, whereas adenosine triphosphate, which appeared to be involved in red cell survival, was maintained better at a lower pH. The addition of adenine was shown to improve adenosine triphosphate maintenance and prolong red cell survival and storage for transfusion [39]. The next major advance in red cell preservation was the development of preservative solutions designed to be added after removal of most of the original anticoagulated plasma, thus further extending the storage period of red cells [40].

In 1926, Doan [41] described the sera of some individuals that caused agglutination of the leukocytes from others. Subsequent studies established the presence of leukocyte antibodies, the presence of these antibodies in the sera of polytransfused patients, the occurrence of white cell agglutinins in response to fetomaternal immunization, and the alloimmune and autoimmune specificities associated with these antibodies. These studies, along with studies of the murine histocompatibility system, led to the description of the major histocompatibility system (human lymphocyte antigens) [42] in humans and the understanding that there are separate antigenic specificities limited to neutrophils as well [43]. These studies also defined the causative role of leukocytes in febrile nonhemolytic transfusion reactions [44]. Strategies were sought to prevent these reactions by removing the leukocytes from blood [45, 46], one of the first methods being reported by Fleming [46], who discovered penicillin.

The relationship between bleeding and thrombocytopenia had been known for some time, but the development of the plastic bag system for blood collection made platelets available for transfusion. Several years of work by many investigators—predominantly at the National Cancer Institute during the 1960s—developed the methods for preparing platelets and established that platelet transfusion to patients with thrombocytopenia reduced mortality from hemorrhage [47]. Initially, platelets had to be transfused within a few hours after the whole blood was collected, and thus large‐scale application in the general medical care setting was impractical. The seminal report by Murphy and Gardner [48] showing that room temperature allowed platelets to be stored for several days revolutionized platelet transfusion therapy.

Plastic bags were used to remove whole blood, separate the plasma from the red cells, retain the plasma, and return the red cells, thus making it possible to obtain substantial amounts of plasma from one donor [49]. This initiated the concept of attempting to obtain only selected portions of whole blood to collect larger amounts of plasma or cells. The centrifuge developed by Cohn for plasma fractionation was modified by Jack Latham and became a semiautomated system for plasmapheresis [50] and subsequently was used for platelet collection as well [51, 52]. At the National Institutes of Health Clinical Center, an IBM engineer worked with hematologists to develop a centrifuge that enabled collection of platelets or granulocytes from a continuous flow of blood through the instrument [53, 54]. Later versions of these instruments have become widely used for plateletpheresis and leukophoresis.

As the benefits of platelet transfusion for thrombocytopenic patients were recognized, interest developed in using the same strategy to provide granulocyte transfusion to treat infection in patients with neutropenia. Initial attempts involved obtaining granulocytes from patients with chronic myelogenous leukemia [55, 56]. Transfusion of these cells had clinical benefits [57], and this led to a decade of effort to develop methods to obtain granulocytes from normal donors [58]. At best, these methods produced only modest doses of granulocytes; improvements in antibiotics and general patient care have supplanted the need for granulocyte transfusions except in very limited circumstances (see Chapters 10 and 11).

Blood banking and transfusion medicine developed slowly during the 1950s but much more rapidly between the 1960s and the 1980s. Some of the important advances mentioned in this chapter were understanding blood groups and the identification of hundreds of specific red cell antigens; the development of the plastic bag system for blood collection and separation; plasma fractionation for the production of blood derivatives, especially factor VIII; improved red cell preservation; platelet preservation and transfusion; understanding hemolytic and febrile transfusion reactions; expanded testing for transmissible diseases; and the recognition of leukocyte and platelet antigen systems. Blood collection and storage is now a complex process operated much like the manufacturing of a pharmaceutical. Transfusion medicine is now the complex, sophisticated medical–technical discipline that makes possible many modern medical therapies.

Jeffrey McCullough MD

Blood transfusion occurs in all parts of the world, but the availability, quality, and safety of the blood depends on the general status of medical care in that area. Approximately 1,215,000 units of blood are collected annually worldwide [1]. The amount of blood collected in relation to the population ranges from 50 donations per 1,000 population in industrialized countries to 0.3 donation per 1,000 in the least developed countries [1]. Thus, there is a concentration of blood transfusions in industrialized countries, with 15% of the world’s population receiving approximately 48% of the world blood supply [1]. Lack of blood is a major problem in many parts of the world.

Blood services are best provided if there is a national, or at least regional, organization [2]. It is important that the government makes a commitment to the nation’s blood supply (Table 2.1). Blood may be collected by individual hospitals, private blood banks, the Red Cross, Ministries of Health, or some other part of the national government. The number of units of blood collected at individual centers can range from a few hundred to thousands per year, and there may be extensive or little coordination and standardization. The adoption of a national blood policy is recommended, along with establishing a national organization [2]. This has been achieved in the developed world, where virtually all countries operate a national blood supply system as part of their public health structure as recommended by the World Health Organization (WHO) [2–5], and is beginning in other parts of the world [6–13]. The United States is essentially the only developed country without a single unified national blood supply organization.

Table 2.1 Key elements of a nationally coordinated blood transfusion service.

Blood transfusion safety: voluntary blood donation, national blood transfusion services, and safe and appropriate use; World Health Organization website programs and projects.

Although great progress has been made in establishing national or centralized blood transfusion services, some blood is still collected without national control or organization. In many parts of the world, there is little or no organized donor recruitment system and so the blood supply fluctuates. Donors may be friends or relatives of patients, voluntary nonremunerated volunteers (VNRDs), or paid donors. Although the WHO urges the use of VNRD, this source is inadequate in many countries, and VNRD rates range from 0% to 100%, with a median of 45% [1]. In low‐resource countries, more than almost half of blood is donated by friends or relatives of patients who are transfusion recipients (Table 2.2) [13–16]. Although these donors are considered to be volunteers, they may be donating under family pressure or they may be individuals unknown to the family who have been paid to donate blood. This is unfortunate because the risk for transfusion‐transmitted infection from first‐time [2, 15, 17] and paid donors is much higher than from volunteers [18] (see Chapter 3). These risks are further accentuated by the lack of comprehensive testing of donor blood for transfusion‐transmissible diseases that sometimes occurs in developing and least developed countries (Table 2.2). In many countries, blood donations are not tested routinely for the combination of human immunodeficiency virus (HIV), hepatitis B virus (HBV), hepatitis C virus, and syphilis [1]. This is because of a shortage of trained staff, unavailability of or poor quality of test kits, or infrastructure breakdowns. Sometimes transmissible disease testing is not done because the need is so urgent that the blood must be transfused immediately after it is collected. Rapid tests may be useful [19]. The cost of transmissible disease testing is also problematic because it may approach the annual per capita expenditure for all of health care in some countries [20, 21]. This, combined with the use of replacement or paid donors and the low rates of repeat blood donors with their lower rate of positive tests for transfusion‐transmissible diseases, leads to a major concern about blood safety in developing and least developed countries [21, 22]. Impressive progress has been made in establishing testing systems, increasing blood collections, standardizing operations, and increasing the availability of safe blood [3, 5, 7–12]. “Many factors influence the global implementation of self‐sufficiency” [23, 24], and a consensus statement from WHO experts is available defining the rationale [24].

In much of the world, components are not used routinely. The whole blood is converted into components ranging from <25% in low‐resource countries to 97% in high‐income countries, and use of whole blood ranges from 0% to 100% [1].

In contrast with the worldwide supply, the US blood supply is provided by many different organizations with different organizational structures and philosophies. These organizations function rather effectively to meet the nation’s blood needs, and thus are referred to in this chapter as the US blood supply system, although they are not really a unified system.

Table 2.2 Activities related to blood availability and safety in different countries.

Source: Data are summarized from Gibbs WN, Corcoran P. Blood safety in developing countries. Vox Sang 1994; 67:377–381.

HBC, hepatitis B virus; HIV, human immunodeficiency virus.

The US blood collection system is heterogeneous because blood centers developed for a variety of reasons mostly during the 1940s and 1950s. Some were continuations of blood collection activities initiated during World War II; others were civic or philanthropic activities, and some were formed by groups of hospitals to collect blood for their own needs. However, most hospitals have stopped collecting blood; therefore, currently about 90% of the US blood supply is collected by blood centers [25, 26].

Traditionally, blood centers were freestanding organizations, almost all of which were nonprofit. These centers were governed by a board of local volunteers; their sole or major function is to provide the community’s blood supply. Each blood center collects blood in a reasonably contiguous area. The blood center may supply hospitals in its area but may supply hospitals in other areas as well. The area covered by each center was determined by historical factors and was not developed according to any overall plan. Rather, local interests dictated whether, how, and what kind of community blood program was developed. There is a total of approximately 66 accredited blood centers in the United States [25, 26], although these are combining and it appears that soon there may be only a few blood collection organizations in the United States. As a result of the HIV epidemic [27], the regulatory environment changed [28], and the blood collection system in the United States underwent substantial revisions [26–28]. The organizations have adopted philosophies and organizational structures resembling those found in the pharmaceutical industry rather than the previous hospital laboratory and medical model. Modern quality assurance systems and good manufacturing practices [28, 29] like those used in the pharmaceutical industry have been introduced. New computer systems now provide greater control over the manufacturing process [29], and changed management structures deal with the new kinds of activities and philosophy. Blood centers and supply organizations are now operated using a very structured business and manufacturing philosophy, organization, and culture (see Chapter 21). This structure is now undergoing extensive change. Blood centers are merging, forming large national organizations that have less local focus. These organizations collect blood in the most efficient manner and sell that blood where it is more advantageous.

Most hospitals in the United States do not collect any blood but rather acquire all of the blood they use from a community center. Blood banks that are part of hospitals usually collect blood only for use in that hospital and do not supply other hospitals. However, few, if any, hospitals collect enough blood to meet all of their needs. They purchase some blood from a local or distant community blood center. Of those that do collect blood, there are no good data available to define the proportion of their needs that they collect. This can be presumed to be quite variable and involve primarily plateletpheresis.

Periodically the CDC surveys blood collection organizations and hospitals to determine the blood supply and utilization [26]. The most recent report is from 2017, when data were obtained from 88% of blood suppliers and 80% of hospitals. In 2017, 10,397,000 units of allogeneic whole blood and 10,000 units of autologous blood were collected [26]. An additional 1,794,000 units of red cells (15%) was collected by apheresis, giving a total of 12,201,000 units. Laboratory testing led to discard of 78,000 (0.6%), and an additional 590,000 units was not suitable for use, leaving a total of 11,533,000 units available for transfusion [26].

There have been several trends in the nation’s blood supply since the 1970s, partly influenced by the AIDS epidemic. From 1980 to 1988, there was an increase in the amount of allogeneic blood collected [25] (Figure 2.1). Between 1988 and 1998, there was a substantial increase followed by an increase and then plateau from 1997 to 2008. However, a substantial decrease has occurred since then, with a 3% decrease from 2015 to 2017 [26]. The decrease in collections reflects a decreased use of 6.8% from 2015 to 2017 [26]. Autologous donations showed a surprising increase of 35%, although the number of units was very small (27,000) [26]. Collection of red cells by apheresis was essentially unchanged from 2015, but this represents a valuable portion of the red cell supply of about 15% in 2017 and is particularly helpful in collecting blood from type O donors [26]. Almost all blood is converted into components; however, in 2017, 5,776 units of whole blood were distributed [26]. Of whole blood and red blood cells collected, 5% were not used.

In the United States, most platelets are produced by plateletpheresis, although a few are prepared from whole blood. In 2017, 2.259,000 units of platelets were provided. The number of plateletpheresis procedures was smaller because a median of 1.9 products were obtained from most procedures [26]. This is a 4.6% increase from 2015. Most (93.4%) platelets are prepared and stored in plasma and the remainder in platelet additive solutions [26]. Although most platelets are prepared by plateletpheresis, 221,000 units, or 9% of the supply were prepared, from whole blood (see Chapter 5). Apheresis platelets are used primarily, but as many as 19% were not used in 2017 [26].

Most plasma for transfusion is a by‐product of whole blood. Depending on how it is prepared, this may become fresh frozen plasma, plasma frozen within 24 hours, or cryoprecipitate‐reduced plasma (see Chapter 5). In 2017, 3,210,000 units of all plasma products were produced, and 2,318,000 (72%) were used [26]. This represents a 13.6% decrease in products and a 15% decrease in use. Cryoprecipitate production increased 16% to 2,156,000 units, but use decreased 8.5% to 1,068,000 from 2015.

Certain areas of the United States are chronically unable to collect enough blood to meet their local transfusion needs. This occurs mostly in metropolitan areas that serve large trauma, tertiary, and transplantation centers. This can cause several difficulties, including possible unavailability of blood or components when needed, complex inventory management, technical disparities, emergency appeal‐type donor recruitment, higher costs, decreased independence, and higher‐risk management costs. As the nature of blood supply organizations has changed (see earlier US Blood Supply section), local and regional relationships have weakened, and each organization manages to collect and distribute their products in the most cost‐efficient and revenue‐generating way possible.

This process of moving blood considerable distances is increasing as hospitals contract with blood suppliers based on cost and availability, breaking long‐time regional or local relationships. This has converted most blood supply organizations into a national perspective.

Despite the fact that there is not a unified blood banking system or a single national inventory or blood resource–sharing system in the United States, blood suppliers have made major efforts to use blood from areas where it is available in excess. Since 1953, the American Association of Blood Banks (AABB) has operated the National Blood Exchange that coordinates the distribution of many units of blood and components annually. These blood‐sharing systems have become less important as the supply organizations have consolidated and become part of larger organizations that manage their own inventory on a national basis.

One of the major issues in blood inventory management is the attitude of blood donors. In the only study focused on donors’ attitudes about being asked to donate more blood than is needed by their local community [31], donors to several American Red Cross blood centers indicated a willingness to donate for patients in other areas of the United States as long as their local blood needs were being met.

In the past, blood centers carried out a variety of activities that provided services in addition to the blood components. These included continuing education for physicians, technologists, and/or nurses; human leukocyte antigen typing; therapeutic apheresis; red cell reference laboratory testing; outpatient transfusions; and medical consultation for transfusion medicine. These services were often provided to hospitals and the medical technical nursing community at little or no extra charge because the activities were subsidized by the income generated from the charges for the blood components. However, as blood centers have attempted to stabilize or reduce their prices to hospitals, it has become necessary for these additional services to become self‐supporting financially. In most situations, hospitals have been unwilling to pay for the services; as a result, blood centers have reduced or eliminated these activities. Blood centers are now more narrowly focused on collecting and distributing blood.

A method was developed at the beginning of World War II to process large volumes of plasma so that some of the proteins could be isolated, concentrated, and used for medical purposes [32]. This plasma “fractionation” process is the basis for a large industry that provides many medically valuable products generally referred to as plasma “derivatives” [33–35]. The plasma for production of these derivatives is obtained by plasmapheresis. Members of the Plasma Protein Therapeutics Association (PPTA) carry out approximately 44 million plasmapheresis procedures annually and collected about 44 million liters of plasma [35]. There are many US Food and Drug Administration (FDA)–licensable plasma derivatives (see Chapter 5). The production of these plasma derivatives is a complex manufacturing process that takes 7–9 months and usually involves batches up to 10,000 L of plasma or plasma from as many as 50,000 donors (see Plasma Protein Therapeutics Association section later in this chapter).

The FDA uses two terms for plasma that may serve as the starting material for the manufacture of derivatives: plasma and source plasma. Plasma is “the fluid portion of one unit of human blood intended for intravenous use” [36]. This plasma, which is a by‐product of whole blood collected by blood supply organizations or hospitals, is sold to commercial companies in the plasma fractionation industry, who in turn manufacture the plasma derivatives and sell them in the pharmaceutical market. The blood banks’ sale of their plasma to the commercial fractionator (manufacturer) may, but usually does not, involve an agreement to provide some of the manufactured derivatives back to the blood bank.

The amount of plasma obtained from whole blood is not adequate to meet the needs for raw material to produce plasma derivatives. Although plasma collection data are not readily available, an estimated 44 million liters is probably collected annually by plasmapheresis in about 650 collection centers in North America [35]. This is called source plasma, which is “the fluid portion of human blood collected by plasmapheresis and intended as the source material for further manufacturing use” [36]. Automated instruments are usually used to obtain 650–1000 mL of plasma up to twice weekly from healthy adult donors. An individual can donate up to about 100 L of plasma annually in the United States, if the plasma protein levels and other laboratory tests and physical findings remain normal.

Organizations and facilities need FDA licenses for either plasma collection or the manufacture of derivatives from plasma, or both, depending on the activities they conduct. In the past decade, this system has undergone considerable consolidation.

Countries other than the United States have nonremunerated plasma donor programs; however, few, if any, of these provide all of the plasma needs. The US system of paid plasma donors produces about 80% of the US and 60% of the world’s plasma supply [35]. Thus, the United States is a major exporter of plasma or finished product derivatives.

Data regarding the plasma derivative industry is proprietary and thus is not readily available. It is estimated that the US plasma and plasma products industry employs more than 10,000 people nationwide and may produce 44 million liters or more of plasma annually in the United States. Individuals who donate plasma to support the plasma derivative industry receive $20 or more per donation, and it is estimated that donors receive compensation of millions from plasma collection facilities annually. This is in contrast with whole blood donors, who donate voluntarily and do not receive compensation. Much of the plasma obtained from whole blood collected by blood banks is also used for derivative production. The volume of this plasma can be very roughly estimated as follows: approximately 12 million units of whole blood, suitable for use, is collected annually. If approximately 5 million units is used for frozen plasma and cryoprecipitate, the remaining 7 million units could produce about 1.5 million liters of plasma, which is not nearly enough to meet the need for the manufacture of derivatives.

Some organizations such as the American Medical Association, the College of American Pathologists (CAP), the American College of Surgeons, or the American Society of Anesthesiologists, may from time to time take positions on blood bank– and transfusion medicine–related issues, and maintain blood bank or transfusion medicine committees. The American Society of Hematology includes transfusion medicine in its scientific programs and a section of its journal Blood. Several nongovernmental or professional organizations are devoted exclusively to blood banking and transfusion medicine.

The AABB is a professional, nonprofit, scientific, and administrative association for individuals and institutions engaged in the many facets of blood transfusion and cellular therapies. AABB member facilities collect virtually all of the nation’s blood supply and transfuse more than 80% to recipients. Approximately 900 institutions (community, regional, and American Red Cross blood centers; hospital blood banks; and hospital transfusion services) and approximately 5,500 individuals are members of the AABB. Members include physicians, scientists, medical technologists, administrators, blood donor recruiters, nurses, and public‐spirited citizens. The services and programs of the AABB include inspection and accreditation, standard setting, certification of reference laboratories, operation of a rare donor file, establishment of group purchasing programs, operation of a liability insurance program for blood banks, certification of specialists (technologists) in blood banking, collection of data about the activities of the membership, conduct of regional and teleconference educational programs, provision of professional self‐assessment examinations, and conduct of donor recruitment and public education seminars. In addition, the AABB sponsors the world’s largest annual meeting, where results of new research in blood banking and transfusion medicine are presented; publishes Transfusion, the nation’s leading journal reporting scientific, technical, and medical advances in blood banking and transfusion medicine; provides legislative and regulatory assistance to members; develops a wide variety of educational materials for blood bank professionals; and supports the National Blood Foundation, which provides funds for research in transfusion medicine and blood banking.

Institutional members of the AABB are classified either as a blood center, a hospital blood bank, or a hospital transfusion service. The blood center collects blood and distributes it to several hospitals but does not transfuse blood. A hospital blood bank both collects and transfuses blood, and a hospital transfusion service transfuses but does not collect blood.

America’s Blood Centers (ABC) is an association of independent (that is, not American Red Cross) not‐for‐profit community blood centers established in 1962. Efforts to meet the goals of safety, quality, and efficiency in blood services are met through programs such as group purchasing of supplies, services, and liability insurance; efforts to increase volunteer blood donation; effective sharing of blood resources; strengthening of blood center management skills; training programs to ensure compliance with federal regulations; and efforts to ensure fair and balanced resolution of disputes between blood centers and the public they serve. ABC works nationally by helping to shape and influence federal and state regulations, policies, and standards of care that its membership believes are in the best interest of the donors and patients they serve. The association also works to identify and promote needed research and development in blood services; promotes information exchange between members of operational practices; and promotes new programs, policies, and ideas by conducting surveys and meetings of small working groups and by developing workable models. ABC has approximately 70 institutional members with about 600 donor centers throughout the United States that collect about 60% of the nation’s volunteer donor blood supply.

The PPTA is a trade association that advocates for the world’s source plasma collectors and producers of plasma‐based therapeutics [35]. Members of PPTA represent nearly every company in the world that collects source plasma for further manufacture. These members operate about 650 plasma collection facilities worldwide and carried about 38 million donations in the United States in 2018 [37]. The role of PPTA is to develop standards and training programs, represent the industry to the public and governments, and provide forums for discussion of new issues or technology.

The WHO operates a program in Blood Safety and Clinical Technology [1–3]. The program involves developing guidelines for nationally coordinated blood programs, national blood policies, technical support, a Global Collaboration for Blood Safety program, country‐level activities to improve access to safe blood, a Quality Management Project, Guidelines on the Clinical Use of Blood, maintaining the chain of reagents and materials needed for blood operation, laboratory personnel safety, and the safe use of injectables and injection materials. It also sponsors a wide variety of educational symposia worldwide.

The Federation of Red Cross and Red Crescent Societies, located in Geneva, Switzerland, is the central coordinating organization for all individual country Red Cross or Red Crescent Societies. Although most of the Federation’s activities involve humanitarian assistance in times of war or disaster, there is a small blood program office. Approximately 180 National Red Cross or Red Crescent Societies are involved in blood programs. Because of the wide variety of Red Cross involvement and the diverse nature of these Red Cross blood programs, the focus of the blood program at the Federation is on blood donor recruitment. When appropriate, the Federation collaborates with the Global Blood Safety unit at WHO, which is made all the more convenient by their close proximity.

The International Society for Blood Transfusion, founded in 1935, is composed of almost 1,400 medical, scientific, technical, or managerial individuals involved with blood transfusion. Members represent more than 100 countries. The mission of the International Society for Blood Transfusion is to establish close and mutually beneficial working relationships with international and national professional societies, together with intergovernmental and nongovernmental organizations. By this means, it is possible to disseminate knowledge of how blood transfusion medicine and science may best serve the patient; to create global and regional opportunities for the presentation of research, new developments, and changing concepts in blood transfusion medicine and science and related disciplines; to make provision for the exchange of views and information among members; to promote and to maintain a high level of ethical, medical, and scientific standards in blood transfusion medicine and science throughout the world; and to encourage the development of collaborative programs of good manufacturing and laboratory and user practices in all countries, particularly those with less well‐developed blood transfusion services. The Society publishes Vox Sanguinis, a scientific journal on blood transfusion, transfusion medicine, and blood banking, and a newsletter, Transfusion Today. It also sponsors world and regional congresses, which provide an excellent forum for discussion of not only highly technical subjects and innovations but also issues important to less developed blood transfusion situations.

Blood is considered a drug and is regulated by the FDA. The legal basis for this regulation of blood, blood components, and plasma derivatives is provided by two separate but overlapping statutes, one governing “biologics” and one governing “drugs.” The biologics law requires that any “virus, therapeutic serum, toxin, anti‐toxin, or analogous product” be prepared in a facility holding an FDA license [36]. A separate law, the Pure Food and Drugs Act, covers drugs intended for the “cure, mitigation, or prevention of disease,” and thus includes biologics such as blood and blood components or plasma derivatives. Thus, blood banks are subject to the biologics and the drug regulatory process. The federal requirements for blood banks are specified in the Code of Federal Regulations. In addition, the FDA publishes “guidelines” that specify the agency’s recommendations of specific policies, procedures, or actions regarding any aspect of the acquisition of blood.

FDA law requires that all organizations involved in “collection, preparation, processing, or compatibility testing … of any blood product” [36] register with the FDA. This registration allows the organization to collect blood and prepare blood components for its own use. If the organization wishes to ship the components across state lines or engage in commerce by selling the products to other organizations, the organization must obtain an FDA license for this purpose. Thus, for practical purposes, most hospitals that collect blood or prepare blood components for their own use are registered, but not licensed, because they do not ship blood in interstate commerce. Most blood centers are licensed, because they supply multiple hospitals, some of which may be in other states. In addition, blood centers may wish to participate in blood resource sharing with blood centers in other states, and thus need to be licensed for interstate shipment of blood.

Federal licensure is intended to ensure that the facility in which the biologic is produced will provide products with high purity and quality. In addition to licensing the facility or establishment, this law requires that each biologic product itself be licensed by the FDA. Thus, to produce a licensed biologic, an organization must have an establishment license describing the facility in which the product is produced and a product license describing the specific product being produced. Over the years, this law has been specifically amended to include the terms blood and blood component or derivative to make it clear that blood is subject to the biologics’ regulation. Blood banks and plasma derivative manufacturers are inspected every other year by the FDA, and they must submit a report annually to the FDA indicating which products are collected, tested, prepared, and distributed.

When an organization applies for an FDA license to produce blood components or plasma derivatives, it must provide the credentials of the person in charge (responsible head) and of those responsible for determining donor suitability, blood collection, and laboratory processing and testing. In addition, it must provide blueprints and floor plans of the facility; descriptions of all equipment; indications of any other activities occurring in the facility; provisions for housekeeping, pest control, ventilation, lighting, and water systems; other occupants of the building; activity in adjacent buildings; record maintenance systems; validation of all systems; quality‐control/assurance programs; procedures for receipt and handling of raw materials; source of starting materials; methods and facilities for any chemical purification; inactivation or transfer steps; formulation and final product preparation; computer systems; and other miscellaneous information.

Along with the establishment license, the organization must file a product license application for each product it plans to produce in the facility. For whole blood and components, the product application involves basic information about the manufacturer (organization), facility, product, standard operating procedures, blood donor screening tests, frequency of donation, donor medical history, presence of a physician, phlebotomy supplies, venipuncture technique, collection technique, allowable storage period, storage conditions, disposal of contaminated units, supplies and reagents, label control processes, procedures for reissue of blood, and a brief summary of experience testing 500 samples. For the manufacture of plasma derivatives, the product license application involves the manufacturer’s (organization’s) name; the establishment name; procedures for determining donor suitability, including medical history, examination by physician, laboratory testing, and methods of preparing the venipuncture site and collecting the plasma; methods to prevent circulatory embolism and to ensure return of red cells to the proper donor; minimum intervals between donation and maximum frequency of donation; techniques for immunizing donors; laboratory tests of collected plasma; techniques of preparing source plasma and storing it; methods to ensure proper storage conditions and identification of units; and label control systems and shipping conditions and procedures.

Blood banks are subject to a number of requirements or licensure systems in addition to the FDA. The Clinical Laboratories Improvement Act (CLIA) of 1988 established a new section of the Public Health Service Act that requires the Department of Health and Human Services (HHS) to establish certification requirements for any laboratory that performs tests on human specimens and to certify that those laboratories meet the requirements established by the HHS. Laboratories participating in the Medicare and Medicaid programs or engaged in testing in interstate commerce must comply with these CLIA requirements. The law makes it possible for HHS to approve certain accreditation bodies and state licensure bodies. Because blood banks carry out testing on human material that is in interstate commerce, and because they provide services to Medicare and Medicaid patients, they must comply with CLIA. Several states also require that blood banks have a license to operate or provide blood in that state. These licenses usually involve a specific application and inspection.

The AABB operates a voluntary accreditation system. This Inspection and Accreditation (I&A) program, initiated in 1958, involves a biannual inspection by AABB volunteers. The major intent of the I&A program is to increase the safety in obtaining and transfusing human blood and components. The program is also designed to assist directors of blood banks and transfusion services to determine that knowledge, equipment, and the physical plant meet established requirements; to detect deficiencies in practice; and to provide consultation for their correction. The I&A program can be used to eliminate duplicate inspections by state governments. Many states accept AABB inspection of blood banks and transfusion services to satisfy their licensing requirements. The US Armed Services and Humana, Inc., also maintain an equivalency program with the AABB. The AABB has established a coordinated inspection program with the CAP in which the CAP and AABB inspections are usually done simultaneously.

The CAP, through its Hospital Laboratory Accreditation Program (HLAP), also certifies hospital blood banks, but not community blood centers. The HLAP was initiated in 1961 with the primary objective of improving the quality of clinical laboratory services throughout the United States. The HLAP has grown considerably in size, complexity, and effectiveness since its inception, but the primary goal remains that of laboratory improvement through voluntary participation, professional peer review, education, and compliance with established performance standards. The CAP accredits approximately 4,300 laboratories throughout the United States, as well as several foreign countries.

The HLAP examines all aspects of quality control and quality assurance in the laboratory, including test methodologies, reagents, control media, equipment, specimen handling, procedure manuals, test reporting, and internal and external proficiency testing and monitoring, as well as personnel safety and overall management practices that distinguish a quality laboratory.

Thomas Watkins DO, PhD

The recruitment of donors has undergone several changes over the last few years. Regulatory agencies have allowed for a 1‐year deferral for males having sex with males (MSM), and societal acceptance toward nonbinary/gender fluid donors has had an effect on who presents to donate blood. Further research has raised awareness of iron depletion among donors, and emerging viral and parasitic infections have affected some travel deferrals and are likely to continue to evolve. As traditional print/radio/television media outlets are becoming somewhat less effective in reaching a more diverse donor population, blood providers have needed to become more adept at social media and targeted messaging to different groups. Patient blood management programs and aggressive cost control in hospital supply chain management have increased overall focus on cost savings, driving the process of donor recruitment toward maximum operational efficiency at blood centers from small to large. Health care reform has led hospitals to increasing their focus on cost savings, which has led to blood providers experiencing significant cost constraints. The commoditization of blood and decreasing contract prices for blood products have negatively affected operating margins for many blood centers. Blood collectors are having to do more specific recruiting with less financial resources. In the effort to decrease costs, there have been significant collaborations and mergers between formerly independent blood centers affecting the local identity and community relationships between blood collections and the donor base.

Although most Americans will require a blood transfusion at some time in their lives, it is said that less than 5% of the total population or less than 10% of those eligible to donate have ever done so, although there are no data to directly support this. A surprisingly limited portion of the US population is eligible [1–3]. Many donors give once or infrequently, and much of the nation’s blood supply comes from a small number of dedicated and frequent donors. Blood donors differ from the general population. The demographic characteristics or other factors related to the likelihood of an individual being a blood donor are age, marital status, gender, educational experience, occupation, peer pressure, humanitarianism, fear of the unknown, apathy, self‐esteem, race, social pressure, altruism, volunteerism, convenience, and community service [4–10]. These characteristics are described in more detail in the following subsections.

There is a preponderance of females among first‐time donors [4], but with subsequent donations the ratio shifts to a male preponderance of 60–80% [6, 9], with an overall average of 52% of donors being males [11]. Deferral has a more pronounced effect on first‐time compared with repeat blood donors, and because women are more likely to have a reaction during donation and reactions reduce the likelihood of a donor returning, the gender distribution shifts with advancing age to an increasing percentage of men compared with women. The greatest loss of female donors apparently occurs at about the fourth to eighth donation. In general, the larger the number of lifetime donations the greater is the male preponderance [9]. It seems likely that the shift from female to male donors with increasing numbers of donations is a result of deferral of women in the childbearing age who become iron deficient from menstrual blood loss.

As demographics have changed, there has been an increase in nonbinary gender donors, leading to changes in screening. Further complicating the process are programs of preexposure prophylaxis medication for individuals at risk for acquiring HIV.

Most donors are 30–50 years old, with an average age between 33 and 38 years [4, 9, 11]. The age range of donors shifted during the 1980s and 1990s from only about 2–3% of donors older than 60 years in the 1970s to 10% of donors older than 60 years and 4% older than 65 years in the 1990s [9]. This apparent “aging” of the donor population could reflect a shift in the population age in general; however, during the past few years, blood bank professionals have recognized that blood donation is safe for older individuals, and donor age limits have therefore been extended to attract older donors (see Chapter 4). During the past few years, recruitment of college and high school students has been emphasized, and they now account for about 8% of donations [12]. Younger donors are more likely than repeat donors to experience a reaction [12, 13]. Because donors who experience a reaction are less likely to return [12–15], strategies to minimize reactions in young and first‐time donors are being developed (see Chapter 4). Donors most likely to return are those aged 16 and 17 years and older than 50 years, males, blood group O donors (probably because they are sought by the blood centers), and those without any initial adverse reaction [15, 16].

There are differences in the rate of donation by different ethnic groups. In 1975, whites were 48% more likely to have donated blood during the previous year than non‐whites [17]. By 1989, this figure had increased to 56%. Minority and Latin America–born donors are younger and more likely first time compared with white US‐born donors, but the annual donation frequency of these minority donors is only slightly lower than white US‐born donors [17].

Blood donors tend to have more education and higher incomes than the general population, with incomes as much as 30% higher than those of nondonors. Donors with some college education are the most overrepresented group compared with nondonors. Lightman [18] found that 60% of blood donors in Toronto, Canada, had some post–high school education, compared with 20% for the entire city. Bowman et al. [11] found that 77% of their donors had some post–high school education, with a range of 60–80% in the different blood centers participating in the study. In a separate study, 69% of all donors and 79% of multigallon donors had more than a high school education.

In Bowman et al.’s study [11], 80% of donors were employed full time and another 9% part time. Seven percent were retired, which is consistent with the 10% of donors who were 60 years or older.

It is important to understand donors’ behavior that might increase their likelihood of transmitting disease. Compared with the general population, it appears that donors have fewer sex partners, less frequent sexual experiences, fewer homosexual experiences in males, and are less likely to engage in behavior that puts them at risk for transfusion‐transmissible diseases, although about 1.5% report some kind of risk behavior [19]. In one study, 8% of young “potential” donors tested positive for drugs of abuse [20], but because these were not actual donors, it is not clear whether this experience would apply to blood donors.

As the prevalence of tattooing and other body modifications has increased, a study in the Netherlands by Prinsze et al. [21] reviewed the risks of transfusion‐transmitted infection after tattooing and other needle‐related events. These donors (if deferred) often show low return rates to donation. The authors also demonstrated that donors who reported a tattoo, body piercing, or acupuncture showed no higher risks for transfusion‐transmitted infections [21].

Piliavin and Callero [4] discuss five psychosocial theories that might apply to blood donor motivation: (a) Becker’s model of commitment, (b) the opponent process theory, (c) the attribution/self‐perception framework, (d) the identity theory, and (e) the theory of reasoned action. These can be described briefly as summarized from Piliavin and Callero [4].

In Becker’s theory of commitment, the action or decision is based on background factors or preconceptions. These factors influence whether the person takes the initial action and then the person is subsequently influenced by the first few experiences. In the opponent process theory, the stronger the negative feelings before the action, the stronger are the positive feelings after successfully completing the action. Thus, despite initial fears or negative feelings, a good experience with donation could lead to a strongly positive attitude about continued donation. This theory attempts to account for the continuation of activities that were initially associated with negative feelings. The attribution theory postulates that if an individual believes that there is an external reason for the action, the action is attributed to that external force. In the identity theory, the sense of self is developed from the variety of social roles in which the individual engages. In the theory of reasoned action, the critical factor leading to an act is the development of an intention to carry out the act.

Piliavin and Callero [4] believe that all five of the theories outlined earlier have some relevance to blood donation. The identity theory is thought to be “overarching,” and that the “sense of self as donor is clearly the central factor among the personal determinants of donation” [4]. Becker’s model applies to making the commitment to donate, the opponent process and attribution theories relate to the development of a sense of the individual as a blood donor, and the theory of reasoned action is involved in translating the person’s idea of himself or herself as a blood donor into action to donate. In integrating these theories, Piliavin and Callero [4] believe that the decision to donate is based on “childhood experience factors” negatively influenced by “pain and inconvenience” and positively influenced by “social pressures.”

Experienced donors increasingly internalize the expectations and the role of being a blood donor. Donor identity correlates with the donation intention. Self‐determination theory indicates that people persist with behaviors that are internally versus externally motivated. This theory of self‐determination has been at the basis of thinking about blood donor recruitment [22].

This model is based on attitude, subjective norm, and perceived behavioral control [23]. These influence the intention to carry out behaviors. Although this model has a different name than those of Piliavin and Callero [4], theory of planned behavior really involves attitudes about the behavior, social pressure about the behavior, and control over performing the behavior. Thus, it is not surprising that several studies (reviewed by Masser et al. [23]) indicate that theory of planned behavior predicts a substantial portion of blood donation intention and behavior [24].

The reasons for donating are summarized generally [4] as: (a) extrinsic rewards and incentives, (b) intrinsic rewards and incentives, (c) perceived community needs, (d) perceived community support, (e) social pressure, and (f) addiction to donation. The reasons for not donating include: (a) medical ineligibility, (b) fear, (c) reactions and deferral (poor experiences), and (d) inconvenience and time requirements. Oswalt [6], in reviewing 60 English‐language reports regarding motivation for blood donation, concluded that the following factors were motivations to donate: (a) altruism and humanitarianism, (b) personal or family credit, (c) social pressure, (d) replacement, and (e) reward. Reasons for not donating included: (a) fear, (b) medical excuses, (c) reactions, (d) apathy, and (e) inconvenience. Rados [24] also found that fear, inconvenience, and never being asked were the most common reasons given for not donating. In general, the issues described earlier have seemed to appear rather consistently in these and other studies [25] of donor motivation or nondonation. Because they have been consistent over time, most recruitment strategies attempt to take these factors into consideration. Most blood donors have a rationale way of thinking about blood donation, but some think and make decisions about blood donation based on emotional, personal, or stereotype manner in continuing to donate blood, and the convenience of donation is a stronger factor than helping others [26]. In general, donors give blood out of altruism and in response to a general appeal or a specific request.

About 28% of blood is collected from first‐time donors, about half of whom return within the first year [27]. Those who return tend to be white, US born, and college educated [28]. Experience with the first donation has a major effect on their willingness to return for subsequent donations [4, 14, 16]. Although the first blood donation is anxiety producing, it is usually accompanied by good interactions with the donor staff and good feelings about the donation and oneself [28]. Thus, most donors realize that they are reasonably able to give and plan to do so again. With continued donation, the experience becomes easier and the reasons for continuing to donate become more “internal” [3]. Ferguson et al. [29] propose that the “warm glow” associated with donating supports a general benevolence hypothesis.

About 70–80% of donors are repeat donors, although this percentage is decreasing [16, 30]. Repeat donors tend to be 16 and 17 years or older than 50 years, male, Rh negative, type O, without a reaction during donation, and have a college degree [16, 31]. A shorter interval between the first two donations also predicts more continued donations [28]. Over time a “blood donor role” develops in repeat donors, and this strengthens self‐commitment to blood donation, including “friendships contingent on donating, a self‐description as a regular donor, an increase in the ranking of the blood donor role, greater expectations from others, and even more donations” [4].

Donors who are deferred are less likely to return to donate after the reason for the temporary deferral has passed [4, 16]. This is not surprising because deferral breaks the good feelings that might have developed about donation and makes future donation more difficult. Experiencing a reaction also reduces the likelihood of a donor returning [4, 14, 15]. This is because the donor begins to see himself or herself as someone who has trouble donating, and the reaction experience modifies any previous positive feelings about donation. Surprisingly, most multigallon donors report that they do not receive recognition for their donation, and the knowledge that a friend or relative was a blood donor did not make them more likely to donate [9]. These observations are consistent with the general view that the initial donation is motivated primarily by external factors and continued donation primarily by internal factors [32].

A disconnect exists between blood supply shortages and demographic reports that there are actually more eligible blood donors in the United States [33]. Simply put, it should be easier to meet the blood unit demands of the US medical system. However, experiences have shown that 12 million units in 2017 were donated by 9 million donors, representing 4.8% of the of the population eligible to donate. For many reasons, from demographics to logistics, many potential donors do not present to donate [33].

Donors are also more time conscious and desire a shorter (or more efficient) donor experience. Long wait times and screening may deter some from many blood drives. Blood collectors are looking at more self‐directed donor screening and additional software changes to decrease donor wait times.

Perhaps the most contentious area affecting continued donation may be iron depletion of blood donors. This is a widely debated area, with some medical directors arguing for more stringent monitoring of donor iron loss and others suggesting that we maintain the status quo. A review by Zalpuri et al. [34] addresses existing literature from 12 studies, regarding whole blood donors and health consequences from iron deficiency. The authors did note a high prevalence of iron deficiency among whole blood donors. The studies were much more conflicting as to what symptoms or conclusions could be drawn.

One confounding factor was that there is a lack of universally representative iron parameters for iron deficiency. Another confounding issue is that replenishment of hemoglobin and ferritin levels across the population of whole blood donors is widely varied, making comparisons between studies difficult. Ultimately, the effect of blood donation and subsequent iron deficiency (or transient deficiency) on overall quality of life could not be found [34].

Because blood donation is not done in private, it is by definition a “social” act [4]. It is not surprising that social factors and issues have a strong influence on blood donation. Social norms of the community affect donation behavior. For example, general publicity about blood donation in the community creates the perception that blood donation is an active part of the community, thus setting the stage for positive decisions by individuals to donate. This, together with “intrinsic” motivational appeals, builds a community norm for blood donation.

Volunteerism plays a major role in blood donation. A sense of social connection is gained, a feeling of helping others, and a history of volunteerism in the family or during their school years characterize blood donors [10].

The differing factors of social media’s influence on blood donation cannot be understated [35]. Most blood collection centers now have a dedicated strategy for social media representation and recruitment. Many centers turn to these media in times of inventory crisis, to contact engaged donors to turn out to drives and fixed sites. Because centers are doing with less financially, they can get messages out to donors in large numbers, many times at no cost. This is especially useful in expanding drive hours, or in the event of adverse conditions closing or canceling a drive or closing a center (early).

Blood donors are more likely to have had family members who were blood donors [4]. It is not clear whether blood use by a relative or close friend influences the likelihood that one will be a blood donor [6].

Blood is collected in both fixed and mobile sites. Fixed sites are facilities that are permanently outfitted to serve as a blood donation center. These sites are usually within the blood center or hospital but may be in freestanding locations, such as office buildings or shopping malls. The proportion of blood that is collected in fixed sites is not known and may vary greatly based on different blood centers’ collection strategies. In the Southern parts of the United States, mobile collections operations may predominate based on favorable logistic and climate conditions. A very large portion of the US blood supply is collected in mobile sites. A mobile site is a location that usually serves a purpose other than blood donation. Examples are offices, high schools, social clubs, churches, colleges, manufacturing companies, public buildings, or shopping malls. At the mobile site, or “bloodmobile,” all of the equipment and supplies necessary for blood collection are portable and are brought in for a few hours or days for the blood collection activity, or is a bus specially outfitted for blood donation. Donors at mobile sites are more likely to be first‐time donors, giving under social pressure, and thus with less internal motivation to donate, and they are more likely to experience a reaction or less‐than‐optimal experience [4]. However, the influence that these settings have on the likelihood that an individual will donate or will have a good experience and be willing to donate again is not well understood. There are differences between those who donate at fixed sites and those who donate at mobile locations [4]. Donors at fixed sites report more internal motivation, whereas those at mobile sites report more external motivation. This would be consistent with the structure of mobile sites, which are usually arranged around a blood “drive” of some sort involving a community group or a particular need, thus providing the “external” motivation. At fixed sites, the donor is usually called by blood center staff and the donation scheduled as part of the general ongoing blood collection activity, but there is no relation to a particular community or social group or patient.

Different types of organization are involved in collecting blood and providing the nation’s blood supply (see Chapter 2), and these may influence people’s willingness to donate. Such preferences could be because of the nature of the organization or the individual donor’s motivation. One major difference among organizations is hospital‐based donor programs versus community‐based freestanding blood centers. Because the community‐based blood center serves multiple hospitals, the organization (and, by extension, a donation made to it) carries an image of service to the general medical community, along with a feeling of community pride and allegiance. The nature of the community organization may also influence the individual’s willingness to donate. About half of the blood collection in community centers is carried out by the American Red Cross. The other half of blood collection is performed by freestanding organizations whose mission is the provision of blood services. In contrast, a hospital‐based program is associated with a specific medical center and can take advantage of the image of that center and its physicians, programs, and patients. Although there are no definitive studies, it seems likely that these factors influence the types of donor and their motivation for donating to different organizations. The differences between organizations involved may also affect the setting in which the blood is collected, and thus may indirectly influence the donors or their motivation. For instance, hospital‐based donor programs are more likely to use fixed sites for blood collection. Although community‐based blood centers use some fixed sites, they use mobile sites more extensively than hospital programs.

A variety of incentives, ranging from small trinkets, such as key chains, coffee mugs, or T‐shirts, to tickets to events to cash, have been offered to donors in hopes of motivating them to continue to donate. In almost every study worldwide, paying donors results in donors with a higher likelihood of transmitting disease [32, 36]. Thus, organizations such as the American Association of Blood Banks, the American Red Cross, the International Society for Blood Transfusion, the World Health Organization, and most countries that have a national blood policy stipulate that blood for transfusion be obtained from volunteer donors. The definition of volunteerism in blood donation is whether the incentive is transferable, refundable, or redeemable, or whether a market for it exists [37]. If none of these applies, it is presumed that the incentive could not be converted into cash.

In some very specific situations, it is possible to pay donors without increasing the risks for transmissible disease [38, 39], although this is not recommended. Blood testing for cholesterol, prostate‐specific antigen, or blood “credits” may be an incentive for many donors [40, 41], and incentives help to attract first‐time and younger donors. Some blood banks have used a blood “credit” system in which nondonors are charged a higher fee for the blood as an incentive to replace blood used. This practice is no longer used in the United States, but in many countries with an inadequate blood supply, versions of this practice are used [42]. A plurality of strategies that would include various incentives has been proposed [43].

There has been some evolution here in the past few years, as blood shortages have become more commonplace and the overall recruitment of donors has become more complicated and costly. Discussions have begun to consider paid donors again, particularly platelet donors.

It is generally believed that the most effective way to get someone to donate blood is to ask directly and personally [4, 7, 44]. For instance, in one study comparing two recruitment techniques, the direct “foot in the door” approach was found to be superior to a general request to participate in a donor program [45]. When people were asked their reasons for not donating, the most common response was “no one ever asked” [7]. The wide variety of settings in which blood is collected may also affect an individual’s willingness to donate. Different motivations may apply to donation in different settings, or the setting may influence an individual’s willingness to donate. However, for either the fixed or the mobile site, substantial efforts are made to specifically ask the individual to donate and, if possible, schedule the donation. This request may be made by paid staff of the donor organization or by volunteers. It is not clear whether either type of individual is more effective. Many blood centers with large donor programs have implemented computerized calling systems that integrate the donor files with the donor’s history along with automated dialing systems to maximize the efficiency of the telephoning process.

Usually blood donors are asked to give to the general community blood supply. Sometimes donors are asked to donate blood for one or more specific patients. Newman et al. [46] found that these patient‐related blood drives were easier to organize, produced more blood, and left the donors and staff with a stronger sense of satisfaction because of the more personal nature of the experience.

Little structured social science research has been directed to the issue of minority involvement in the blood donation process. Some success in increasing blood donation by minorities has been achieved by involving more minority staff in the recruitment and blood donation process (M. Wingard, quoted in O’Brien [47]). Compared with Hispanic nondonors, Hispanic donors were found to be better educated, to be more likely to speak English, to have higher job status, and to be more likely to have parents who were donors [48]. The study concluded that there is a need for improved education for Hispanic donors about the safety of blood donation. With the general aging of the population and the extending of age limits for blood donation, donation has been found to be safe for older persons. However, there are no unique recruitment strategies targeted to older donors. Because more blood is collected at colleges and high schools, the materials and publicity are designed to appeal to that age group, and thus could be considered to be targeted to this population segment.

Another issue in donor recruitment is whether to devote more effort to recruitment of new donors or to maintaining existing donors. New donors add to the overall files and replace donors inevitably lost because of attrition or disqualification. Thus, it is essential to replenish the donor pool. However, once people are in the donation habit, strategies to encourage them to continue result in the collection of substantial amounts of blood for less effort than is required to recruit new donors. Therefore, the dilemma is not in choosing only one of these strategies, but in balancing the effort between them to maintain an adequate donor file and also to produce new donors with a reasonable amount of effort. In the interest of overall operational efficiency, there has also been a push to recruit donors to “right type, right technology”; for example, group O donors are guided toward whole blood or automated apheresis red blood cell (RBC) collections, because their RBCs are in highest demand, whereas group AB donors are guided toward platelets or plasma because their RBCs are often unused. Excess collections or outdated products are “red ink” to a blood collector.

Some blood centers have taken steps to identify donors based on self‐reported ethnicity data. This has helped to provide certain ethnicity‐associated RBC phenotypes for difficult‐to‐match blood recipients. Several high‐profile national calls for “rare blood types” have recently been serviced by centers who could provide ethnically matched donors. This may over time increase the prevalence of blood donation in these ethnic groups.

As cytapheresis became a widely used method of producing blood components and the procedures began to take a place in the more routine operation of blood centers and hospitals, attention was directed to structured donor recruitment programs. This has raised considerations in addition to those for whole blood donors. The cytapheresis procedure is longer and thus requires more of a time commitment. In addition, the side effects, the nature of adverse reactions to donation, and the donor medical assessment are different from whole blood donation. Thus, the types of people to be approached about donation, the information they would be given, and the strategy to be used to obtain the best decision from the donor and potentially the highest acceptance rate became topics of great interest.

A key step in the development of cytapheresis donor programs was a conference that was held to address the scientific, legal, and ethical issues [49]. Issues such as the cost‐effectiveness of platelet transfusion, individual rights, informed consent, donor decision‐making mechanisms, and personal autonomy were discussed in the context of plateletpheresis donation. The results of this conference formed a sound basis for the development of cytapheresis donor programs. Because of the additional burden of cytapheresis donation, frequent whole blood donors were selected as possible cytapheresis donors. The provision of informational materials was often sufficient to attract them into cytapheresis donation [50]. Platelet donation was not only an altruistic act of giving, but it also filled some personal needs of the individual.

Apheresis now is the major platelet production method (see Chapter 2) occurring thousands of times each day. Recruitment continues to focus on successful whole blood donors who are provided information about apheresis donation. Some blood centers position the apheresis collection area within the site of whole blood donors as a recruitment technique. Because apheresis donation can be done more frequently than whole blood, this is another incentive for some donors.

Because this is a special pool of donors, there has been some work to find the special traits that distinguish apheresis donors from the existing pool of whole blood donors. Several firms can use consumer and demographic data to analyze a collector’s donors to see which ones are most amenable to recruitment as apheresis donors.

With increasing use of bone marrow transplantation to treat a wider variety of diseases and with the success of the treatment improving, the lack of a suitable family donor for most patients became a major limitation in the availability of this treatment. The first successful transplant using marrow donated by a volunteer not related to the patient [51] opened the urgent need for large numbers of human leukocyte antigen (HLA)‐typed individuals who would be willing to donate marrow. A remarkable story unfolded, resulting in the establishment of the National Marrow Donor Program [52].

Initially it was believed that it might be improper or even unethical to ask volunteers unrelated to the patient to donate marrow. The risks of donation, the discomfort, the nature of the patient’s preparation for the transplant, and lethal consequences of withdrawal by the donor all contributed to an atmosphere in which this kind of donation seemed unlikely. However, the possibility was pursued in a small number of centers [52]. One of the major first steps was a conference sponsored by the University of Minnesota at which the legal, ethical, social, financial, and practical issues in unrelated volunteer marrow donation were discussed [53]. The involvement of two community blood centers added strength at this early stage because they were separate from the transplant centers and also because of the involvement of representatives of the general community as part of their governing boards. As these organizations began to consider establishing a marrow donor program, the results of the conference strengthened the belief that there were proper ways to inform people of the opportunity and the consequences of donation and to provide the opportunity to become a donor if desired [53]. The initial ethical principles involved respect for life, promotion of good, prevention of harm, justice, fairness, truth‐telling, and individual freedom [53].

Because of the extensive commitment required of donors, it was decided to approach multigallon blood donors and apheresis donors [54, 55]. This had the added benefit that most were already apheresis donors who had been HLA‐typed, and this avoided the cost of additional HLA typing. The “recruitment” involved providing an extensive description of marrow transplantation, the situations in which it was used, the results of transplantation, including actual survival statistics, the marrow donation process, and the steps that would lead up to marrow donation. The recruitment process drew heavily on the considerable experience of sociologic studies of families making the decision to donate an organ either to a relative or for cadaver transplantation [56, 57]. The informed consent process was given very heavy weight in the recruitment process [54]. Remarkably, about three‐fourths of the donors who were provided an extensive description of the marrow donor program elected to participate [54, 55]. Important factors in the donor’s decision whether to participate in the program were religion, experience with the medical system, and the spouse’s attitude regarding marrow donation [55].

Donor recruitment efforts were expanded to the general public. Although there was concern that people who had never donated blood would not be sufficiently well informed or willing to make the necessary commitment, general community appeals for donors resulted in the recruitment of donors who became as committed to the program as the cytapheresis donors [55]. The national marrow donor file has now grown to more than 10 million volunteers in the United States and many more worldwide. The extensive experience with marrow donation establishes the effectiveness of the recruitment process and the lifesaving impact of the therapy on patients.

Gary Bachowski MD, PhD

The blood supply system in the United States has developed along two main tracks (see Chapter 2). One involves nonprofit community, regional, and national blood centers that obtain cellular elements and plasma from whole blood or apheresis donations provided almost exclusively by unpaid volunteers. Most of these products are used directly for transfusion.

The other blood collection system involves large‐scale collection of plasma by plasmapheresis. This system consists of for‐profit organizations and almost all of this plasma comes from paid donors. This plasma is manufactured into plasma derivatives, such as albumin, coagulation factor concentrates, or intravenous immunoglobulin, and these are sold on the national and international market.

Whole blood is collected by venipuncture from healthy adults into plastic bags containing a liquid anticoagulant preservative solution. The whole blood is separated into red blood cells, plasma, and occasionally platelet concentrate (see Chapter 5). The plasma can be: (a) frozen and used for transfusion, (b) further processed into cryoprecipitate (to be used for transfusion) and cryoprecipitate‐poor plasma (which can serve as a raw material for further manufacture of plasma derivatives), or (c) provided as a direct source of raw material for subsequent manufacture of plasma derivatives. Modifications can be made to these components to obtain blood products that will be effective for specific purposes. A complete list of components that can be produced from whole blood and are licensed by the US Food and Drug Administration (FDA) is provided in Chapter 5. Although blood banks may distribute some plasma derivatives, most are distributed through manufacturers by hospital pharmacies. Blood centers also produce platelets, red cells, plasma, and granulocytes by apheresis (see Chapter 6) in which the component(s) of interest is (are) removed in a blood cell separator and the remaining blood is returned to the donor.

Because blood is considered to be a drug and is regulated under FDA law, most aspects of potential donor selection and the collection of blood are carried out under requirements established by the FDA. This chapter attempts to provide concepts and rationale for blood donor assessment and blood collection but does not refer to every specific FDA requirement. However, it should be understood that all of these activities must conform to FDA requirements, which can be found in the Code of Federal Regulations and various FDA guidelines. For blood banks that desire accreditation by the AABB (American Association of Blood Banks), the standards of that organization must also be followed. The Technical Manual of the AABB [1] is an excellent reference that provides details for much of the content of this chapter.

The selection process for blood donors is designed to ensure the safety of the donor and to obtain a high‐quality blood component that is as safe as possible for the recipient (Table 4.1). In general, 10–15% of presenting donors are either deferred or provide an unsatisfactory unit of blood due to short‐term deferrals (e.g., hemoglobin), long‐term deferral (e.g., malaria), permanent deferral (e.g., hepatitis B/C), disease marker reactive donations, or an unsatisfactory collection process [2–4]. The loss of these potential donors and donations has a huge impact on the blood supply [5].

A major factor influencing whether blood donors will make subsequent donations is their experience at each donation. Thus, it is important that the blood collection staff provide a warm, friendly, professional, and efficient environment in which the medical assessment and blood donation can take place.

When the donor initially presents at the donation site, identifying information is obtained for the permanent record. This includes name, address, telephone number, birth date, social security number (if allowed in that state), and previous donation history, including any names under which previous donations might have been made. To prevent iron depletion, individuals may donate a red cell unit no more often than every 56 days, or 112 days if they are giving a double unit by automated collection. At the time of registration, the prospective donor is given information about blood donation, transmissible disease testing, and factors or behaviors that would preclude blood donation. Information may also describe the agencies that are notified in the event of a positive test result for a transmissible disease. In obtaining the medical history, a staff member asks or reviews donor responses to questions about these factors. Either at the time of registration or before the blood unit is made available for distribution, the identity of each donor must be checked against a registry of individuals known to be unacceptable as blood donors [6]. Although this process is required by the FDA and is widely used throughout the United States, there has never been a thorough study to establish its value, and some registries do not share information that could limit effectiveness.

Table 4.1 Strategies for collecting safe blood.

There is no standard maximum age for blood donation. Most blood centers do not have a specific upper age limit and instead evaluate each donor individually. Elderly donors have more medical conditions and medications than younger donors, but they do not experience more adverse reactions to donation [7, 8]. Elderly donors have slightly decreased iron stores, especially if they have been regular donors [9–11], but they can safely contribute to the nation’s blood supply [12]. Although 18 years is typically the age at which individuals can take responsibility for their own actions, the lower age limit for blood donation is usually 17 years, and most states have passed laws that also allow donation of whole blood at the age of 16 with parental consent. These special laws dealing with blood donation enable high school students to donate. However, donor safety concerns regarding possible health effects of iron depletion in this age group have led some blood centers to self‐regulatory steps, such as longer minimal donation intervals (e.g., no more than two times per year) and prohibiting automated collection of double red cell units in females younger than 19 years [13].

The medical history is an extremely important part of the selection of donors because it can reveal reasons why donation might not be wise for the donor or reasons why the donor’s blood might pose increased risk for the patient. Because most blood organizations now use the computerized self‐administered history, the interview usually takes less than 10 minutes. Many blood organizations provide the opportunity for the donor to do this online in advance. In addition to obtaining responses to these specific questions (Table 4.2), the interviewer attempts to assess whether the donor is in good general health, is not under the influence of drugs, and is able to give informed consent for the donation. The interview must occur in a setting that provides privacy for the donor. Although complete visual privacy is not always possible, visual distractions should be minimized, and the donor’s answers must not be audible to others. The interviewer reviews the response in the computer‐assisted donor history and then asks specific questions. The varied levels of computer‐assisted donor screening seem to be acceptable to donors and may decrease errors [14].

An interagency task force developed a standard donor history questionnaire (DHQ) that is approved by the FDA (https://www.fda.gov/vaccines‐blood‐biologics/guidance‐compliance‐regulatory‐information‐biologics/biologics‐guidances) and is used as a template by most blood banks. There is supplemental material for the DHQ regarding responses to each question, together with a flow chart defining need for and duration of deferral (http://www.aabb.org/tm/questionnaires/Documents/dhq/v2‐1/DHQ‐v2‐1‐Implementation‐Toolkit.pdf). The DHQ can be self‐administered by the donor or combined with direct questioning and is easily put in a computer‐assisted format. The questions designed to protect the safety of the donor include those regarding medications and whether the donor has a history of heart or lung disease, present or recent pregnancy, recent donation of blood or plasma, or bleeding condition. Questions pertaining to recipient safety include inquiry to the donor’s general health; the presence of a bleeding disorder, Chagas’ disease (although the question is not helpful) [15], or babesiosis; the injection of drugs; blood transfusion; tattoo or ear or body piercing; organ or tissue transplant; travel to areas endemic for malaria, Ebola, or Zika; recent immunizations; contact with persons with hepatitis or other transmissible diseases; ingestion of medications, especially aspirin; or previous notice of a positive test for human immunodeficiency virus/acquired immune deficiency virus (HIV/AIDS).

Individuals who have spent more than 3 months in the United Kingdom from 1980 to 1996 are deferred because of possible exposure to the causative agent of variant Creutzfeldt–Jakob disease, as are those who have spent 5 or more years in selected European countries. Based on studies in the United States and Canada, which have modified restrictions, 1–2% donor loss has been estimated because some form of this question has been included on the questionnaire [16–18].

Table 4.2 Complete list of medical history questions for blood donors.

Source: Fung MK, Eder AF, Spitalnik S, Westhoff CM, eds. Technical Manual, 19th edn. Arlington, VA: American Association of Blood Banks, 2017.

Potential donors who have resided in or traveled to malaria‐endemic areas are deferred for 12 months. However, most transfusion‐transmitted malaria is associated with lengthy residence in malaria‐endemic areas rather than routine or short‐term travel, especially when short‐term travel is concentrated in tourist areas that may have little or no risk [19].

Several questions related to AIDS risk behavior include whether the potential donor has had sex with anyone with AIDS risk factors, that is, given or received money or drugs for sex, had sex with another male (for males), or had sex with a male who has had sex with another male (for females). One area of inconsistency that has been eliminated involved whether males had sex with another male (MSM) at any time since 1977 (when HIV is thought to have entered humans). Previously, deferral had been indefinite, but this has been changed to 12 months to be consistent with other risk deferrals, and the reference to 1977 was eliminated. When the FDA changed this guidance regarding MSM in late 2015, it also committed to studying the effects of these changes on HIV risk in the blood supply through the Transfusion‐Transmissible Infections Monitoring System (TTIMS), a collaborative effort of the FDA, National Institutes of Health, and several major blood centers [20]. Although US data for the initial period since the changes have not yet been published, reports from Canada suggest that risk will not be greatly altered and that models used to estimate risk have been accurate [21–23]. In any case, when more data are available it may facilitate consideration of additional policy changes being tried in other countries, such as shorter (3 or 6 months) MSM deferral, or using other criteria to assess blood donor HIV risk that eliminates the MSM question.

Transfusion recipients can theoretically harbor unknown infectious agents and perpetrate the cycle of transmissible disease, and so deferral of previous transfusion recipients has been considered. In one very large study, a previous transfusion history was found in 4.2% of donors. However, transfused and nontransfused donors had a similar incidence of positive viral screening tests and other deferrable risks [24], and thus receipt of transfusions is not a deferral criterion.

The medical history is an extremely effective part of ensuring the safety of the blood supply. For instance, the implementation of questions about behavior that would put potential donors at risk for HIV infection decreased the HIV infectivity of blood in the San Francisco Bay area by 90% even before the use of the HIV screening test [25]. One concern that remains even today has been that people who have engaged in high‐risk behavior might seek to donate blood to obtain a test for HIV. In some situations, this seems to be true. Of 30 HIV‐positive blood donors in Paris, 47% had known risk behaviors and 50% admitted to having donated to obtain a test for HIV [26]. In a larger study of HIV‐seropositive blood donors, their reasons for donating in spite of having participated in behavior that placed them at risk for HIV infection included failure to read carefully or comprehend the deferral information, group pressure, a desire to be tested, and belief that the testing would identify any infected blood [27]. Despite concerns raised by this study, overall, blood donors have a lower rate of transmissible disease test results than the general population.

Occasionally, situations arise in which the donor’s physician believes that donation would be safe, but the blood bank does not accept the donor. For instance, some medications may make the individual unsuitable as a blood donor because of the condition requiring the medication, while other medications may be potentially harmful to the recipient. Many other conditions must be evaluated individually by the blood bank physician, whose assessment of conformance with FDA regulations, which consider blood a pharmaceutical, may not always coincide with another physician’s view of the health of the potential donor.

Hereditary hemochromatosis is genetically determined. The use of phlebotomy to reduce iron stores and prevent progression of the disease continues to be the therapy of choice. Blood obtained by therapeutic phlebotomy of patients with hemochromatosis was not acceptable for transfusion when the pathogenesis of the disease was not understood. Approximately two‐thirds of patients with hemochromatosis are probably eligible as blood donors, and thus about 65% of the units drawn during iron‐depletion therapy would be suitable for transfusion. Since 2016, the FDA has allowed blood banks to collect units for transfusion from this population, although this resource has not become fully utilized. Previous survey estimates suggested this could provide 200,000 to 3 million units [28] of blood annually in the United States. Studies show that risk for a positive test for transfusion‐transmitted infections is not greater from patients with hemochromatosis than from regular blood donors, and a National Institutes of Health pilot program was able to include these patients as 7% of their donor population, who supplied 11% of red blood cell units for transfusion and research [29–31].

The physical examination of a potential donor includes determination of the donor’s temperature, pulse, blood pressure, weight, and hemoglobin. Each of these has FDA‐mandated limits. In addition, the donor’s general appearance and behavior are assessed for any signs of illness or the influence of drugs or alcohol. The skin at the venipuncture site is examined for signs of intravenous drug abuse, lesions suggestive of underlying disease, and local lesions that might make it difficult to cleanse the skin and thus lead to contamination of the blood unit during venipuncture.

There are weight requirements for donors because it is necessary to balance the amount of blood collected in relation to the donor’s estimated blood volume and also the amount of blood in relation to the volume of anticoagulant in the collection container. To integrate the volumes of blood collected with the weight ranges of donors, an arbitrary lower weight limit of 110 pounds has been established. There is no upper weight limit, although extremely obese potential donors may have other health problems or inadequate venous access that could preclude donation. The pulse should be regular and between 50 and 100 per minute, although potential donors who have a slower pulse related to involvement in an active exercise program may donate with approval of the transfusion medicine physician.

Although hemoglobin may still be estimated by a manual screening method in which a drop of blood is placed in a copper sulfate solution of a known specific gravity, in developed countries, automated microhematocrit is most often used, and in less well‐developed countries, a hemoglobin color scale can be used [32]. Noninvasive methods for hemoglobin are now available but have not yet become widely used. For any method, the recommended blood drop source is the finger, because blood from an earlobe puncture can have a falsely elevated hemoglobin [33, 34]. Factors that affect the rate of deferrals due to hematocrit are the proportion of female donors, smokers, African Americans in the donor population, altitude of the donation location, and source of blood sample (finger versus ear lobe). Because the hemoglobin fluctuates with temperature, being lower in hot weather, there may be an increase in deferrals because of low hemoglobin during the summer months [35]. Until recently, the same hemoglobin criterion was used for men and women (12.5 g/dL). This is within the normal range for Caucasian women [11.6–15.7 g/dL) but below the normal range for Caucasian men (13.3–17.2 g/dL). Most hemoglobin deferrals occurred in women, although many women with essentially normal hemoglobins have been deferred. In contrast, a hemoglobin of 12.5 g/dL may indicate mild anemia in a man. Although FDA guidance now recognizes that many women may safely donate with hemoglobin 12–12.5 g/dL, it also recommends that further, although unspecified, steps to prevent iron deficiency be taken if this lower cutoff is used because iron deficiency is prevalent in premenopausal women who are frequent whole blood donors [36, 37]. The screening hemoglobin values do not prevent iron‐deficient individuals (predominantly women) from donating [36, 38].

Low or absent iron stores occur in a significant percentage of frequent blood donors. Suggested approaches include further restrictions on the frequency of blood donation and/or providing iron supplementation. There is no uniform approach to donors deferred because of low hemoglobin. Approaches have included temporary deferral for 6 months, 3 days to 3 months, or variable length of deferral depending on the hemoglobin. There are no standard recommendations regarding serum ferritin testing and whether to provide iron supplementation or merely recommend this to the donors [39, 40]. Some blood centers have implemented programs to perform ferritin testing, which is considered a more reliable indication of iron status. These programs often focus on young donors, especially females who may be most susceptible to the effects of iron depletion [41, 42]. Two studies [43, 44] support the value of iron therapy in women without anemia.

Even in the absence of anemia, iron deficiency can have clinical effects, such as fatigue, decreased exercise capacity, and cognitive performance [45]. Strategies ranging from physician referral to providing educational material or even providing iron supplements have been tried, but no standard approach is in wide use. This has been an issue for years and could have major implications for donor availability [38, 39, 45].

There are several situations involving blood donation in which the blood may be collected by the donor center but will not be used as part of the community’s general blood supply. Examples of these include autologous donation, directed donation, patient‐specific donation, and therapeutic bleeding. In some of these situations, the FDA requirements for blood donation may not apply. However, if directed donations are not needed by the designated patient and would otherwise meet criteria for general blood supply use, it is possible for a hospital to make these units available for others to use.

The time during blood collection is another opportunity for the blood center staff to interact with the donor, to reinforce their professionalism, and to provide conditions that increase donor willingness to return for subsequent donations. In a way this becomes the first step in the recruitment of the donor for the next donation (see Chapter 3).

The first step in the collection process is labeling of all containers, tubes, and related materials. This is an extremely important step because it relates all tubes, specimens, documents, and components to the identity of the donor. Virtually all blood banks use bar‐coded labels that are intended to meet international industry standards for labeling (ISBT 128) consistent with FDA and AABB requirements [46]. Related tracking of specimens, test results, and individual components can be managed by computers using these labels. Computer systems are generally used to accumulate all data relevant to the individual donation to determine whether the components are suitable for transfusion and can be released into usable inventory. Thus, there are detailed and specific steps in the process at the donor bedside to ensure the accuracy of all labels.

Blood must be collected into FDA‐licensed containers, each of which is sterile and can be used only once. The containers are made of plasticized material that is biocompatible with blood cells and allows diffusion of gases to provide optimal cell preservation (see Chapter 5). These blood containers are combinations of multiple bags connected by tubing so that components can be transferred between bags without being exposed to air. This is referred to as a “closed system.” This system of separation of the whole blood into its components in a closed system thus minimizes the chance of bacterial contamination while making it possible to store each component under the conditions and length of time that are optimum for that component. Because some bacteria can enter the blood bag from skin at the venipuncture, most blood collection sets now contain a small pouch for diversion of the first few milliliters of blood, which is used for many standard tests. Diversion of the first few milliliters of blood collected can reduce the bacterial contamination rate from 46% to 71% [47, 48].

Several anticoagulant preservative solutions are available. The anticoagulants are various formulas of citrate solutions. The blood may be stored in these solutions and used for transfusion, or most of the supernatant may be removed and the cells stored in other “additive” solutions. The composition and effects of these anticoagulant and preservative solutions are discussed more completely in Chapter 5.

Blood is drawn from a vein in the antecubital fossa. The vein selected should be large enough to accommodate approximately a 16‐gauge needle. Careful selection of the vein makes the venipuncture quick and easy, thus providing good blood flow and a quality component but also minimizing the discomfort to the donor and making the donation experience as pleasant as possible. The choice of the vein will also minimize the likelihood of inadvertently damaging a nerve or puncturing an artery (see the later Adverse Reactions section). A blood pressure cuff is usually used to impede venous return and distend the vein.

To minimize the chance of bacterial contamination, the blood must be drawn from an area free of skin lesions, and the phlebotomy site must be properly cleansed (Table 4.3). It is not possible to sterilize the skin, but steps are taken to greatly reduce the level of skin flora. A one‐step skin preparation using a chlorohexidine solution in 70% isopropanol is now recommended. Alternatively, a two‐step prep—scrubbing with a soap solution, followed by tincture of iodine or iodophor complex solution—may be used [1, 49, 50]. Preference for the prep method is often dependent on any history of donor allergies or previous reactions to the scrub. The selection of the venipuncture site and its sterilization are very important steps, because bacterial contamination of blood can be a serious, even fatal complication of transfusion (see Chapter 16).

Table 4.3 General procedure: donor arm preparation for blood collection.

Source: World Health Organization. WHO Guidelines on Drawing Blood: Best Practices in Phlebotomy. Geneva: World Health Organization, 2010. © 2010 World Health Organization.

Most blood collection equipment uses 16‐ or 17‐gauge needles, and the entire set is closed and connected so that the needle is integral. The venipuncture is done with a needle that can be used only once to avoid contamination. The phlebotomist must be aware of the needle placement to minimize the likelihood of puncturing a nerve or artery.

Usually the blood container is placed on a scale, which may have a device to cut off the flow when the container reaches a set weight indicating that the desired volume of blood has been collected. The blood must flow freely and be mixed with anticoagulant frequently as it fills the container to avoid the development of small clots. Blood banks often use mechanical devices that continuously mix the blood and anticoagulant during phlebotomy. No more than 15% of the donor’s estimated blood volume should be collected, and the limit of 10.5 mL/kg body weight [1] is intended to meet this limit. In addition, the volume of blood in the container should be between 405 and 550 mL (i.e., 450 or 500 mL ± 10%). Thus, including specimens for testing, the amount of blood drawn could total 575 mL. Units containing 300–404 mL can be used for transfusion but must be labeled as low‐volume units. The amount of blood withdrawn must be within prescribed limits to be in the proper ratio with the anticoagulant, otherwise the blood cells may be damaged or anticoagulation may not be satisfactory (see Chapter 5).

The actual time for phlebotomy and bleeding is usually about 7 minutes and almost always less than 10 minutes. If the blood flow is slow, clots may form in the tubing before the blood mixes with the anticoagulant in the container. Although there is no FDA‐defined maximum allowable time for the collection of a unit of blood, most blood banks establish a maximum, usually no more than about 15 minutes. There is no difference in factor VIII or platelet recovery between units collected in less than 8 minutes versus those collected in 8–12 minutes [51]. Extremely rapid, pulsatile blood flow or the appearance of bright red blood may indicate an arterial puncture. This can be confirmed by feeling the pressure building in the blood container. An arterial puncture is nearly unmistakable because of the very rapid filling and pressure that develops in the blood container.

During blood donation, there is a slight decrease in systolic and a rise in diastolic blood pressure and peripheral resistance, along with a slight decline in cardiac output but little change in heart rate [52]. The regional cerebral oxygen saturation decreases significantly but still remains within the range of individual physiologic variation, while the cerebral tissue hemoglobin concentration increases significantly, probably because of an increase in cerebral blood volume, which appears to be the major compensation mechanism during acute blood loss to maintain cerebral oxygenation [53].

At the conclusion of blood collection, the needle is removed and the donor is asked to apply pressure to the vein in the antecubital fossa for at least 1 or 2 minutes. Many blood centers have a policy of asking the donor to raise his or her arm to minimize the venous pressure while pressure is applied to the vein. When there is no bleeding, discoloration, or evidence of a hematoma at the venipuncture site, the donor should be evaluated for other symptoms of a reaction to donation. If none is present, the donor can move off the donor table to the refreshment area. The donor should be observed during this time, because the movement into an upright posture may bring on lightheadedness or even fainting.

Many donor reactions, especially lightheadedness or syncope, may occur when the donor is having refreshments. Donors are advised to drink extra fluids to replace and maintain lost blood volume. The nature of the fluid is generally left to donor discretion, except that alcoholic beverages are not recommended. Alcohol is a vasodilator and may cause a shift of blood flow to the periphery, resulting in reduced cerebral blood flow and hypotension or fainting. Even after the loss of a few hundred milliliters of blood, some donors are subject to lightheadedness or even fainting if they change position quickly. Therefore, donors are also advised not to return to work for the remainder of the day in an occupation where fainting would be hazardous to themselves or others. Likewise, donors are also advised to avoid strenuous exercise for the remainder of the day [54]. This may also minimize the chance of hematoma development at the venipuncture site.

Reactions have been associated with approximately 4% of blood donations, although many either occur or are first noticed when the donor is off‐site, which complicates accurate reporting. Fortunately, most reactions are not serious [55–57]. Minimizing donor reactions begins with the selection of the site for blood collection, the staff training, the general treatment the donor receives from the staff, and the ambience of the blood collection situation. These factors are important because reactions increase when the blood collection situation is crowded, noisy, or hot, or when the donor endures a long wait. Donors who have reactions are more likely to be younger [58, 59], to be unmarried, to have a higher predonation heart rate and lower diastolic blood pressure, and to be first‐time donors or to have donated fewer times than donors who do not experience reactions [59].

Adverse reactions to whole blood donation can be categorized generally as those due to: (a) hypovolemia, (b) vasovagal effects, and (c) complications of the venipuncture (Table 4.4). The most common symptoms of reaction to blood donation are weakness, cool skin, diaphoresis, and pallor. A more extensive but still moderate reaction may involve dizziness, pallor, hypertension, hypotension, and/or bradycardia. Bradycardia is usually taken as a sign of a vasovagal reaction rather than hypotensive or cardiovascular shock, in which tachycardia would be expected. The vasovagal syndrome can have detrimental effects on blood donors and the blood supply [60, 61]. The most common cause of these symptoms is probably due to the psychological stress of the situation or to neurologic factors rather than hypovolemia caused by loss of blood volume. In the past, a common response to a donor reaction was to have the donor rebreathe into a paper bag. This is effective only if the lightheadedness is due to hyperventilation and reduced bicarbonate levels. Most reactions do not have this basis, and the paper bag may only add to the tension of the situation. This is not recommended as routine practice, but should be reserved for situations in which it seems clear that hyperventilation is a major part of the reaction. Other systemic reactions may include nausea, vomiting, and hyperventilation, sometimes leading to twitching or muscle spasms, convulsions, or serious cardiac difficulties. These kinds of serious reactions are rare. Several strategies have been used to reduce donor reactions, especially in populations of young, first‐time donors, such as 16‐to 17‐year‐old students, who are seen as important to building a future donor base [62]. Intervention strategies studied include predonation education, distraction, and additional water intake, which can reduce the rate of vasovagal reactions [63–65]. Minimizing donor reactions is very important because donors who experience adverse reactions are less likely to return [60, 66, 67].

Table 4.4 Adverse reactions to whole blood donation.

No clinically significant positive or negative effects have been proved for long‐term, even multigallon, donors of whole blood, although there has been interest in determining impact on areas such as cardiovascular health, occurrence of malignancy, and immunologic response. In recent years, taking precautionary measures to protect young donors from iron depletion has become an area of interest, because there are concerns regarding neurologic development of adolescent donors and possible sequelae if young females become pregnant [68, 69].

Although most reactions are mild, severe reactions defined as those requiring hospitalization can occur. These include seizures, myocardial infarction, tetany, and death. Popovsky [57] reviewed 4,100,000 blood donations and found very severe reactions in 0.0005%, or 1 per 198,110 allogeneic blood donations. The kinds of reaction included severe vasovagal reaction, angina, tetany, and problems related to the venipuncture site. Most reactions occurred during donation while the donor was at the donor site, although 6% occurred more than 3 days later. Reactions were more likely in first‐time donors. If this incidence is generalized to the total yearly donations of 15 million, approximately 75 such reactions may occur annually.

Because seizures may occur following blood donation, a history of seizures has disqualified donors in the past. However, donors with a history of seizures well controlled at the time of donation have not demonstrated greater likelihood of experiencing a reaction to donation than donors who never had seizures [70]. Questions regarding seizures are not a standard part of universal donor screening, and blood banks have a variety of policies regarding deferral if a history of seizures is given.

During venipuncture, the needle may accidentally strike a nerve. Injuries causing numbness or tingling, pain, and/or loss of arm or hand strength occur in 1 in 21,000–26,700 donations [71, 72] and implies that approximately 600 injuries may occur annually in the United States. Some of the donors developed a hematoma after donation, but it could not be determined whether the nerve damage was related to the hematoma or direct injury by the needle. One‐third of the injuries resolved in less than 3 days, but 2% lasted longer than 6 months and 6% resulted in residual mild localized numbness [72].

In a detailed anatomic study of 11 patients with injury to upper extremity cutaneous nerves after routine venipuncture, Horowitz [73] observed that nerve injury appeared secondary to direct trauma via “inappropriate” needle or bolused material near the nerves and outside the target veins. However, in 3 of 13 additional patients, the venipunctures were properly performed and atraumatic. He explored the anatomic relationships of superficial veins and cutaneous nerves at three common venipuncture sites in the 14 upper extremities of seven randomly chosen cadavers. Major branches of cutaneous nerves were superficial to and overlay veins in 6 of the 14 extremities studied. In multiple instances, nerves and veins were intertwined. He concluded that anatomic relationships between upper extremity superficial veins and cutaneous nerves are so intimate that needle–nerve contact during venipuncture is common. Because venipuncture‐induced nerve injuries are rare, factors other than direct nerve contact appear necessary for the chronic pain syndrome to occur.

Arm complications such as hematoma and/or arm pain occur in about 30% of donors [74]. A hematoma occurs commonly after blood donation even though the arm is inspected, and donors are advised to apply pressure to the area. Usually these hematomas are not serious, but they cause some local discoloration of the antecubital fossa. A more serious but rare complication is the development of a large hematoma often due to arterial puncture. This can cause pressure on vessels or nerves and injury in the antecubital fossa. Reports of symptoms suggesting this type of complication should be dealt with urgently by the blood center so that the donor can receive rapid attention and drainage of the fossa if necessary to prevent more serious injury. Although rare, deep vein thrombosis of the upper extremities has been reported as a complication of whole blood donation [75, 76].

Blood may be collected as part of therapy for diseases, such as polycythemia vera or hemochromatosis. Because the procedure is being performed as a therapy, these individuals are patients, not donors. Their medical assessment then is focused on determining that the phlebotomy is safe for the patient. The patients may meet all of the criteria for whole blood donation except for the presence of the disease for which they are undergoing phlebotomy. However, as described earlier in this chapter, blood collected as therapeutic bleeding is not routinely used for transfusion, although in recent years the FDA has allowed variances so that blood from patients with benign conditions, such as hemochromatosis or secondary polycythemia, may be distributed by blood centers for patient use.

The selection of donors for plateletpheresis, leukapheresis, and plasmapheresis uses the same general criteria used for whole blood donors [1]. Because of the unique nature of apheresis, there are some additional donor requirements that are based on the unique complications that may occur from apheresis, the nature of the procedures, and the fact that because few red cells are removed, donors can undergo cytapheresis more often than whole blood donation. The amount of blood components removed from apheresis donors must be monitored. To be consistent with whole blood donation, not more than 200 mL of red cells may be removed in 8 weeks. If for some reason, such as instrument failure, it is not possible to return the red cells to the donor, then the donation is treated as if it were a whole blood donation, and the donor cannot donate again for 8 weeks. For consistency with plasma donation, not more than 1,000–1,200 mL of plasma per week may be retained. When donors undergo apheresis more often than every 8 weeks, this is referred to as “serial” donation, and cumulative records must be maintained of the details of these donations, and the records must be reviewed periodically to assure that requirements related to red blood cells and plasma are met. The laboratory testing of donors and apheresis components for nonbacterial pathogens is essentially the same as for whole blood donation. Thus, the likelihood of disease transmission from apheresis components is similar to whole blood components.

In one study of 2,069 plateletphereses in 352 donors, or an average of six procedures per donor, the following important observations were made that formed the basis of subsequent FDA regulations for the selection and monitoring of cytapheresis donors: (a) among women, platelet counts averaged 12% higher than those of males; (b) about 3% of all donors had platelet counts less than 150,000/mL before their first platelet donation; (c) the preapheresis platelet count was the best predictor of the postapheresis platelet count; (d) if donors with a preapheresis count of less than 150,000 were excluded, only 13% of donations resulted in a postapheresis count of less than 100,000; (e) the platelet count decreased about 30% immediately after apheresis; (f) the platelet count returned to normal about 4–6 days after apheresis; and (g) there was a slight rebound in platelet count above the initial count about 8–11 days after apheresis. Although the decrease in platelet count varies with the procedure used, a decrease of 20–35% generally occurs and the platelet count returns to baseline levels about 4 days after donation [77]. The platelet count decreases less than expected based on the number of platelets collected [78] because platelets are mobilized during the apheresis procedure [79].

A platelet count is not necessary before the initial donation because the decrease in platelet count following donation is not so extensive as to create a risk for the donor. At least 48 hours must elapse between platelet donations. If donors are to donate more frequently than every 4 weeks, a platelet count must be done to ensure that it is at least 150,000/μL before a subsequent donation. The platelet count can be obtained before the donation, or a count obtained after a previous donation can be used. Platelet donors should not have taken aspirin or drugs that interfere with platelet function, or must wait the specified time interval for that drug before donating (e.g., 3‐day waiting period for aspirin).

Collection of platelets, granulocytes, lymphocytes, or stem cells by cytapheresis results in very little red cell loss. Thus, red cell depletion is not considered a possible complication of any individual collection unless there is an instrument malfunction. However, because apheresis collections can occur with high frequency (e.g., 24 plateletpheresis collections in 12 months), cumulative red cell loss from test sampling can cause anemia and low ferritin stores [80].

Because no more than 15% of the donor’s blood is extracorporeal at any time, there is no greater risk for blood volume shift than with whole blood donation. In addition, during apheresis, citrate and saline solutions are infused, replacing some of the lost blood volume. Thus, shifts in blood volume leading to hypotension are not a problem. Because of the administration of hydroxyethyl starch (HES) during leukapheresis as sedimenting agent, there was concern that a net increase in blood volume might occur because HES is also used as a blood volume expander. This could lead to hypertension or acute heart failure. The volume of HES administered ranges typically from 200 to 400 mL and, combined with the removal of approximately 50–200 mL of granulocyte concentrate, does not result in complications caused by excess blood volume.

Because cytapheresis donors can donate more often than whole blood donors, there are some complications that could result from multiple frequent donations. These involve depletion of cells or plasma proteins.

Platelet depletion is a concern if donors undergo frequent plateletpheresis during a short period, although this was not observed in 352 donors who donated an average of six times [77].

Because the HES used in granulocyte collection is a blood volume expander, some blood banks use lower blood pressure levels than those used for whole blood donors when selecting granulocyte donors. This is not a requirement, however. Granulocyte donors usually receive corticosteroids, and many also receive granulocyte colony‐stimulating factor (G‐CSF) to increase their granulocyte count and the granulocyte yield (see Chapter 6). Thus, donors should be questioned about conditions that might be exacerbated by corticosteroids. These include hypertension, peptic ulcers, cataracts, and diabetes. Because corticosteroids are given to granulocyte donors, donation frequency is limited to prevent complications. If frequent donation is required, it needs to be under the close supervision of a physician with written plans for monitoring the donor for side effects of accumulation of HES or cumulative effects of corticosteroids and/or G‐CSF.

If plasma is donated no more than every 4 weeks (infrequent donor), the donor assessment procedures are the same as for whole blood. The FDA limitations for plasma removal are no more than 800 mL of plasma at one donation depending on the donor’s weight. These volumes may be slightly different when semiautomated instruments are used. Donors may give again in 48 hours as for platelets, but not more than twice within a 7‐day period. For donors undergoing plasmapheresis more often than once every 4 weeks (frequent donor), the serum protein must be monitored and found to be within normal limits.

Hematopoietic cell transplantation now uses a variety of donors, such as unrelated marrow, peripheral blood stem cells (PBSCs), or cord blood. Transfusion medicine physicians are involved in this donor selection process. The criteria for whole blood and apheresis donation serve as the basis for donor selection, but these criteria may be modified because the advantage of a particular donor may outweigh a very small or theoretical increased risk of the cellular product. Criteria intended to protect the donor are less likely to be modified, but as new donation situations, such an unrelated marrow or cord blood, have arisen, donor selection criteria for each situation were developed.

The physical examination of cytapheresis donors is the same as for whole blood donation.

Adverse reactions in apheresis donors (Table 4.5) are similar in character to those encountered in whole blood donation. Although double red cell collections by cytapheresis are now common, most cytapheresis procedures carried out in normal donors are plateletpheresis. Because the required interval between double red cell donation is proportionally increased, the long‐term potential for anemia/ferritin deficiency is probably similar to whole blood donation, although acute changes with each donation are greater. Normal donors undergoing plateletpheresis may report an adverse reaction following up to 50% of procedures when asked; however, such reactions cause the procedure to be discontinued only 0.1–1.0% of the time [81]. These reactions are almost entirely due to citrate toxicity and can be alleviated by slowing the rate of blood return and thus the rate of citrate infusion.

Some potential complications of apheresis apply to all types of procedures because they have to do with the instrument or activities that are common to all types of procedures, while others are unique to certain apheresis procedures [81–83].

Vasovagal reactions are similar to those associated with whole blood donation, but may be reduced depending on the amount of volume replacement with the method. The symptoms include weakness, pallor, diaphoresis, bradycardia, cold clammy skin, lightheadedness or fainting, and, if severe, convulsions. The treatment is as described for whole blood donors. Because the donors are usually experienced whole blood donors, they rarely experience vasovagal reactions.

Table 4.5 Potential complications and adverse reactions to cytapheresis donation.

The anticoagulant used for plateletpheresis is citrate. Cardiac toxicity caused by calcium binding can occur quickly at a very low concentration while having little impact on in vivo anticoagulation. Bleeding due to citrate anticoagulation is not a problem for donors.

Elevations of blood citrate can cause paresthesias, muscle cramping, tetany, cardiac arrhythmia, and other symptoms. The plateletpheresis procedure involves the administration of citrate solutions to donors, resulting from the massive autologous retransfusion of 4–6 L of their blood may be withdrawn, passed through the instrument, citrated, and returned to them during the procedure. In a careful study relating the dose of citrate, symptoms, electrocardiographic changes, and ionized calcium [84] showed that when citrate infusion rates were maintained at less than 65 mg/kg/hour, donors did not experience symptoms or demonstrate electrocardiographic abnormalities. This has been confirmed in later studies [85, 86]. Donors with similar levels of hypocalcemia may demonstrate wide variability in symptoms. Using anticoagulant citrate dextrose formula A at a ratio of 1:8 with whole blood, many abnormalities were observed, including bradycardia (sometimes severe); supraventricular and ventricular premature contractions; right bundle‐branch block; ST segment elevation or depression; and tall, flattened, or inverted T waves. Some of the donors experienced nausea, vomiting, hypotension, fainting, or convulsions [87]. Even when less citrate is infused, the QT interval is almost always prolonged [88, 89]. Citrate reactions are managed by slowing the flow rate of the instrument and thus slowing the rate of citrate infusion. This is quite effective in eliminating these reactions, and most apheresis personnel are very aware of this process. Oral or intravenous calcium can also be used to reverse or prevent this condition. Citrate toxicity can also occur inadvertently if tubing is not properly placed in the pumps and the citrate solution is allowed to flow freely into the donor [90].

Because the extracorporeal volume of the cytapheresis instruments is small (usually less than 200 mL), hypovolemia is rare and these donors do not experience circulatory problems. This becomes a more significant consideration in small donors (e.g., children) or donors with very low hemoglobin levels, populations who could be undergoing therapeutic procedures.

Because the blood is actively pumped into the donor’s veins, there is the theoretical possibility that air could be pumped into the donor if air enters the system. Some of the early models of apheresis instruments contained bubble chambers connected to a device that stopped the pumps if the chamber became filled with air. Air emboli have occurred but without reports of serious consequences. Contemporary instruments do not contain safety devices to prevent air embolus, and so this complication remains a concern. Staff members must be aware of this possibility and ensure that containers and tubing sets do not develop leaks that would allow air to enter the system.

Hematomas may develop after removal of the needles used for apheresis just as after whole blood donation. There is no reason that this should be a more or less frequent complication than following whole blood donation. However, because blood is returned to the donor by active pumping, if the needle becomes dislodged, the blood will continue to be injected into the antecubital fossa under pressure, and a substantial hematoma may develop quickly. The signs of this are pain, discoloration, or oozing at the venipuncture site. If this occurs, the blood flow is discontinued immediately, pressure is applied, and the hematoma is managed as described for whole blood donation.

Because blood is pumped through tubing and centrifuges of various configurations, hemolysis is a theoretical complication due to constricted tubing or the geometry of the flow pathways. When this rare event occurs in practice, generally a defective collection kit is suspected [91, 92].

Plateletpheresis does not damage the donor’s remaining platelets, and the donor’s platelet function is normal after donation [93]. Removal of platelets equivalent to several units of the donor’s blood does not result in thrombocytopenia. In a rather dramatic example, a female donor underwent 101 donations during a 33‐month period, with donation frequencies ranging from once to three times weekly [94]. Her platelet count remained in the range of 135,000–430,000 during this time. In donors who undergo repeated plateletpheresis, the platelet count decreases somewhat more, but then stabilizes [78, 95]. Thus, it appears that platelets can be donated safely approximately every 2–4 days if needed.

Instruments and procedures have been improved to minimize the leukocyte content in the product, and thus also avoid potential complications of lymphocyte depletion in the donor. As a result, most plateletpheresis procedures today remove about 1 × 10⁶ to 5 × 10⁷ leukocytes. Loss of this number of leukocytes is very unlikely to lead to leukocyte depletion or any clinical effects on the donor’s immune function and has the advantage of producing a leukodepleted product. This is true even after serial collections completed in a relatively short period [96, 97]. However, in studies using the previously employed methods, significant lymphocyte depletion was observed together with decrease in total lymphocyte count and B and T cells, lower T4/T8 ratio, and reduced mitogen response [98–100]. Separate studies indicated that at least 10⁹ lymphocytes must be removed daily to observe a significant decline in lymphocyte count and at least 10¹¹ lymphocytes total must be removed over a short time and/or the individual’s lymphocyte count must be less than 500/μL for clinical immunosuppression to occur [97, 101]. The most recent studies show that although there is variability in lymphocyte loss in serial donors with the two most common collection instruments, the loss does not appear to lead to any clinical predisposition to infection [102–104]. Although one study suggests a possible increased risk of immunosuppression related infections [105].

The complications related to leukapheresis itself are not different from those in plateletpheresis, but donors receive HES, corticosteroids, and possibly G‐CSF that can cause additional problems. Although there are only a few studies of side effects in frequent granulocyte donors [106], experience with stem cell donors has also provided information about side effects [107]. Short‐term effects of HES include rashes and fluid shifts, while the effects of corticosteroids and G‐CSF are also well known and are discussed in Chapter 6. Although there have been concerns about long‐term effects, such as cataracts [108, 109] or malignancy [110], in repeat donors, these have not been confirmed in studies.

One unexpected risk from plasmapheresis, especially when done frequently for therapeutic purposes, is the development of anemia, which is probably due to the blood samples used for laboratory testing [111].

Because of the low level of circulating PBSCs in normal donors, donors receive the hematopoietic growth factor G‐CSF to mobilize PBSCs and increase the yield. G‐CSF is also often used, sometimes in combination with glucocorticoids, to increase yields for granulocyte collections. G‐CSF, itself, is associated with a high frequency of side effects and is responsible for most of the complications of the donation of mononuclear cells as a source of PBSCs [107].

Alesia Kaplan MD

Whole blood (WB) transfusion was a standard of care for military and civilian settings during the period between World War I and World War II. When the technology to manufacture the components became available and the need for transfusion component therapy grew with advancement of medicine, WB fell out of favor. WB had a limited use and mainly was used only for pediatric cardiothoracic surgery patients in the United States until recently [1–3]. In the past decade, a renewed interest in WB has emerged. This is due to a published military experience that showed successful use of blood products, including low titer O whole blood (LTOWB), for prehospital resuscitation [4, 5]. Military success was adapted for civilian trauma patients with severe, life‐threatening hemorrhage in prehospital and hospital settings. Retrospective data from military and civilian trauma patients indicates that LTOWB transfusion is associated with improved or noninferior survival compared with resuscitation with blood components [4–8]. Although secondary analysis of the prehospital air medical plasma trial showed that patients receiving red blood cells (RBCs) + plasma had the greatest mortality benefit [6], a prospective, randomized, controlled trial comparing mortality between LTOWB and standard therapy (1:1:1 component therapy) during air medical transport and through the early in‐hospital phase of care is being conducted [9]. Several authors pointed out that use of LTOWB in severely bleeding patients is associated with biological and logistical advantages (Table 5.1) [10–12]. WB has less anticoagulant preservative solution and higher hematocrit, number of platelets, and coagulation factors compared with a reconstituted unit of WB with three components (RBC, platelets, and plasma). Also, it provides more effective oxygen‐carrying capacity [10–12]. In addition, studies showed that WB stored at cold temperatures (1–6°C) has functional platelets that provide improved hemostasis [2, 13]. Logistically, WB simplifies resuscitation and accelerates the provision of all blood components needed for patients with severe hemorrhage. The future application of LTOWB in different phases of care and clinical indications are still being explored.

Interestingly, in less developed parts of the world, WB is usually used and not blood components because equipment to produce components may not be available. However, in these situations, given the kind of patients being transfused, WB may be the best use of limited blood transfusion resources. In addition, the use of rapid tests for human immunodeficiency virus (HIV), hepatitis C virus, hepatitis B virus, and syphilis make fresh WB available in those situations. Additional information on the current use of WB for transfusion is available in Chapter 11.

Table 5.1 Some advantages and disadvantages of whole blood versus blood component therapy used primarily for hemorrhagic shock resuscitation.

RBC, red blood cell; TEG, thromboelastography; WB, whole blood.

Despite growing use of WB in patients with severe hemorrhage, the majority of WB collected in the United States is separated into its components, and each component is stored under conditions optimal for that component. This makes it possible to retain all of the activities of the original unit of WB and results in a large number of different components being available for transfusion therapy (Tables 5.2 and 5.3).

This chapter describes the characteristics of blood products, their preparation, and storage. Clinical uses are described in Chapters 10 and 11.

WB can be collected in 450‐ and 500‐mL bags that contain citrate–phosphate–dextrose (CPD), citrate–phosphate–double dextrose (CP2D), or citrate–phosphate–dextrose adenin‐1 (CPDA‐1). WB collected in CPD and CP2D is stored for 21 days, and blood collected in CPDA‐1 is stored for 35 days at 1–6°C. No additional manufacturing step is required prior to issuing of WB. WB can be leukoreduced. There is one platelet‐sparing leukoreduction filter available in the United States (Imuflex WB‐SP, Terumo BCT). In the military, warm fresh WB is used. It is collected and stored at 22°C up to 24 hours. It can be stored at 1–6°C up to 48 hours (cold fresh WB). It is not approved by the US Food and Drug Administration (FDA) in the civilian setting because the results of infectious disease testing are not available at the time of transfusion. To mitigate risks of transfusion‐transmitted infectious diseases, military personal is tested prior to deployment and every 90 days during their deployment.

Table 5.2 Components produced by blood banks and the medical use of these components.

CMV, cytomegalovirus; HLA, human leukocyte antigen.

Table 5.3 Some of the products manufactured from whole blood subject to licensure by the US Food and Drug Administration.

AHF, antihemophilic factor; CPD, citrate–phosphate–dextrose.

The beginning of red cell preservation can be traced to Peyton Rous, who was later awarded the Nobel Prize for his work with viruses. Rous [14] and Turner showed that glucose delayed in vitro hemolysis. During the period between World Wars I and II, Mollison [15] in England developed an acidified citrate and glucose solution for red cell preservation, variants of which are the mainstay of present‐day preservatives. These solutions are composed of citrate for anticoagulation, dextrose for cell maintenance, and phosphate buffers (Table 5.4). WB or RBCs can be stored in these solutions for periods ranging from 21 to 35 days.

During red cell preservation, adenosine triphosphate (ATP) loss generally correlates with poor red cell viability, and addition of adenine at the beginning of preservation increases ATP and improves red cell viability [16]. 2,3‐Diphosphoglycerate (2,3‐DPG) also declines in stored red cells, and this is associated with increased affinity of hemoglobin for oxygen [17–19]. Thus, there was considerable interest in developing solutions that would maintain both ATP and 2,3‐DPG while allowing removal of the maximum volume of plasma for production of derivatives. It is possible to extend the duration of red cell storage by placing the red cells in special “additive” solutions containing various combinations of saline, adenine, phosphate, bicarbonate, glucose, and mannitol [20–23] (Table 5.5). These solutions provide better nutrients that maintain red cell viability, red cell enzymes, and red cell function, allowing red cell preservation for 42 days (Table 5.6).

Because most blood is separated into its components, the WB is collected into sets that involve multiple connected bags. The blood first enters the primary bag, where it is mixed with anticoagulant–preservative solution. After collection, the WB is kept at a temperature either between 1°C and 6°C or between 20°C and 24°C depending on the intended use of the unit (Figure 5.1). If RBCs and plasma are to be produced, the blood is kept between 1°C and 6°C. The blood can be placed in a regular blood storage refrigerator or special insulated containers that contain ice to maintain the 1–6°C temperature. If platelets are to be prepared from the WB, the blood must be maintained at room temperature (20–24°C) because exposure to cold alters the platelets. Maintenance of the blood at room temperature is done by placing the units in containers specially designed to maintain that temperature. It is recognized that the blood will not attain the temperatures of the storage containers (1–6°C or 20–24°C) for several hours, but the blood must be placed in the environment that will begin to bring the temperature of the blood to the desired storage temperature.

Table 5.4 Content of anticoagulant–preservative solutions (mg in 63 mL).

Source: Fung MK, Eder A, Spitalnik SL, Westhoff CM, eds. Technical Manual, 19th edn. Bethesda, MD: American Association of Blood Banks, 2017, p. 132. © 2017 AABB. Reproduced with permission from AABB.

CPD, citrate–phosphate–dextrose; CP2D, citrate–phosphate–double dextrose; CPDA‐1, citrate–phosphate–dextrose adenin‐1.

RBCs are the cells remaining after most of the plasma has been removed from WB. They must have a final hematocrit of less than 80% [24]. This blood component is often called “packed red cells” or “packed cells.” Usually the red cells and plasma are separated within 8 hours of collection, because for the plasma to be used as a source of factor VIII it must be placed in the freezer less than 8 hours after collection.Centrifugation is used when the red cells are being prepared within a few hours after collection, because usually this is done as part of a large‐scale operation, and speed is important. The centrifugation conditions (time and speed) are determined by the method being used to prepare the platelets or plasma. If platelets or fresh frozen plasma (FFP) are not being produced from the original unit of WB, the red cells can be separated from the plasma at any time during the storage period of the blood. If the unit of WB is allowed to remain undisturbed for several hours, the red cells sediment and the plasma can be removed. When sedimentation is used, the red cells are not as concentrated; as a result, the red cell unit has a lower hematocrit and less plasma is recovered. Because the plasma is valuable as a source for production of plasma derivatives, it is desirable to recover the maximum amount of plasma; therefore, sedimentation currently is not usually used to separate WB into its components. However, sedimentation can be used quite effectively when equipment for centrifugation is not available, such as in developing countries.

The unit of red cells has a volume of about 300 mL and will contain a minimum of 154 mL of red cells (405 mL × 38% hematocrit). Usually the red cell unit contains about 190 mL of red cells (450 mL × 42% hematocrit) and has a hematocrit of about 60%. The fluid portion of the unit (approximately 130 mL) is primarily the additive preservative solution, although about 20 mL of plasma remains from the original unit of WB. The characteristics of a unit of red cells stored in an additive are listed in Table 5.6 and the general changes in Table 5.7. Considerable emphasis has been put to understanding these changes and the potential clinical impact (see Chapters 11 and 16). One unit of red cells will increase the hemoglobin concentration and hematocrit in an average‐size adult (70 kg) by about 1 g/dL and 3%, respectively.

Studies of biochemical and morphologic alterations that occur during storage of RBCs have expanded to investigate not only the correlation between storage lesion and anticoagulant–preservative solutions but also donor‐to‐donor variability. In 2013, RBC‐Omics Recipient Epidemiology Donor Evaluation (REDS)‐III study was lunched [25]. One of the main objectives of the study was to determine whether genetic and biological variability of blood donors defines the quality of RBCs and their capacity to withstand cold storage temperatures. The study demonstrated an association between donor characteristics, such as sex, age, race/ethnicity, iron intake, and donation frequency, and in vitro hemolysis in RBC product [26–28]. A genome‐wide association study provided additional information on gene loci and association with hemolysis [27, 29]. Overall, the new way of thinking about “storage lesion” and RBC‐Omics paves the way for future studies.

Red cells are stored at 1–6°C for 21–42 days depending on the anticoagulant–preservative solution used. For optimum inventory management, most blood centers use preservatives that allow 42‐day storage. The end of the storage period is referred to as the expiration date or the “outdate.” The cells must be stored in refrigerators with good air circulation and that are designed for blood storage. Household refrigerators are not suitable. The temperature in the refrigerator must be monitored and should be recorded periodically (continuously is preferable), at least every 4 hours. There should be an alarm system to warn staff if the temperature moves outside the acceptable limits. When blood is transported to the patient care area for transfusion, it may be allowed to warm to 10°C and still be suitable for return to the blood bank and reissue to other patients [24, 30].

Table 5.7 Changes that occur during red cell storage: the storage lesion.

Source: Adapted from Hess JR. Measures of stored red blood cell quality. Vox Sang 2014; 107:1–9.

ATP, adenosine triphosphate; 2,3‐DPG, 2,3‐diphosphoglycerate.

Blood components must be maintained under proper storage conditions during transportation from the blood center to the hospital transfusion service. Various containers are available for this purpose, and these processes are standard and work well in developed countries. However, in developing or undeveloped parts of the world, usually these kinds of containers are not available and red cells may not be refrigerated or stored properly during this transportation. This is also an issue in military settings, where it also important that these containers be lightweight.

RBCs, frozen or deglycerolized, are the cells that have been stored in the frozen state at optimal temperatures in the presence of a cryoprotective agent, which is removed by washing before transfusion [24, 31]. The red cells must be frozen within 6 days after collection, and they can be stored for up to 10 years, although the AABB (formerly American Association of Blood Banks) Standards [24] do not include a standard for storage duration, and acceptable postthaw results have been found after storage at −80°C for 37 years [32–35]. The cryoprotectant commonly used is glycerol, which must be removed before transfusion to avoid osmotic hemolysis when the cells are transfused. The method of freezing and storage must preserve at least 80% of the original red cells, and at least 70% of those cells must survive 24 hours after transfusion.

Freezing of red cells is based on work from more than 50 years ago showing that glycerol protected human red cells from freezing injury [36], and that red cells preserved with glycerol were clinically effective [37–39]. From this work, “high‐” and “low‐concentration” glycerol methods were developed [40, 41]. These methods actually relate to the concentration of glycerol, which determines the nature of the freezing injury to the cells. When freezing is slow, extracellular ice forms, which increases the extracellular osmolarity, causing intracellular water to diffuse out of the cell and resulting in intracellular dehydration and damage [40]. This type of injury is prevented by solutes such as glycerol that penetrate the cell and minimize the dehydration [40]. Because the freezing process is slow, high concentrations of cryoprotectant, usually 40% glycerol, are required. Red cells preserved with this high concentration of glycerol can be stored at about −85°C, a temperature that is achievable by mechanical freezers.

Rapid freezing causes intracellular ice crystals and resulting cell damage [40]. However, because the freezing is faster, lower concentrations of cryoprotectant, usually about 20% glycerol, are effective [42]. This lower concentration of glycerol necessitates storage of red cells at a temperature of about −196°C, achievable only by using liquid nitrogen.

These two methods—with different freezing rates, concentrations of glycerol, storage conditions, and processes for removing the glycerol— involve different technologies [40, 42]. Technology development played a major role in making red cell freezing clinically available. During the 1970s, a disposable plastic bowl and semiautomated washing system were developed that greatly facilitated glycerol removal from high glycerol concentration red cells [43–45]. In the rapid‐freeze method, the concentration of glycerol is low enough that glycerol removal can be done by washing in ordinary blood bags; complex instruments are not required. To summarize, the high‐concentration glycerol method involves more simple freezing and storage but complex deglycerolizing procedures. The low‐concentration glycerol method involves complex freezing and storage but simple deglycerolizing procedures. Frozen deglycerolized red cells are composed of essentially red cells suspended in an electrolyte solution. Most of the plasma, platelets, and leukocytes have been removed either by the freezing, thawing, or washing step necessary to remove the glycerol cryoprotectant. Thus, the deglycerolized red cells have a 24‐hour storage period, which is a major factor in the logistics of their use. Frozen RBCs are used primarily for storage of rare RBC types [46].

Red cells must be frozen within 6 days of collection to provide acceptable posttransfusion survival. Red cells that have been stored longer than 6 days can be frozen if they are “rejuvenated” [47]. Rejuvenation restores metabolic functions after the red cells are incubated with solutions containing pyruvate, inosine, glucose, phosphate, and adenine followed by freezing [47]. This is a helpful strategy to freeze red cells in situations such as: (a) red cells found after 6 days of storage have a rare phenotype, (b) red cells donated for autologous transfusion but the surgery is postponed, and (c) rare phenotype red cells thawed but not used. The rejuvenation and subsequent freezing process is complex, expensive, and not widely used.

Washing is indicated for severe allergic reactions and for removal of potassium in large‐volume transfusion in pediatrics. The definition of washed red cells is rather vague. These are the red cells remaining after washing with a solution that will remove almost all of the plasma [24]. Thus, the requirements for this component do not specify the nature of the washing solution or the exact composition of the final component. Red cells can be washed by adding saline to the red cells in an ordinary bag, centrifuging them and removing the supernatant, or by using semiautomated washing devices, such as those used for deglycerolization [48–50]. Depending on the solution and technique used, the washed red cells may have a variable content of leukocytes and platelets. There is usually some red cell loss during the washing step, and the resulting red cell unit may contain a smaller dose of red cells than a standard unit. In general, the characteristics of washed red cells are the removal of approximately 85% of the leukocytes, loss of about 15% of the red cells, and loss of more than 99% of the original plasma [48–50]. Because the washing usually involves entering the storage container, the washed red cells have a storage period of 24 hours at 1–6°C.

Leukocyte‐reduced red cells are cells prepared by a method known to retain at least 80% of the original red cells and reduce the total leukocyte content to less than 5 × 10⁶ [24].

The blood filters used for routine transfusions have a pore size of 170–260 mm. They filter out clots and fibrin strands but do not effectively remove leukocytes. During the 1960s and 1970s, it was recognized that leukocytes were important in the pathogenesis of febrile nonhemolytic transfusion reactions and could cause alloimmunization, which would later interfere with organ transplantation or platelet transfusion (see Chapter 16). Thus, considerable interest developed in removing leukocytes before transfusion. Early methods involved centrifuging the red cells (either upright or inverted); sedimenting red cells with dextran or hydroxyethyl starch; filtration with nylon or cotton wool, which removed only granulocytes [51]; or washing, freezing, and deglycerolizing [50]. These methods removed from 65% to 99% of the original leukocytes and from 5% to 20% of the original red cells. A huge body of literature developed describing the advantages and disadvantages of the different methods and some of the clinical effects of their use. Although they are of historical interest, these studies are not described extensively in this chapter because the methods are not used today. Leukodepletion continues to be a major issue in transfusion medicine because even more adverse effects of leukocytes contained in blood components have been identified (Table 5.8). The consequences of these effects are described in more detail in Chapter 16. As these adverse effects of leukocytes have been more extensively described, the technology for producing leukodepleted red cells has evolved to provide more extensive leukocyte depletion than was possible using earlier methods [52].

Clinical and animal studies suggested that red cells intended to prevent febrile nonhemolytic transfusion reactions must contain fewer than 5 × 10⁸ leukocytes, and those intended to prevent alloimmunization contain fewer than 5 × 10⁶ leukocytes [24]. The latter requires removal of about 99.9% of the leukocytes. Sophisticated filters have been developed to accomplish this.

The filter material may be modified to alter the surface charge and improve the effectiveness. The mechanism of leukocyte removal by the filters currently in use is probably a combination of physical or barrier retention and also biological processes involving cell adhesion to the filter material.

Because leukocytes are contained in red cell and platelet components, filters have been developed for both of these components. Filters are available as part of multiple‐bag systems, including additive solutions, so that leukocytes can be removed soon after collection and the unit of WB converted into the usual components. Filtration removes 99.9% of the leukocytes, along with a loss of 15–23% of the red cells [53]. Thus, bedside leukodepletion is not used. Filters fail to achieve the desired leukodepletion from 0.3 to 2.7% of units. Red cell components from donors with sickle cell trait often occlude white cell reduction filters.

It appears that febrile nonhemolytic transfusion reactions are caused not only by leukocyte antigen–antibody reactions but also by the cytokines produced by leukocytes in the transfused blood component (see Chapter 16). This would be more effectively prevented if the leukocytes were removed immediately after the blood was collected, avoiding the formation of cytokines. This is referred to as “prestorage” leukodepletion. Filtering the red cells at the bedside at the time of transfusion has the advantage of not requiring a separate blood bank inventory, but the disadvantage of allowing cytokines to accumulate during blood storage, thus being less effective in preventing febrile transfusion reactions (see Chapter 16). Also, bedside filtration is not as effective in removing leukocytes as filtration in the laboratory under standardized conditions and with a good quality‐control program [53]. Because the leukocyte content of the depleted units is very low, the usual methods for leukocyte counting are not accurate [53–55]. The Nageotte chamber and flow cytometry are used for this quality‐control testing [53, 55].

Table 5.8 Established or potential adverse effects of leukocytes in blood components.

HTLV‐I, human T‐lymphotropic virus I.

FFP is plasma separated from WB and placed at −18°C or lower within 8 hours of collection [24]. Fresh plasma may be frozen by placing it in a liquid freezing bath composed of ethanol and dry ice, or between blocks of dry ice, or in a mechanical or a blast freezer. The unit of FFP has a volume of about 200–250 mL and contains all of the coagulation factors present in fresh blood. FFP can also be produced as a by‐product of plateletpheresis, and this may result in a unit of FFP with a volume of about 500 mL, often called “jumbo” units of FFP. These can be stored or separated into two separate products. The electrolyte composition of FFP is that of freshly collected blood and the anticoagulant solution. FFP is not considered to contain red cells, and so is usually administered without regard to Rh type. However, there have been occasional rare reports suggesting that units of FFP contain a small amount of red cell stroma that can cause immunization to red cells [56]. Because it contains ABO antibodies, the plasma must be compatible with the recipient’s red cells. The number of leukocytes in FFP depends on the centrifugation procedures used for preparation.

FFP is stored at −18°C or below and can be stored for up to 1 year after the unit of blood was collected. Although there is no defined lower temperature for FFP storage, freezers capable of maintaining very low temperatures, such as −65°C, are not usually used for storage of FFP because these freezers are expensive to operate and there is no reason to keep the FFP that cold.

Twenty‐four‐hour frozen plasma (FP24) is plasma frozen more than 8 and less than 24 hours after collection. It contains normal amounts of factor V but only an average amount of about 55–75% of factor VIII [31]. Despite this lower coagulation factor VIII level, 24‐hour frozen plasma (FP24) is often used interchangeably with FFP (see Chapter 10).

FFP and FP24 are usually thawed in a 37°C water bath in an overwrap. However, it takes about 15–20 minutes to thaw one or two units, and someone must occasionally manipulate the unit to speed thawing by breaking up the pieces of ice. This time requirement is a substantial difficulty when FFP is needed for actively bleeding patients. Several approaches have been used, including larger water baths and water baths with agitating trays so that staff members do not need to manipulate the units. Another more promising approach is the use of microwave ovens for thawing FFP [57, 58]. The concern with microwave thawing has been the uneven energy distribution within the unit of FFP and resulting “hot spots” and damage to proteins. As microwave devices have improved, it appears that these problems have been overcome. After thawing, FFP or FP24 can be relabeled as thawed plasma (TP) and stored for up to 5 days at 1–6°C. Upon thawing, factor VIII and protein C levels are lower in FP24 than FFP, but there are adequate coagulation factor activities to maintain hemostatic effectiveness [59]. By day 5, factor V levels are about 60% and factor VIII levels 40–70%. Thus, as a source of coagulation factor replacement, it is best to use the TP within 24–48 hours. Five‐day storage makes it possible to maintain a stock supply of TP for emergency use in massive transfusion or urgent correction of warfarin therapy (see Chapters 10 and 11).

Plasma from a unit of WB can be removed at any time during the storage period of the WB unit or up to 5 days after the unit outdates. This plasma can be stored for up to 5 years at −18°C or lower. Because it was not frozen within 8 hours after the WB was collected, plasma is not a satisfactory source of coagulation factors V and VIII. Although other coagulation factors are present because the plasma is removed from the WB after several days of storage, the electrolyte concentrations of the plasma will reflect those of stored WB. Liquid plasma is becoming more common because it has a longer shelf life compared with TP. It does not need to be thawed and is used as a “bridge” to TP for initial treatment in massively hemorrhaging protocols [60].

Coagulation factor VIII is a cold insoluble protein [61]. Pool and Shannon [62] took advantage of this to develop a method to recover most of the factor VIII from a unit of WB in a concentrated form. Cryoprecipitate is the cold insoluble portion of FFP that has been thawed between 1°C and 6°C. The cold insoluble material is separated from the thawed plasma at 1–6°C immediately and refrozen within 1 hour. Although there are no specific requirements for the volume of a unit of cryoprecipitate, it is usually 5 mL or more, but less than 10 mL. The cryoprecipitate units must contain at least 80 units of factor VIII and 150 mg of fibrinogen [24]. Cryoprecipitate is not a suitable source of coagulation factors II, V, VII, IX, X, XI, and XII [63]. Several factors influence the content of factor VIII in cryoprecipitate, including the blood group of the donor (group A is higher than group O), the anticoagulant (CPD is higher than acid–citrate–dextrose), the age of the plasma when frozen, and the speed of thawing the FFP [64]. Cryoprecipitate also contains fibrinogen and von Willebrand factor, and with the availability of coagulation factor concentrates these are the primary uses of cryoprecipitate. Each bag of cryoprecipitate contains about 250 mg of fibrinogen [63]. Cryoprecipitate is stored at −18°C or below and can be kept for up to 1 year.

Cryoprecipitate is thawed at 37°C, usually in a water bath. Care must be taken to ensure that the water bath is not contaminated and that the bags of cryoprecipitate are placed inside another bag (overwrap) to minimize the chance of contamination. When using cryoprecipitate, it is customary to pool several bags so that only one container is sent to the patient care area for transfusion. Some blood centers pool several bags of cryoprecipitate before freezing them; this is more convenient for the transfusion service because it eliminates the need to pool individual bags of cryoprecipitate after they are thawed. After thawing, the cryoprecipitate must be maintained at room temperature to avoid reprecipitation of factor VIII.

Table 5.9 Platelet additive solution component concentration (mM).

Sources: Modified from Gulliksson H. Platelet additive solutions: current status. Immunohematology 2007; 23(1):14–17; Alhumaidan H, Sweeney J. Current status of additive solutions for platelets. J Clin Apher 2012; 27:93–98; Vermeij J. Methods for preparing platelet products. WO 2016/014854 A1. Geneva: World Intellectual Property Organization International Bureau, January 28, 2016.

^a Currently the only platelet additive solutions approved for use in the United States.

The official term for this component is platelets. These are platelets suspended in plasma or platelet additive solution (PAS) (Table 5.9) prepared by centrifugation of WB. Platelets may also be produced by cytapheresis (see Chapter 12). A unit of WB‐derived platelets must contain at least 5.5 × 10¹⁰ platelets [24]. Although there is no required volume, these units usually have a volume of about 50 mL to maintain viability and function during storage.

To prepare a dose of pooled platelets, 4–6 units of WB‐derived platelets are pooled together in an open system. After platelet pooling in open system, the platelets have a short outdate of 4 hours at room temperature. In addition, these platelet products are tested for bacterial contamination prior to issuing with point of care testing [65]. These platelets can be leukoreduced and irradiated if it is required based on the patient’s diagnosis. Acrodose platelet is an alternative technology for pooling platelets in the closed system [66]. Acrodose platelets are pretested for bacterial contamination, do not require pooling in the hospital blood bank, and can be issued in emergency situations immediately without further manipulation. Acrodose platelets can be stored for a total of 5 days at room temperature.

WB‐derived and apheresis platelets can be suspended in PASs. Advantages of PASs include reduction in allergic transfusion reactions, possibly TRALI and ABO‐mismatched hemolysis [67–69]. PAS also is used to mitigate deleterious effects of pathogen‐inactivated technology and can potentially improve viability of platelets and extend their days of storage. There are multiple PAS products on the European and US markets for WB‐derived and apheresis platelets.

There are two methods for preparing platelets from WB: the platelet‐rich plasma (PRP) method and the buffy coat method (Figure 5.3) [70]. In the United States, platelets are prepared using the PRP method; in Europe and Canada, the buffy coat method is used [70, 71]. The PRP method uses low g‐forces (“soft” spin), and the PRP easily separates from the red cells [72] within 8 hours after blood collection. The PRP is transferred into a satellite bag to separate it from the red cells (Figures 5.2 and 5.3). The PRP is then centrifuged at higher g‐forces (“hard” spin) and the platelet‐poor plasma is removed, leaving a platelet concentrate and about 50 mL of plasma (Figure 5.3). After the plasma is removed, the platelet concentrate is left undisturbed or, preferably, placed on the platelet storage rotating device for 1 hour to minimize platelet damage and allow for spontaneous resuspension [73]. In the PRP method, the first step is a soft spin and the second step is a hard spin (Figure 5.3); because of the soft spin, about 20% of the plasma and 20–30% of the platelets remain with the red cells [70]. Another 5–10% of platelets are lost during the second centrifugation step when the PRP is converted to a platelet concentrate. Thus, the PRP method yields about 60–75% of the original platelets, a red cell unit containing about 40 mL of plasma, and about 50% or more of the leukocytes in the original unit of WB. The disadvantages of this method are the loss of some plasma that could be used for fractionation and the high leukocyte content of the platelets.

Platelets prepared by either method can be stored in either plasma or PAS. Platelets stored at 20–24°C maintain functional effectiveness for several days [13, 77–80]. Many variables affect the quality of platelets during storage. In addition to temperature, these other variables include the anticoagulant–preservative solution, storage container, type of agitation, anticoagulant, and volume of plasma [72, 81–83]. Gentle horizontal agitation is preferable to end‐over‐end agitation [83]. If continuous agitation is interrupted, platelets stored for up to 5 days maintain appropriate in vitro characteristics for up to 24 hours of interruption of agitation [84]. The composition, surface area, and size of the storage container influence the ability for carbon dioxide to diffuse out and oxygen to enter the platelet concentrate, and storage containers specifically designed to optimize platelet quality are now used routinely [85, 86].

Maintenance of the pH greater than 6.0 is the crucial factor indicating satisfactory platelet preservation. This combination of storage container, agitation, preservative solution, temperature, and the use of about 50 mL of plasma provides satisfactory preservation of platelets for up to 7 days [85, 87]. However, several instances of bacterial contamination of platelet concentrates stored for this period were reported [87, 88], and the storage time was reduced to the 5 days currently used [24]. The problem of bacterial contamination still exists (see Chapter 16), although recently with additional point of care testing for bacterial detection, the FDA approved storage of apheresis platelets up to 7 days [89] (see Chapter 7). The storage container needs to be FDA approved for apheresis platelet storage up to 7 days. In addition, large‐volume delayed sampling and secondary cultures can be used to extend platelet storage to 7 days [89].

Several platelet concentrates are usually pooled to provide an adequate dose for most patients (see Chapter 10). For some patients, the volume of plasma in the final pooled component is too large, and plasma must be removed prior to transfusion. This involves another centrifugation step after the platelets have been pooled that causes a loss of 15% to as much as 55% of the platelets [90, 91].

The leukocyte content of the platelet concentrates is an important issue (see Chapters 10, 11, and 16). The conditions used to centrifuge WB influence the leukocyte content of the platelet concentrate, but most platelet concentrates contain 10⁸ or more leukocytes. Filters are available that remove most of the leukocytes in the platelet concentrate. The filters can be used at the bedside, or preferably before the platelets are stored. All platelets should be leukodepleted.

Filters are available for leukodepletion of platelets, as well as red cells. This is necessary if it is hoped to prevent alloimmunization or cytomegalovirus transmission in patients receiving platelet transfusion [53]. The platelet filters result in a loss of about 20–25% of the platelets and have a rate of failure in achieving fewer than 5 × 10⁶ leukocytes of about 5–7% [53].

Granulocytes for transfusion are prepared by cytapheresis (see Chapter 6). Some investigators have prepared granulocytes from fresh WB by sedimentation with hydroxyethyl starch to obtain doses of 0.25 × 10⁹. This is below the 1–3 × 10⁹ desired for transfusion even to a neonate [92]. The possibility of obtaining granulocytes from units of WB is usually raised in a crisis; the blood bank often does not have procedures to prepare the cells, and it is not possible logistically to test the blood for transmissible disease. Thus, preparation of granulocytes from units of fresh WB is not recommended.

The techniques and clinical indications for irradiating blood components are described in Chapter 10.

Hematopoietic stem cells are being obtained from bone marrow, peripheral blood, and cord blood. Collection of marrow and umbilical cord blood is described in Chapter 19 and peripheral blood stem cells in Chapter 6. Stem cells from these different sources are undergoing an increasing variety of cellular engineering methods that produce new blood components with exciting therapeutic potential.

Procedures for the fractionation of plasma were developed during the 1940s in response to World War II (see Chapter 1). A large pool of plasma, often up to 10,000 L or 50,000 donor units, is processed using cold ethanol fractionation. In cold ethanol, different plasma proteins have different solubilities, which allow their separation. This large‐scale separation and manufacturing process results in the isolation of several proteins from plasma that are prepared for therapeutic use. These are called “plasma derivatives” (Table 5.10). The major derivatives have been albumin, immune serum, immune globulin, and coagulation factor VIII concentrate. Until the late 1980s, techniques were not available to sterilize some blood derivatives after manufacture. Thus, because of the large number of units of donor plasma in each pool, the chance of contamination of the pool with viruses (i.e., hepatitis and HIV) was high and the risk for disease transmission from these nonsterilized blood derivatives was high (see Chapter 17). This risk was accentuated because much of the plasma that serves as the raw material for the manufacture of blood derivatives was obtained from paid donors, a group known to provide blood with an increased likelihood of transmitting disease [93, 94]. Initially, only albumin and immune globulin carried no risk for disease transmission—albumin because it was sterilized by heating, and immune globulin because none of the known infectious agents was contained in that fraction prepared from the plasma. Because of the recognition of the high risk for disease transmission by coagulation factor concentrates, methods were developed to sterilize them [95, 96].

Concerns arose about the possible transfusion transmission of the agent responsible for variant Creutzfeldt–Jakob disease because this infectivity is not inactivated by most conventional methods. Fortunately, it appears that the prions associated with variant Creutzfeldt–Jakob disease do not partition with the therapeutic proteins during plasma fractionation [97, 98].

Although coagulation factor concentrates were known to transmit hepatitis when they first became available, the risk has been reduced over the years by improvements to the donor history, the addition of laboratory tests for transmissible agents, and the introduction in the mid‐1980s of methods to treat the concentrates to separate and inactivate viruses [95, 96, 99]. The major methods of viral inactivation for plasma‐derived concentrates are: (a) dry heating, in which the sealed final vial is heated between 80°C and 100°C; (b) pasteurization, in which the concentrate is heated to 60°C while still in solution before lyophilization; (c) vapor heating, in which the lyophilized powder is exposed to steam before bottling; and (d) solvent–detergent (SD) treatment, in which the organic solvent tri‐n‐butyl‐phosphate and the detergent Tween 80 or Triton X‐100 are added at intermediate processing steps. Currently, the SD method is most commonly used. The pasteurization and vapor heating methods result in substantial loss of factor VIII activity [99, 100].

Table 5.10 Plasma‐derivative products.

Source: From information provided by the Plasma Protein Therapeutics Association; and modified from Burnouf T. Transfus Med Rev 2007; 21(2):101–117.

Each of these methods uses a different strategy of viral inactivation. There are differing amounts of data about the effectiveness of these viral inactivation methods, because not all of their products have been subjected to randomized controlled trials. In general, it appears that the methods are effective in inactivating virus with a lipid envelope, but infections with nonlipid envelope viruses, such as parvovirus B19 [101] and hepatitis A [102], have been reported.

The first recombinant‐produced coagulation factor VIII concentrates became available in late 1992 and 1993 [103, 104]. It appears that these products transmit no diseases. The factor VIII is produced in murine cell lines, and both fetal calf serum and murine monoclonal antibodies are used in the production process. The products are subjected to viral inactivation steps, even though there should be no way that human viruses should contaminate the products. Although factor VIII is a very antigenic protein, it does not appear that recombinant factor VIII is more likely than plasma‐derived factor VIII to cause development of factor VIII inhibitors.

Coagulation factor VIII concentrates produced by recombinant DNA techniques are more expensive than those produced from plasma [105]. Despite this, the high‐purity (high‐cost) plasma‐derived and recombinant products are the most widely used.

Factor IX concentrates are also free of transmission of most viruses since 1991. Factor IX concentrates vary in purity, and most contain additional coagulation factor [106]. The less pure concentrates contain other coagulation factors and cause some degree of hypercoagulability [107]. Activated factor VII, fibrinogen, prothrombin complex concentrates, von Willebrand factor concentrate, and fibrin sealant are discussed in Chapter 10.

A virally inactivated fibrinogen concentrate prepared from human plasma is now available commercially and is approved by the FDA for the treatment of acute bleeding episodes in patients with congenital fibrinogen deficiency [108–110]. The concentrate is recommended for use in situations when the fibrinogen level is less than 100 mg/dL. Although fibrinogen concentrate is approved only for use in congenital fibrin deficiency [109], small studies of its use in patients with low fibrinogen levels and massive bleeding from obstetric complications, cardiovascular surgery, intra‐abdominal surgery, trauma [108], and an aortic ascending aorta replacement [110] have demonstrated substantially reduced bleeding, and these situations have become its major use [111].

Immune serum globulin (Ig or gamma globulin) prepared by the traditional plasma fractionation technique has been very effective in preventing bacterial infections in patients with agammaglobulinemia and in preventing certain viral infections in immunologically normal persons. Immune globulin is administered intramuscularly because it contains aggregated or oligomeric molecules of Ig, which, when injected intravenously, activate complement, resulting in severe reactions [112]. The limitations of intramuscular Ig are dose, painful injections because of the volume required, and difficulty maintaining plasma levels of IgG. To overcome these issues, immune globulin suitable for intravenous administration is prepared from the plasma of normal donors and thus can be expected to have an antibody content reflective of normal healthy individuals in a large population. There are some differences among different products in the IgA content, the relative proportions of IgG subclasses, and in vitro activity against some viruses. The differences in IgA content are clinically important, because brands that contain much IgA may cause a reaction if given to an IgA‐deficient patient with anti‐IgA. The importance of the other differences among the brands has not been established. The intravenous half‐life of the intravenous immunoglobulin (IVIG) is 21–25 days, which is similar to native IgG.

All IVIG products that are approved by the FDA are labeled for treatment of individuals with impaired humoral immunity, specifically for primary (congenital) immune deficiency. Individual products are additionally labeled for use in (idiopathic) autoimmune thrombocytopenia, chronic inflammatory demyelinating polyneuropathy, Kawasaki syndrome, HIV infection during childhood, bone marrow transplant, and B‐cell chronic lymphocytic leukemia [113–115]. The availability of IVIG makes it possible to maintain the serum IgG level near normal in immunodeficient patients. The amount required varies with the size of the patient and the indication. Usually 100–200 mg/kg per month is used as a starting dosage for patients with primary immunodeficiencies.

Administration of IVIG in autoimmune situations may seem odd. The mechanism of action is thought to be macrophage Fc receptor blockage by immune complexes formed between the IVIG and native antibodies. IVIG is effective for patients with autoimmune thrombocytopenia. Specific IV anti‐Rh(D) is used in Rh‐positive patients with autoimmune thrombocytopenia [113, 116]. This is thought to cause immune complexes with anti‐Rh and the patient’s Rh‐positive red cells, resulting in Fc receptor blockade. Larger doses are usually used for patients with autoimmune thrombocytopenic purpura compared with immune deficiency. IVIG is now used in other immune deficiency or autoimmune states (see Chapter 10).

Adverse reactions to IVIG occur with 2–10% of injections [113]. These are local, such as erythema, pain, phlebitis, or eczema. Systemic symptoms include fever, chills, myalgias, back pain, nausea, and vomiting. Some reactions in some patients are dose related and can be reduced or eliminated by slowing the rate of infusion. The nature and frequency of adverse reactions may differ among the different products, but this is not clear and is beyond the scope of this chapter.

Because IVIG is made from large pools of human plasma, it contains a variety of antibodies, including those against blood groups and possibly anti‐HBs, anti‐HBc, anti‐cytomegalovirus, and so on [113]. Donor screening should eliminate some of these (i.e., anti‐HIV), but patients may have transiently positive tests for certain antibodies, especially ABO, that are passively acquired from the IVIG [117], and some patients may develop a positive direct antiglobulin test. Transient hemolysis has been reported in patients with autoimmune thrombocytopenic purpura and others being treated with IVIG (see Chapter 16). Thus, although hemolysis is unusual, a large proportion of patients receiving IVIG will develop circulating or cell‐bound blood group antibodies. This should be considered if unexplained hemolysis occurs in patients being treated with IVIG.

The approach to blood safety during the past 40 years has been very successful but is nearing the end of its effectiveness [118–121]. Addition of new tests and/or screening measures erodes the donor base unnecessarily and is reactive, allowing patients to be harmed before preventive steps are implemented. Several pathogen‐inactivated plasma products and two pathogen‐inactivated platelet products are widely used outside the United States, and one platelet and two plasma products are FDA licensed for domestic use. This technology is reviewed extensively by Prowse [121, 122] and in a Cochrane review [123]. Refer to Chapter 14 for additional information on Pathogen‐reduced blood products.

Treatment of fresh plasma with a combination of solvent tri‐n‐butyl‐phosphate and the detergent Triton X‐100 inactivates lipid envelope viruses while retaining most coagulation factor activity. The process must be done on a large scale, and plasma from about 2,500 donors is pooled for the SD process. The product has little, if any, risk for transmitting lipid envelope viruses, such as HIV, hepatitis C virus, and hepatitis B virus, but can transmit nonlipid envelope viruses such as parvovirus [124]. Reports of thrombosis in patients with thrombotic thrombocytopenic purpura who are undergoing plasma exchange with SD plasma [125] and deaths in patients receiving SD plasma while undergoing liver transplantation led to withdrawal of an earlier version of that product from the market. It is postulated that these thrombotic complications were due to decreased protein S and plasmin inhibitor activity in SD plasma [125]. A different SD plasma, Octaplas (Octapharma, Vienna, Austria) (Table 5.11), has higher, although not normal, levels of protein S and plasmin inhibitor [126] and has not been associated with thrombotic events. This form of SD‐treated plasma is in rather wide use in Europe [127, 128] and is now available in the United States.

Three pathogen‐inactivated FFP products are in use in Europe. Methylene blue can be added to plasma, and subsequent exposure to visible light inactivates most viruses and bacteria [129, 130]. The plasma can then be frozen as an FFP product. Three other pathogen inactivation methods are used for both plasma and platelets [118–122]. One uses a psoralen compound and ultraviolet A (UV‐A) light [131], one uses riboflavin and ultraviolet B (UV‐B) light [132], and a third method uses ultraviolet C (UV‐C) light [133]. The psoralen compound followed by UV light results in intercalation into DNA or RNA with cross‐links. Riboflavin damages DNA upon exposure to UV light. Both methods prevent nucleic acid replication. Thus, contaminating pathogens are inactivated, but platelets are not damaged. Extensive toxicity, mutagenicity, and pharmacologic studies have given satisfactory results. The psoralen product has satisfactory coagulation factor levels and provides posttransfusion increases in coagulation factors similar to ordinary FFP [131]. The riboflavin‐treated FFP also has satisfactory levels of coagulation factors [132]. Because these products are relatively new, there is little clinical experience reported, but the psoralen product is effective in patients with bleeding due to liver disease [134] and for replacement in patients with thrombotic thrombocytopenic purpura [135]. Plasma treated with the psoralen method is now FDA approved for use in the United States.

Table 5.11 Coagulation factor and inhibitor levels in 12 lots of Octaplas.

Source: Adapted from Solheim BG, Hellstern P. Composition, efficacy, and safety of S/D‐treated plasma. Transfusion 2003; 43:1176–1178.

aPTT, activated partial thromboplastin time; PT, prothrombin time.

^a Data are reported as mean (range).

Three methods used for pathogen inactivation of FFP are also being used to treat platelets [118–121, 136–138]. Initial studies in healthy research subjects and studies in patients with thrombocytopenia indicate satisfactory platelet function for both the psoralen and riboflavin methods [138–140]. Successful clinical trials in Europe using psoralen‐treated platelets prepared by the buffy coat method [141] and in the United States using apheresis platelets [142, 143] have been reported, and those platelets are widely used in Europe [144]. Riboflavin‐treated platelets also appear to be clinically effective [145]. Follow‐up of large numbers of patients do not indicate any unexpected adverse consequences from use of the psoralen‐treated platelets [146].

Two different approaches are under development for inactivation of transfusion‐transmissible pathogens in RBC components. These involve riboflavin [147] and an alkylating agent [148]. The methods involve selective damage to nucleic acid strands, thus inactivating contaminating pathogens while sparing red cells [122]. The methods are effective against most common bacteria, viruses, and protozoa that would be of concern in blood transfusion [122].

Red cells treated with S303 for pathogen inactivation had in vitro properties similar to paired untreated controls for hemolysis, glucose consumption and potassium release, lower lactate levels and pH, and higher ATP, with significant loss of 2,3‐DPG. Thus, in vitro studies of S303 red cells are essentially not significantly different from untreated red cells [148–151].

A clinical trial in cardiovascular surgery was successful, except that two patients developed clinically nonsignificant antibodies to the treated red cells [152]. That method has been revised, and the clinical trial of the revised method in chronically transfused patients with thalassemia reported no difference in efficacy and safety between the control and study groups [153, 154]. The riboflavin method also results in satisfactory red cells [155], and a clinical trial of that WB product prevented transfusion‐transmitted malaria [156].

Inactivation of viruses and bacteria in cellular components, a strategy almost unthinkable a decade ago, is also showing exciting promise with a platelet and two plasma products now FDA approved in the United States. If a WB/red cell technology becomes available, there will certainly be a major impact on the blood supply system and the nature of blood centers producing these components. See Chapter 16 for more details on pathogen inactivation technology.

Two approaches have been attempted to convert A or B red cells to type O. If such a process became practical and widely adopted, it could have a huge impact on blood banking by eliminating most inventory management issues and making more blood available by eliminating outdating of type A and B units. Development of these technologies has been difficult, and neither is near clinical use.

Enzymes can cleave the sugars that confer A and B specificities [157, 158]. The enzymes for this cleavage have been cloned and are available on a scale sufficient to allow for the production of clinical doses of red cells from which the A and B antigens have been removed. Most of the experience involves successful conversion of group B to group O [157]. Although A‐to‐O conversion is possible, some A determinants remained on the carbohydrate, and this work was halted. Clinical trials of enzymatically converted B type RBCs on healthy volunteers reported no signs of hemolysis [157].

A different approach to altering the RBC membrane to convert group A or B red cells into group O red cells is to mask the antigens to produce “stealth” red cells. Polyethylene glycol has been used to covalently bond to red cells to mask blood group antigens, such as ABO, Rh, Kell, and Kidd [159]. Small studies in animals suggest that there is little in vitro damage to the red cells and that they have a normal survival, although such studies have not yet been carried out in humans. It is not clear whether development of this process will continue.

The functions of blood can be grouped generally as maintenance of intravascular volume, delivery of oxygen to tissues, provision of coagulation factors, provision of some defense mechanisms, and transportation of metabolic waste products. Considerable effort has been made to develop blood substitutes or artificial blood, but these products deal only with the oxygen‐delivery function. Thus, more appropriate terms are hemoglobin or red cell substitutes [160].

The ideal acellular red cell substitute would not require crossmatching or blood typing, could be stored preferably at room temperature for a long period, would have a reasonable intravascular life span and thereafter be excreted promptly, and would be free of toxicity or disease transmission. Two approaches have been used: perfluorocarbons, compounds in which oxygen is highly soluble, and free hemoglobin solutions using either human or animal hemoglobin [161]. Hemoglobin chemically binds oxygen, whereas perfluorocarbons have a carbon backbone with fluorine substitutions that have solubility for oxygen 20 times greater than water. The physiologic benefit of this high solubility for oxygen has been demonstrated dramatically by the survival of mice completely immersed in a solution of well‐oxygenated perfluorocarbons.

Hemoglobin can be prepared in solution by lysis of red cells. If the remaining cell stroma is removed, the stroma‐free hemoglobin is nonantigenic. However, stroma‐free hemoglobin in solution has a short intravascular life span and has a low P₅₀ (the point at which 50% is saturated). Thus, research has focused on modifying the structure of the hemoglobin molecule (cross‐linking or polymerization) or binding hemoglobin to other molecules to overcome these two problems [161]. Outdated human red cells, bovine hemoglobulin, and recombinant DNA‐produced hemoglobin have been used as sources of hemoglobin. The potential difficulties with hemoglobin‐based oxygen carriers are rapid clearance of the hemoglobin, hypertensive effects, change in the oxygen dissociation curve, hemoglobin metabolites, immunogenicity, and bacterial sepsis [161].

Five products are or have undergone clinical trials: Polyheme (Northfield Laboratories, Evanston, IL, USA), HemAssist (Baxter Healthcare Corporation, Round Lake, IL, USA), Hemopure (Biopure Corporation, Cambridge, MA, USA), Hemolink (Hemosol, Mississauga, ON, Canada), and Sanguinate (Prolong Pharmaceuticals, LLC, South Plainfield, NJ, USA) [162, 163].

Development of HemAssist has been discontinued after randomized trials demonstrated safety problems [164, 165]. Hemopure was used successfully in a patient with severe autoimmune hemolytic anemia [166] and in a patient with sickle cell disease with acute chest syndrome who refused blood transfusion [167]. However, clinical trials of these products have come to a stop [168, 169]. Currently, the FDA has approved expanded access study for Hemopure (compassionate use) for patients with life‐threatening anemia when a transfusion is not an option [170, 171].

In a careful study, 8 patients with severe anemia (hemoglobin levels of 1.2–4.5 g/dL) who refused a blood transfusion received the perfluorocarbon product and were compared with 15 patients who did not [172]. The amount of oxygen delivered by the perfluorocarbon was not clinically significant, and the patients did not benefit. The major observation in this study was the ability of all the patients to tolerate remarkably low hemoglobin levels and the lack of the need for increased arterial oxygen content in the 15 control patients who had hemoglobin levels of approximately 7 g/dL. Fluosol products are not available, nor are they undergoing clinical trial.

If a hemoglobin‐based oxygen carrier was developed, it is not likely that it will replace most red cell transfusions. The substitutes might be used for immediate restoration of oxygen delivery, such as in trauma or in other urgent situations involving massive blood loss where red cells are not available quickly, but the short intravascular half‐life of these substitutes makes them impractical for long‐term red cell replacement (for instance, in patients with chronic anemia). Because blood typing and crossmatching would not be necessary, the substitutes might be carried in emergency vehicles, stocked in emergency departments, or used by the military or civilians in situations where access to blood is limited. Other potential uses of hemoglobin substitutes include organ perfusion and preservation prior to transplantation and improving oxygen delivery to tissues that have an impaired blood supply. Unfortunately, it does not appear that a hemoglobin‐based blood substitute [24] will be available soon, and the long‐awaited “blood substitute” is not close to reality.

Thomas Gniadek MD, PhD

Although collected whole blood can be separated into its component parts (e.g., plasma, platelets, and packed red blood cells [RBCs]), the amount of each component collected from a single donor is limited in this approach by the amount of whole blood that can be collected at one time. As the demand for blood components increased during the 1900s, especially in the field of oncology, much effort was devoted to developing methods to collect individual blood components from a donor, while minimizing their overall whole blood loss. These procedures were called apheresis, meaning “to take away.”

As early as 1914, Abel et al. [1] removed whole blood, retained the plasma, and returned the red cells to the donor, a procedure termed plasmapheresis. During the 1950s and 1960s, manual apheresis procedures were developed using combinations of the plastic bags and tubing sets developed for whole blood collection. A standard unit of blood was removed, the desired component (either plasma or platelets) separated, and the remainder of the blood returned to the donor; the process was repeated several times, producing a larger amount of the desired component than would have been obtained from one unit of whole blood [2]. The method was time consuming, cumbersome, and expensive; therefore, more automated methods were sought.

Semiautomated apheresis methods were developed generally by two separate research groups [3]. In Boston, the centrifuge apparatus developed for plasma fractionation by Edwin Cohn was modified to process whole blood from normal donors [4], and at the National Institutes of Health a blood cell separator was developed to aid in the treatment of leukemia [5]. Both of these approaches ultimately led to the sophisticated apheresis machines, sometimes called blood cell separators, in widespread use today.

During apheresis, a donor’s whole blood is anticoagulated as it is passes through the instrument where it is separated into components, typically red cells, plasma, and a leukocyte–platelet fraction. The desired fraction or component is removed, and the remainder of the blood is recombined and returned to the donor. Several liters of donor blood can be processed through the instrument, resulting in a larger amount of the desired component than could be collected from one unit (500 mL) of whole blood.

Several instruments are currently available for the collection of platelets, granulocytes,lymphocytes, red cells, peripheral blood stem cells (PBSCs), or plasma by apheresis (Table 6.1). Most of these instruments use centrifugation to separate blood components, some operate in a continuous flow and others with intermittent flow, some require two venipunctures (an outflow and return) and others only one venipuncture. The instruments are operated by microprocessors that control the various parameters, including blood flow rate, amount of the anticoagulant added to the whole blood entering the system, centrifuge conditions, among others. For many years, blood cell separators were designed to collect one component (usually platelets) at a time. Recently, the approach has changed so that instruments can collect several different components either one at a time or in various combinations (Table 6.1). This creates marvelous opportunities for more creative and efficient use of blood donations.

The special centrifuge system developed by Edwin Cohn (a professor of biochemistry at Harvard who originated the plasma fractionation procedure) was modified for use as a blood processor in collaboration with the Arthur D. Little Corporation (ADL) and one of its engineers, Allan Latham, and later James Tullis, MD, a Harvard hematologist [6]. The original motivation to modify the Cohn ADL bowl was for washing and deglycerolizing previously frozen red cells. However, because of the difficulty in obtaining an adequate supply of platelets, it soon became apparent that the Latham bowl could be used to separate whole blood and collect platelets [7, 8]. Soon a free‐standing device, the Model 10, containing the centrifuge bowl, was produced by Abbott Laboratories, but they did not choose to go into the business of manufacturing medical devices.

The Cohn ADL bowl was cumbersome because the bowl itself was made of stainless steel and had many parts, all of which had to be cleaned and sterilized between uses, making it impractical for routine or large‐scale use. The centrifuge bowl system was later made from Lucite and adapted to a special centrifuge [9] that became the Haemonetics system, known as the Model 30. This system was sterile, more self‐contained, and included anticoagulant solutions, storage bags, and ancillary materials. Experience with this disposable plateletpheresis system was gained rapidly in many centers, and it became clear that a large number of platelets could be collected safely from volunteer donors [10–12].

In the early 1960s, an IBM engineer named Mr. George Judson had a child who was treated at the National Cancer Institute (NCI) by leukodepletion. This personal connection led to a collaboration between NCI investigators and IBM to develop a more efficient leukocyte removal instrument [13, 14]. Supposedly, the first blood cell separator was constructed primarily of material obtained at a Bethesda, Maryland, hardware store [15]. Because the instrument was developed at the NCI, the plans were in the public domain. The American Instrument Company obtained these plans and developed their version of the device, which they called the Aminco Celltrifuge.

During leukapheresis with these instruments, the donor would undergo venipuncture in each arm. Blood was pumped out of one vein and through the blood cell separator, where the granulocytes were removed, and the remaining blood was returned to the other arm. Blood flowed to the bottom of the centrifuge bowl by a central channel, flowed outward along the bottom, and up the sides, where the red cells were packed against the walls. Blood separation occurred in a polycarbonate bowl with a clear plastic cover through which the operator could view the separation of plasma, buffy coat, and platelets. Each of these components was drawn off by a separate peristaltic flow pump adjusted by the operator to maintain optimum cell separation. Although the instrument was designed for granulocyte collection, it was also suitable for platelet collection [16].

Table 6.1 Instruments available in the United States for collection of blood components by apheresis.

Source: Data are from information provided by the manufacturers and Burgstaler EA. Blood component collection by apheresis. J Clin Apher 2006; 21:142–151. © 2006, John Wiley & Sons. Reproduced with permission of John Wiley & Sons.

MNC, mononuclear cell; PBSC, peripheral blood stem cell; RBC, red blood cell.

The key to the instrument was the rotating seal, one section of which was attached to the rotating centrifuge bowl and the other fixed to the blood inflow and outflow lines [17]. The NCI‐IBM Blood Cell Separator contained a blood reservoir so that the donor could be bled intermittently but blood flow into the centrifuge was continuous. The Aminco Celltrifuge was a simpler instrument without the reservoir system, but this necessitated continuous bleeding of the donor. These systems, like the original Latham bowl for plateletpheresis, were very cumbersome because they were made of multiple reusable parts that had to be cleaned, sterilized, and reassembled between procedures. To simplify the procedure and to use more disposable equipment, IBM developed the Model 2997 blood cell separator. In this instrument, the centrifuge bowl was replaced with a disposable hollow plastic blood separation channel attached at both ends to the input and output blood flow ports to form a closed loop [18]. This instrument then formed the basis for the IBM, and later COBE (now Terumo), plateletpheresis instruments.

As the Latham bowl and the Haemonetics system were being developed for plateletpheresis, attempts were made to also use this for granulocyte collection. The intermittent‐flow centrifuge was operated in much the same way as for plateletpheresis, but the operator adjusted the blood flow rates and time of component collection to remove the buffy coat rather than the platelet layer [19–21].

Subsequently a new generation of apheresis instrument technology was developed [22, 23], including a microprocessor to control the operation of the instrument combined with a system that lacked the rotating seal present on the IBM, Celltrifuge, and Haemonetics devices. This system, the Baxter CS‐3000, made possible different types of blood separation because different unique separation chambers were developed for the particular component desired [22, 23]. This system had the additional advantage of being completely closed and enabling sterile collection, and thus storage of products for longer than the 24‐hour limitation.

These three basic instruments—the Haemonetics models, the Gambro (COBE/Terumo) blood cell separator models, and the Baxter CS‐3000—were the mainstay of apheresis for blood component production in the United States for many years, each with certain strengths [24, 25]. Recently, newer apheresis instruments have been developed that allow more convenient collection of different combinations of red cells, plasma, or platelets. The principle of each instrument will be described briefly.

Pertinent comments about collection of each component are given next. For details of the operation of the instrument and collection procedure, the manufacturer’s instructions and the references should be consulted.

The Amicus Separator operates using a separation chamber and a separate component collection chamber (Figure 6.1). The centrifuge chamber design contributes to the fluid dynamics and component separation efficiency. Platelet‐rich plasma is continuously elutriated from the separation chamber, followed by further separation into plasma and platelets in the collection chamber. The Amicus Separator can be used to collect platelets [26–28], PBSCs [29], or a combination of red cells, platelets, and plasma [30]. It can also be used to perform therapeutic apheresis procedures, such as therapeutic plasma exchange, RBC exchange, and photopheresis. In plateletpheresis, the Amicus Separator produces about 3.5 × 10¹¹ platelets in 43 minutes [31]. For collection of PBSCs from patient‐donors stimulated by chemotherapy and granulocyte colony‐stimulating factor (G‐CSF), approximately 1.3 × 10¹⁰ mononuclear cells (MNCs) and 1.4 × 10⁸ CD34+ cells can be obtained from an 8‐L blood processing procedure [32]. When concurrent red cells, platelets, and plasma are collected, the procedure produces 198 mL of red cells, 3.9 × 10¹¹ platelets, and 198 mL of plasma in 74 minutes [30]. The red cells can be stored the usual 42 days when they are resuspended in the additive solution AS‐1 (Adsol).

This multiple‐component collection system uses continuous separation with fluid flows controlled by a pneumatic pump system and internal sensors to monitor the weight of blood, fluids, and collection components [31, 33, 34]. The plastic, disposable, rigid‐wall separation chamber and cassette interfaces with the pneumatic pump to control fluid flows. A leukodepletion filter is part of the system, and the instrument automatically adds the red cell preservative. Although separation is continuous, blood flow from the donor is intermittent, with plasma being returned after withdrawal of about 300 mL of whole blood. The Alyx can produce two units of red cells in about 35 minutes [31] or up to four units of plasma in less than 45 minutes. The Alyx can also produce combinations of components, for example, one unit of red cells with up to three units of plasma.

The Trima Accel can be used for collection of platelets, plasma, or red cells in various combinations [27, 35–39] with a single‐needle technique. The Trima Accel takes about 51 minutes to produce 3.5 × 10¹¹ platelets [27]. Platelets are leukoreduced using an in‐line chamber during the collection procedure. Red cells, platelets, and plasma collected using the Trima Accel have satisfactory in vitro characteristics, in vivo survivals, and in vivo clinical effectiveness [35–40].

The Haemonetics system uses a disposable, transparent Lucite centrifuge bowl for blood separation [9]. After venipuncture is performed and the donor is connected to the instrument, the operator activates the instrument and blood is pumped from the donor into the centrifuge bowl (Figure 6.2). Anticoagulant–citrate–dextrose anticoagulant is added to the blood as it leaves the donor. The centrifuge bowl spins at approximately 4,800 rpm and continuously separates the blood as it enters the bowl. When the volume of blood removed from the donor exceeds the capacity of the bowl, plasma begins to exit the bowl and is collected in a bag. The platelet/buffy coat layer accumulates at the top of the red cells, and as the bowl continues to fill, this layer moves toward the exit port. When the platelets—visible as a white band between the red cells and plasma—reach the exit port, a valve is activated, diverting the flow pathway into a separate bag, where the platelets are collected. When the platelets have been collected, the blood flow is stopped, the pumps reversed, and the plasma and red cells recombined and returned to the donor. This cycle of filling the centrifuge bowl is repeated several times to obtain the desired platelet yield.