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Chapter 4

Insulin Errors in the Inpatient Setting

Richard Hellman, MD, FACP, FACE¹

¹Clinical Professor of Medicine, University of Missouri-Kansas City School of Medicine; Medical Director, Heart of America Diabetes Research Foundation, North Kansas City, MO. DOI: 10.2337/9781580406086.04

DOI: 10.2337/9781580406086.04

Introduction

Insulin therapy is the best and most powerful tool at our disposal for the control of glucose levels in the inpatient setting, but errors in providing this crucial therapy not only diminish the effectiveness of this therapy, but also, in some cases, cause in-hospital morbidity and even mortality. It is for this reason that the Joint Commission on Hospital Accreditations (JCOHA) considers insulin one of the five “high-alert” medicines that are most commonly associated with serious injury or death.¹ Numerous studies have shown that errors in insulin therapy are a frequent cause of excessive morbidity and mortality.² In one study, in the inpatient setting, one-third of the deaths of patients with diabetes resulting from a catastrophic error were due to errors in insulin therapy.³

This chapter offers explanations for why errors in insulin therapy occur, discusses the types of errors, and provides a practical guide to strategies that have been shown to be useful to both reduce the frequency of errors and prevent injuries resulting from errors related to insulin therapy in the inpatient setting.

The chapter looks at the problems from three different, but overlapping, perspectives. The first perspective takes a systemic approach—looking at the dominant role that organizational and systems issues play in the development and continuation of higher rates of errors in insulin therapy. The second perspective follows the individual providers of health care, the physicians and nurses and other key hospital personnel, and pays special attention to a relatively underdiscussed but crucial aspect: diagnostic errors and their role in injurious errors in insulin therapy. The third perspective examines the prevention of specific types of errors, looking at the type of medication errors in insulin therapy described in a recent publication by the American Society of Health-System Pharmacists (ASHP).⁴ The chapter concludes with a list of proposals to reduce the frequency of errors in insulin therapy and to reduce risk of any morbidity and mortality from such errors.

Background

Despite overwhelming evidence of the need to reduce significant hyperglycemia and avoid hypoglycemia during the routine use of insulin in hospitals,^5,6 glycemic control remains suboptimal in many inpatient settings. In some cases, as a result of errors in insulin therapy, glycemic control deteriorates during a hospital stay. For example, in 2007, the Centers for Medicare and Medicaid Services (CMS) reported data on so-called never events related to glycemic control, that is, disorders of glycemic control that should never have their onset in a hospital. They identified three such events: hospital-acquired diabetic ketoacidosis (DKA), hyperosmolar hyperglycemic syndrome (HHS), and severe hypoglycemia. They reported that during a one-year period there were 15,848 documented such events. Of these, 72.4% were episodes of DKA that began during an inpatient stay, 20.5% were significant cases of HHS, and 7.1% were cases of severe hypoglycemia resulting in coma. In 2008, CMS announced it would not pay for hospital stays in which those never events occurred. Yet, some data from several states show that these never events in glycemic management are still occurring in U.S. hospitals at a rate of close to half of the 2007 rates.⁷

Few experts in hospital medicine were surprised that the threat of nonpayment by CMS did not have a greater effect on reducing the frequency of these so-called never events. Hospitals are extraordinarily complex structures, and the complexity of care needed for patients who need improvement of their glycemic control often stresses the systems of care present in the hospitals and reveals their shortcomings.⁸ Changes in the present hospital systems of care will be needed if we are to make in-hospital care safe for the patient with diabetes.

Systemic Issues in the Development of Errors in Insulin Therapy

To understand why some of the errors occur so often and why it is so hard to prevent them, it is important to look at systemic issues that play an important role in the development and persistence of errors in insulin therapy over time. It may seem counterintuitive, but some decisions made far from the bedside, often termed the “blunt end of care,” have a profound effect on the chance that errors will occur. The shortage of nursing personnel is one such example. Errors involving nurses at the point of care, also termed the “sharp end of care,”⁹ are more likely to occur when shortages in nurses result in the individual nurse being overworked,¹⁰ and spending too little time focusing on the many crucial tasks involved in accurate use of insulin therapy. These include (1) assessing whether the order for insulin is reasonable and appropriate for the patient at that point in time; (2) checking to ensure that the appropriate insulin dose of the correct type of insulin is administered to the right patient by the right route at the right time; and (3) verifying that the patient’s blood glucose and clinical status are being monitored sufficiently so the effect of the insulin can be measured and, if needed, the therapy can be altered. The support staff responsible for glucose monitoring also need to have an appropriate workload and training to provide reliable and timely glucose testing. In addition, it is important for all care providers to listen to the patient’s perspective and to use that information to ensure that the care being given is patient centered, effective, efficient, equitable, timely, and safe.

Electronic Health Records

Many hospitals are moving from the traditional paper-based hospital charts to fully operative electronic health records (EHR). This key system change has many benefits, including the ability to share information more rapidly and widely among members of the health-care teams.¹¹ As a systems tool, EHRs have great potential. The clarity and lack of ambiguity of data sources, particularly physician and nursing notes and orders, reduces the chance for medical errors.¹² If properly designed, the EHR can provide decision support and forcing functions that may reduce certain types of errors of insulin therapy. But flaws in any electronic record can introduce other errors—for example, if the screen routinely accessed by the providers does not contain crucial information needed at the time they are ordering insulin therapy, or when the decision support tools are judged to be unhelpful or burdensome and, as a result, are routinely bypassed by the user of the EHR.

Computerized Physician Order Entry (CPOE) systems are extremely important¹² and have great value in the care of the patient with diabetes, particularly when the algorithms used for specific insulin orders can be reduced to a validated, evidence-based order set and provided to the user of the CPOE system. Examples of these widely used types of order sets are shown in Table 4.1.

Table 4.1—Examples of Order Sets Widely Used in CPOE Systems

• Intravenous (IV) insulin infusion

• Subcutaneous (SQ) basal-bolus insulin

• Hypoglycemia recognition and treatment

• Treatment of diabetic ketoacidosis

• Treatment of hyperosmolar hyperglycemic syndromes

• Discharge insulin therapy

• Transition from IV to SQ insulin therapy

• Insulin therapy for patients on IV hyperalimentation

• Insulin therapy for patients on high-dose corticosteroids

• Insulin when there is an interruption of nutritional therapy (IV or oral)

• Consideration of patient self-use of SQ insulin pumps in the hospital setting

• Criteria for continuing or discontinuing patient self-use of their insulin pumps.

The more often a validated and complete set of tasks can be put into an order set that is available to the physician and hospital staff, preferably in a CPOE set but alternatively in a paper-based order set, the easier it is to administer therapy with fewer errors, to monitor the quality of the work that has been done, and to identify opportunities for improvement. It would be a mistake to believe that a set of often-complex orders for insulin therapy will improve care by itself. The process of introducing it and teaching health-care providers and staff how and when it should be used is key. Subsequent proficiency testing is central to the success of any new CPOE, particularly in the case of insulin therapy, in which the effects of a momentary slip or omission in an order sequence can result in harm to the patient.

Culture of Safety

Many experts in the area of patient safety believe that sponsoring a culture of safety is important for nearly any institution involved in patient care, and mandatory for a high-alert therapy, such as insulin therapy. A culture of safety is created when a collection of individuals decide that they will work together in a collaborative way to eliminate injurious errors and to promote patient safety.⁸ A culture of safety in hospitals is much more effective when the hospital leadership is strongly supportive. The group engaged in the culture of safety should develop a nonhierarchical approach, which includes checking not only their own work, but also that of others. Back-up checks should be routine. The entire group must focus on and measure their performance and use nonpunitive methods to improve performance. A successful team strives to work in collaboration and to develop a sense of both collective and individual mindfulness.¹³ Organizations that adopt such a philosophy are typically ones that value education and quality improvement, including constant measurement of relevant metrics, examination of their own performance, and continued collaboration to reduce the errors in care.^4,14–16 Human error is part of the human condition and is to be expected, but injury to patients can and should be prevented.

Both the patient and their family as well as other key supportive figures should be included in the culture of safety. In the inpatient setting, an engaged patient and family can be an important set of observers of the patient’s clinical status, and a highly motivated group of helpers to prevent errors in insulin therapy.

Education

Education is often overshadowed by the acute medical need and not a priority in the inpatient setting. From a systems perspective, however, education is an important tool in the prevention of insulin errors.^17,18 For example, recent data show that the faculty caring for patients in academic centers may not be up to speed when queried about their knowledge of basic principles of modern management of insulin in the inpatient setting.^19,20 Several organizations have developed excellent tools to educate health-care providers and patient care teams involved in the care of patients with diabetes regarding necessary information to deliver appropriate insulin therapy, reduce insulin errors, and provide quality care.

There is a misconception that the most important aspect of education is the content of the education. Although content is crucial, data suggest that attention to the preferred style of learning of the health-care providers can greatly increase retention and understanding of the insulin safety principles.²¹ Flexibility of the education style and format may pay great dividends in patient education as well.

The education should be first targeted at the areas of highest frequency of errors, such as choosing the appropriate types, dosing, and route of insulin therapy; administering the insulin safely and accurately; and timely and accurate monitoring of the glucose levels. Other targets should include the development of the health-care provider’s understanding of how insulin therapy affects the patient’s clinical outcomes and how the clinical status of the patient in turn affects the decisions for their insulin therapy.

Scope of Education of Hospital Staff

All staff involved in the care of the patient with diabetes require education and training in the tasks needed to safely use insulin therapy. Too often, the as-needed (or per diem nurse, PRN) nursing staff and the evening or night shifts receive little training and education. A common cause of inpatient hypoglycemia is when insulin is given before a meal, but the patient is then transported to another part of the hospital and unable to eat the planned meal, resulting in hypoglycemia. Ideally, the hospital will have a comprehensive, in-depth resource and training available for the entire hospital staff, but this is a labor-intensive project, which so far has been done by only a few.^16,22 The use of diabetes teams throughout the hospital is a useful tool,^15,16 as is the development of preferred areas for more complex glycemic control. The use of online resources, especially for education modules or for reference, is also useful.

Glucose Monitoring

In the hospital setting, glucose monitoring is sometimes done by the central hospital laboratory, but the majority of the glucose monitoring is done with the use of point-of-care (POC) glucose monitors. A few centers are using POC blood-gas analyzers to measure glucose in critical care units, and a small but slowly growing number of centers are using continuous glucose monitoring systems (CGMS) in specific settings.^23–25 At present, most inpatient centers rely heavily on POC glucose monitors for the vast majority of their glucose measurements, in large part because of the ease of use and timeliness. It should be remembered, however, that the central hospital laboratory method is highly accurate and relatively free of interfering substances, and should always be used when a POC glucose level needs confirmation or when the accuracy of the POC meter is in question.

From a systems perspective (see Figure 4.1), several key aspects of POC glucose monitoring should be evaluated constantly:

1. The choice of a POC glucose monitoring system;

2. The frequency of validation of the glucose strips and the monitors;

3. The robustness of the staff education programs and proficiency testing; and

4. The degree to which glucometrics are used to improve in-hospital glycemic control and to reduce errors in insulin therapy.

Figure 4.1—Systems perspective for medical errors.

These systemic issues are key because a significantly inaccurate glucose level may lead to relatively large insulin dosing errors. Additionally, the vulnerability of the particular POC glucose meter may make it unsafe in selected circumstances, and no POC glucose meter should be used without a clear understanding of its limitations and when it is unsafe to use that meter to monitor glucose levels.

Glucose Monitoring Errors

When insulin is to be administered, the glucose level at that time point is important data needed to select the correct dose and the optimal route of administration, and an important safety check to avoid iatrogenic hypoglycemia. Other factors that should be considered to avoid hypoglycemia include the clinical context of the patient and the factors that can be expected to influence insulin resistance of the patient and the expected effect of the dose of insulin. The patient’s vulnerability to hypoglycemia also needs to be considered. For example, an 80-year-old patient with chronic renal failure and hypoglycemic unawareness will be extremely vulnerable to fasting hypoglycemia.²⁶ This patient requires careful and conservative insulin dosing and frequent glucose monitoring. To do otherwise would be an error. Likewise, if a patient receives intravenous (IV) insulin, but the frequency of glucose monitoring is every 6 h, the infrequent monitoring is an error, because the change in glucose levels after IV insulin can be rapid. In this case, the probability of harm increases greatly when the glucose measurements are too far apart.

Often the health-care team uncritically assumes that the monitoring method is accurate. In 2009, the U.S. Food and Drug Administration (FDA) reported the death of 13 patients with diabetes on peritoneal dialysis who were being monitored with a widely used glucose meter that followed a glucose dehydrogenase method, using a pyrrolo-quinoline quinone (PQQ) coenzyme to measure glucose concentrations. This method is less sensitive to ambient oxygen levels and some other interfering substances and will falsely measure maltose as glucose. Because patients who receive icodextrin in their peritoneal infusate will slowly metabolize the icodextrin to maltose, this process can lead to high maltose levels in the patient’s blood up to 2 weeks after the last peritoneal dialysate. In each of the cases reported by the FDA, the health-care providers used a POC glucose meter of the PQQ type, resulting in an erroneously measured and markedly elevated POC glucose, which was used to order inappropriately large doses of insulin and resulted in severe hypoglycemia, coma, seizures, and ultimately death. Despite the 2009 FDA report, however, a recently published report indicates patients in some hospitals and outpatient centers are still using meters of this type with patients who either are or recently have been on peritoneal dialysis with similar lethal outcomes.

The FDA, in response to strong concerns presented by multiple organizations and individuals, most recently tightened the standards for accuracy of POC glucose meters being used in the hospital setting. The new standards recommended by the FDA are expected to be implemented by the end of 2015, and state that 99% of the glucose values must be within ±10% of the glucose levels ≥70 mg/L and within ±7% of values <70 mg/dL. Also, 100% of the values must be within ±20% of the glucose levels ≥70mg/dL or within ±15% of those values <70mg/L. The latter standard is crucial, as other authors have shown the potential for severe errors in clinical decision making when the result obtained by the POC glucose meter is so far from the true value of glucose so as to be misleading.²⁷

Recently Scott et al.²⁸ pointed out the weaknesses of the POC meters in use, especially in the operating room²⁹ and in intensive care settings. Variations in hematocrit, blood pH, oxygen saturation, fever, dehydration, or ketosis all had varying and sometimes significant effects on the results obtained with a POC glucose meter,³⁰ and in critical care, most POC glucose meters were clearly inferior in accuracy to the results obtained by intra-arterial samples tested for glucose levels on POC blood-gas analyzers. Arterial samples are used in preference to fingerstick glucose samples in patients who have circulatory compromise, and the capillary values of glucose may diverge significantly from the arterial values when acidosis or circulatory collapse alters the capillary blood flow.

Errors in monitoring may be due to sampling errors when the site from which the blood sample is obtained does not accurately represent the true blood glucose value. In the operating room, severe hypoglycemia has resulted when the anesthesiologist did not realize the arterial line that they were sampling from was being flushed with 5% glucose solution.³¹ As a result, insulin was given in error to a hypoglycemic patient. Similar errors can occur when the line from which the specimen is being drawn has “dead space” and that line cannot be flushed adequately, diluting the sample and giving an erroneous result.³¹

Each hospital must be aware of the strengths and the weaknesses of the POC meters used in their institution. POC meters that use a glucose-oxidase method will tend to give falsely elevated glucose values when the patient is hypoxic, and lower glucose levels when high levels of acetaminophen are present. Glucose-dehydrogenase meters will give more accurate levels in the presence of hypoxia, but falsely lower results in the presence of dopamine infusions and falsely higher glucose levels when higher levels of acetaminophen are present.

In addition, the storing and the care of the glucose monitoring strips are crucial. If the bottle containing the strips is left open, the strips may deteriorate rapidly. If the strips are stored at a temperature ≥39.2°C, the strips may give falsely low blood glucose values, and when the strips are stored <20°C, the strips may give falsely high values. Strips also may be destroyed by extremes in temperature or humidity.

Some of the strips hospitals now use do not have good corrections for hematocrit levels. This is particularly crucial in intensive care and operating room suites, where wide variations of hematocrit are common. Falsely elevated glucose levels in POC meters when patients are anemic occur and most meters do not have a specific method to deal with hematocrit variation. Cembrowski, a NICE-SUGAR investigator,³² found that some of the batches of his POC glucose meter strips did not correct for hematocrit variations as claimed by the manufacturer. He concluded that the error due to the faulty strips may have misled his team and caused the diagnosis of hypoglycemia to be either delayed or missed entirely.³²

In addition, proper training of staff on the proper technique of performing POC glucose monitoring is crucial. Too often, POC glucose monitoring is done in hospitals by the most poorly trained and poorly supervised staff. The resultant errors can be quite large. For example, if a person fails to clean the finger properly before obtaining a glucose sample, the result may be as much as 35% or more above the true glucose level, while failure to adequately dry the finger can dilute the sample and give a falsely low value that may be as much as 25% below the true glucose level. Such large deviations from the true blood glucose may cause an outlier that can mislead the prescribing health-care provider.³³

Glucometrics

Evidence-based metrics can be used to evaluate not only the harmful errors but also noninjurious errors and latent errors. A latent error occurs when a deviation from optimal care occurs that, although not directly causing harm, increases the probability that an important error will occur later. Some latent errors include systemic issues that create recurrent vulnerability of the health-care system, such as excessively high patient-to-nurse ratios, a situation in which the nurses have more to do than they can safely perform. Another common example of a latent error is leaving a vial of U-500 amid a number of U-100 vials. This can be reliably expected to increase the risk of vial confusion, potentially resulting in an overdose of insulin. Another example of a latent error that is a systemic error at the so-called blunt end of care is allowing inadequate lighting in an area of the hospital where staff must read labels on vials, syringes, and infusion sets.

Both latent errors and noninjurious errors are important to identify and correct, as these ultimately may lead to patient injury. It is imperative to educate the caregivers and to give them feedback, if we are to reduce the total number of errors. Moreover, because injurious errors usually involve multiple errors, often by multiple caregivers, the chain of undetected errors and the sequence of errors may result in an injurious error. Medicine is a high-risk endeavor and errors are frequent. Although most errors are corrected by the person who made them, multiple errors often include some that escape detection and cause harm. As an example, the development of DKA de novo in a hospital setting, still a far-too-common event, usually involves multiple people and multiple errors of omission and may result in an injurious or even lethal event.

Diagnostic Errors

No discussion of errors in insulin therapy is complete without discussing the role of the individual and the human factor in errors in insulin therapy. Although defective systems may create potential for “error traps” or situations in which different individuals make the same error, the role of the individual at the POC is key to understanding how to prevent injurious errors.

Humans frequently make errors and, when candid, most people will admit that they frequently have slips and lapses that, for the most part, they correct themselves. Not only do people have different cognitive abilities, but most people have two distinct mental processes active at any time, often termed by cognitive psychologists as type 1 and type 2 thinking.³⁴ Type 1 is intuitive, rapid, and almost automatic, relying upon a vast warehouse of experience and knowledge. Many people use this method of thinking much of the time because of its ease and speed. Examples of this type of thinking include what we do when driving a car or when a jazz musician is playing with their fellow musicians. This type of thinking, however, although blindingly fast and intuitive, is still error prone, subject to cognitive biases, and not at all quantitative. Type 2 thinking, by contrast, is slow, deliberative, and analytic. This form of thinking is more likely to be useful in quantitating risk, but may be just as prone to some cognitive biases as type 1 thinking. We would prefer our accountant to use type 2 thinking. But when it comes to the formulation of a medical diagnosis, particularly when the diagnostician feels confident or is working quickly, pattern recognition, which is usually a function of type 1 mental processes, is the predominant pattern. Although the experienced diagnostician may be correct, the pattern of thinking they most often use is particularly prone to overconfidence and a premature closing of the possibility that the diagnosis may either be incorrect or incomplete.

In a seminal study of the causes and frequency of diagnostic errors, Graber et al.³⁵ looked at 100 cases of diagnostic error. These resulted in 90 injuries and 33 deaths. Of the 100 cases, seven were due to no-fault errors alone. Of the remaining 93 cases, many had system-related factors (63%) and cognitive errors. The system-related factors were most often organizational problems (94.3%). Only 5.6% of the system-related factors were the result of technical and equipment problems.

In 74 cases of diagnostic errors resulting from faulty cognition, cognitive factors were noted 320 times (4.3/case). The most common problems were faulty synthesis (82.8%) or faulty data gathering (14.6%). Surprisingly, inadequate knowledge or skill accounted for only 3.4% of the diagnostic errors resulting from faulty cognition. Put another way, it wasn’t common that the errors occurred because of a lack of knowledge, but rather because of how the clinician collected and put together the data to formulate a diagnosis.

Certain cognitive and system-related factors co-occur commonly, such as an inadequate history leading to misinterpretation of lab results. In general, faulty information gathering greatly increased the risk that there would be a faulty synthesis of data and premature closure, as for example, “it can only be this.” Faulty data gathering was identified in 45 instances by Graber et al.,³⁵ but they identified inadequate or faulty knowledge or skills least often, in only 11 cases overall in the study. The researchers also identified failure to consult an expert as a significant cause of diagnostic error (15 cases), as well as failure to periodically review the situation (10 cases) or failure to gather other important information to verify the diagnosis.

Medical diagnostic errors are common when the presentation of the patient is atypical, as for example if a young woman appears in the emergency room with right lower quadrant pain that in actuality is due to undiagnosed DKA and not appendicitis. If therapy for DKA is delayed or even not done, the results may be catastrophic. It is likely that many of the so-called never events noted by CMS were due to diagnostic errors early in the development of DKA, HHS, or severe hypoglycemia.

Another not uncommon example of a diagnostic error that may occur is in the elderly patient with diabetes with HHS. The patient may present with focal signs of limb weakness that mimic a cerebro-vascular accident (CVA), but the real diagnosis is severe HHS, and if care is delayed the risk for mortality is very high.

The routine checking of other providers’ work and conclusions in real-time is crucial in preventing such diagnostic errors. It is always useful for the diagnostician to ask whether there is some other explanation for what they see than the diagnosis they have decided on. It is also useful to provide feedback to all members of the diabetes care team. Often the feedback of relevant data will allow people to revise their initial impression and protect the patient from serious errors in insulin therapy.

It is surprising that rule-based errors are often difficult to correct. The presence of a rule that is easy to use, but incorrect, often generates resistance to change. Probably the best known example is sliding-scale insulin (SSI). It is an example of a simple, clear rule of giving insulin that is “strong, but wrong.” Because of the simplicity of such rules, there is often resistance to discontinue using these, even when people know that the rule does not work well. Ideally, SSI as monotherapy should not be allowed to be part of a computerized insulin order set, and basal-bolus insulin orders promoted as the alternative.

Types of Insulin Errors

In 2013, the ASHP convened a panel of experts to focus on the goal of enhancing the safety of insulin use in hospitals. They began by grouping the types of errors in insulin therapy into six categories: prescribing, transcribing, dispensing, storage, administering, and monitoring. Their nomenclature is a useful place to begin.⁴

Prescribing Errors

These errors are among the most common and the most important. Among the common examples is when the prescriber chooses an incorrect dosage or a method of insulin dosing that is irrational, as for example, SSI as monotherapy. More variables should affect the choice of insulin dosage than just the immediate glucose result. SSI monotherapy is both a rule-based error and also a knowledge-based error, because it indicates both an illogical belief and a lack of understanding of insulin therapy. The evidence shows that it is an inferior method of prescribing insulin at best, and at worst, it has resulted in severe morbidity and even mortality when prescribed to a patient with DKA or HHS.

During insulin prescribing in hospitals, the prescriber needs to provide for both basal and bolus insulin requirements, the bolus doses used to balance nutritional intake, and correction doses when the glucose is outside of the optimal glycemic range. The basal needs may be highly variable, affected by the underlying comorbid conditions and by concurrent medications, which may increase or decrease insulin resistance, or by other mechanisms increasing the risk for hyper- or hypoglycemia. Some examples are shown in Tables 4.2 and 4.3.

Table 4.2—Comorbid Conditions

Increasing hyperglycemia risk	Increasing hypoglycemia risk
Infections	Weight loss
Myocardial infarction	Renal failure
Metabolic acidosis	Advanced age
Severe pain or anxiety	Adrenal insufficiency
Pregnancy	Liver failure
Surgery	Heart failure
Acute asthma	Alcoholism

Table 4.3—Medications

Increasing hyperglycemia risk	Increasing hypoglycemia risk
Corticosteroids	β-blockers
β-agonists	Incretins (when used with insulin, sulfonylureas)
Protease inhibitors	Sulfonylureas
Sirolimus	Haloperidol
L-asparagine	Pentamidine
Atypical antipsychotics	Tramadol

The nutritional needs of the patient need to be coordinated with a coherent plan for insulin therapy, and the prescription for insulin therapy must reflect the current nutritional therapy and route, as well as provide for a change in insulin therapy if nutritional intake is reduced or stopped. Different methods of nutrition require different types of insulin, and sometimes different routes. For example, basal insulin dosing twice daily may be optimal for enteral feedings, but IV insulin is best when oral intake is uncertain and the expected insulin requirements may decrease rapidly. Orders for varying contingencies, such as what to do if oral intake is suddenly interrupted, will reduce errors.

Poor communication between the prescribing and treating health-care providers can result in an error of inadequate insulin dosage. For example, if a pulmonary intensivist adds β-agonists and corticosteroids for the respiratory needs of the patient, but the prescriber of insulin is unaware that the consultant, in effect, has increased the insulin resistance, the prescriber will choose inadequate insulin doses that will result in severe hyperglycemia.

The route of insulin administration is a key consideration. A patient with shock and hypotension or severe dehydration may be highly likely to have delayed and erratic absorption from subcutaneous (SQ) sites. An IV approach for insulin therapy would be much more effective. Alternately, in another scenario, the rapidity of the change in insulin resistance may be so fast that only an IV use of insulin therapy will be able to match the rapidity of the change in insulin needs.

The type of medical record, either paper-based or electronic, may affect the type and frequency of prescription errors. In paper-based hospital records, the errors may occur when prescribers write down what they believe to be the correct insulin type, but instead list an incorrect type of insulin because the insulin they chose had a similar sounding, but incorrect, type (short-acting versus long, or vice-versa). This kind of error is often termed an intentional error. In contrast, an example of a so-called unintentional error is a misspelling or error in the prescriber’s penmanship, which makes the result ambiguous in appearance. The most common error is using a “U” to depict units, which, if not written clearly, may be read as a zero. Another common error is to have a trailing zero after a decimal point, as for example, an IV insulin rate of 1.0 units/h, which, if the decimal point is not easily visible, may be seen as 10 units/h. Other examples of prescribing errors occur when the orders are verbal and may not be clearly understood by the transcriber, who is not familiar with the plan. These common errors can be reduced with the use of evidence-based order sets, preferably in an EHR.

Transcribing Errors

Transcription errors, while much more common when paper charts are used or a verbal order is transcribed, also may occur whenever there is a transition of care and a new set of orders is used. In many hospitals, a reconciliation of medication is done on a transfer from one care unit to another, and a new set of orders for insulin is generated. The person who performs the reconciliation is the one who may cause a transcription error and it is particularly common upon discharge in cases in which new orders are generated for post-hospital care. As an example, in one recent study, 18% of all patients who were discharged after an acute myocardial infarction (MI) did not receive their medications to control blood glucose levels upon discharge.³⁶ Sixty-seven percent of the time, one of the omitted medications was insulin.³⁶ Their retrospective review confirmed that 81% of the time, the omission of the medication for glycemic control upon discharge was the result of medical error. The frequency of readmission postdischarge is directly related to such errors upon discharge. The “hand-offs” in care transitions are among the events at highest risk for errors.

Dispensing Errors

Dispensing insulin can be a complex process and can vary widely from one institution to another. The trend, correctly so, is to have the hospital pharmacy solely responsible for the labeling, storage, and dispensing of the insulin to the nurse who is to administer the dose, whether it be IV or SQ. The pharmacist usually has the responsibility of being sure that the correct insulin dose is in the IV solution that is to be administered, and in the single dose pen or syringe that is to be sent to the floor, but the accuracy of the dispensing process is not guaranteed. As with all aspects of the processes of care, it is helpful to keep metrics on the performance in the pharmacy regarding errors of all types and to provide timely feedback so workflows can be changed to improve performance.

Storage Errors

Storage of insulin is an issue in the hospital setting and can be the source of serious errors. There are many types of these errors. Some hospitals, for example, may use U-500 insulin as well as the standard concentration, U-100 insulin, and may store the U-500 insulin vials in the clinical area, at the nurses’ station, for the convenience of the staff. This error type can be remedied by storing U-500 insulin in the hospital pharmacy and dispensing it only with bar-code labeling that is specific for a patient on the clinical unit. Some insulin pens and vials, however, may be stored on the unit in a secure drawer, for the individual patient. The use of double-checks and bar coding of all insulin-containing pens or vials or syringes is highly recommended to reduce risk of patient injury.

Administering Errors

After prescribing and transcribing errors, the administration of insulin is perhaps the next most frequent type of error, and it is certainly the one that is most visible. Unfortunately, in many hospitals, the important function of administering the dose of insulin is not done without frequent errors. A recent review of insulin therapy error data from the British National Patient Safety Agency showed the high frequency in which patients received a wrong dose, strength, or frequency of insulin.² They also found that insulin doses were commonly omitted or the wrong insulin product was used.

Prefilled insulin IV containers and insulin syringes prepared by the pharmacy may reduce the burden somewhat, but there are many potential sources of error. The nurse needs to double-check to ensure that the ordered insulin dosage is correct. In addition to checking the insulin type, route, and dose, time may have elapsed since the order was given, and understanding whether the order for this dose of insulin is still appropriate for the patient is important. Communication between nurses and physicians is essential to the safety of insulin administration. In many discussions on errors of insulin therapy, the role of the nurse in catching errors or potential errors made by others is overlooked, but in one study, 86% of the errors that were avoided were found by the nurses.³⁷

New technologies may present special challenges as well. Although insulin pens have been widely used in hospital settings, the accuracy of pen delivery depends on the use of proper technique.³⁸ For example, some pens will not deliver the full dose of insulin unless the needle is held in place for 6 sec after administering the dose. If the pen is removed before 6 sec has elapsed, the full dose is not injected into the site. Likewise, although needle guards are designed to prevent needle-stick injuries, when unfamiliar with the type of insulin pen, nurses not infrequently suffer needle-stick injuries despite these guards.

Smart IV pumps are IV infusion pumps designed not to allow infusion errors by prohibiting rates of infusion outside of what the pump memory has programmed to be the limits of safe infusion for that individual drug. They are a technological advance and have been shown to reduce some types of errors, but even these smart pumps may present complexities for the health-care provider unfamiliar with their proper function and errors may result.

Glucose Monitoring Errors

The ASHP recommendations regarding glucose monitoring emphasize the training of those who perform the glucose monitoring and the establishment of minimum frequencies of glucose monitoring: no less than every 4–6 h if a patient is on insulin but as often as hourly with insulin infusions. These recommendations focus on the need to document and communicate the results of glucose monitoring to the clinical team and to provide both critical values on an urgent basis and alerts to notify appropriate caregivers when there is an increased risk for hypoglycemia. The ASHP also emphasizes the need to verify POC glucose values when a critical result is noted. They also recommend the need for observation of the patient if self-monitoring is allowed. These are all sound recommendations.³⁹

Recommendations for Change

Systemic Recommendations

• Establish a culture of safety with specific attention to assuring patient safety throughout insulin therapy. The need for timely and effective communication, coordination, and teamwork is key. The environment should promote a nonpunitive learning environment.

• A multidisciplinary management team should be formed and given authority to manage or comanage critical clinical problems or emergencies in glycemic control. They should have an ability to provide education and consultation for hospital staff, health-care providers, and patients as resources allow, and to advise the hospital administrator on suggested improvements in glycemic control.

• The hospital administrator should seek input from the glucose management team and other relevant people or groups regarding the need for additional staffing or training or other resources relevant to improving diabetes care and reducing errors in insulin administration. The hospital administrator should strongly support a culture of safety at the institution and focus care staff on clinical goals, not on nonclinical goals.

• The ASHP professional practice recommendations for the safe use of insulin in hospitals should be incorporated into the hospital’s policies and procedures. Double checks should be the norm for each of the steps in insulin therapy.

• An EHR with capabilities of CPOE should be instituted hospital-wide and all parts of the hospital should use either the same system or one that communicates transparently with the main EHR. Decision support tools and forcing functions, if carefully validated, may be used to improve safety of insulin therapy.

• Hospital-wide insulin order sets should be made available for each of the clinical situations in which errors in insulin use may occur.

• Processes of care for each step in the provision of insulin therapy, from prescription to administration and monitoring, should be written unambiguously in preprinted, approved, evidence-based orders and should be reviewed at least annually to ensure that they are being used correctly and remain valid.

• The quality of POC glucose monitoring should be a high priority. The POC glucose meter performance should be tested at regular intervals under the direction of the hospital clinical laboratory. All users of the POC glucose monitors should receive thorough education and must regularly pass proficiency testing. POC meters or strips that do not meet the new FDA standards for POC meters used in clinical units should be replaced.

• The hospital should provide guidelines delineating the strengths and weaknesses of the POC meters, and only POC meters that can demonstrate accuracy at the new FDA standard should be allowed in operating rooms or intensive care units. The hospital should consider whether a POC blood-gas analyzer using arterial blood samples for more optimal POC glucose measurement should be made available for use in critical care areas.

• Metrics for glycemic control should be obtained on a periodic, regular basis, and feedback should be provided to the clinical care areas. Benchmarking to national standards should be performed and a continuous quality improvement strategy followed. When problem areas emerge, nonpunitive steps to remedy the problem should be provided.

• Extensive education programs that provide a general understanding of diabetes care standards in the inpatient setting and specific staff responsibilities should be provided. Proficiency standards should be established. Health-care providers and staff should be tested initially and annually to ensure continued proficiency. Education programs should be tailored to the learning styles and strengths of the intended audience.

• All never-events should be given a root-cause analysis and efforts to educate and correct the errors should be undertaken.

• Encourage education of all staff, including ancillary staff such as transportation staff, on safety in insulin therapy.

• Educate nurses on the new technologies they will be responsible for, particularly POC glucose monitoring systems, smart pumps, and other new technologies used in the care of the patient with diabetes.

• Perform studies on a regular basis to ensure that the interventions to improve insulin safety are working as expected. Use objective metrics such as test scores and timely feedback of near misses and errors to obtain a more complete assessment of what is actually taking place in the hospital.

• Checklists should be developed for each provider or specialized care unit so the key steps in their tasks in insulin therapy can be clearly noted and always performed in the correct sequence.

Recommendations to Reduce the Frequency of Diagnostic Errors

• Utilize system-related factors to decrease diagnostic errors, as for example, to provide timely feedback on diagnostic studies that are needed to verify a diagnosis, both radiologic, laboratory, and other consultant-generated studies.

• Educate clinicians as to common pitfalls of clinical reasoning and provide back-up checks on their own diagnoses and real-time team discussions of the patient’s clinical status.

• Encourage clinicians to consider whether their initial diagnoses are correct or whether new information will alter their initial judgment. Premature closure is the most common cognitive error that leads to faulty diagnoses.

• Provide timely consultative expertise to the responsible provider of the diabetes care.

• Encourage the use of diagnostic simulations and case studies to provide training and education and review to improve diagnostic accuracy.

• Transitions of care must be done with the highest level of mindfulness because of the high error rates, particularly with insulin therapy.

• Errors that cause injury should be studied in depth to learn where processes of care and education need to be modified.

• Encourage feedback from patients and families regarding insulin therapy and errors, and incorporate that data in reports.

Conclusion

This chapter discussed different types of errors in insulin therapy and provided examples of each category. Unfortunately, prescribing errors, transcribing errors, dispensing errors, storage errors, administration errors, and monitoring errors are still far too common. The systemic causes of error are most important, because many of the remedies that can be done at this level are much more likely to have the largest impact on making insulin therapy safer. It is also important to look at the performance of individuals involved in the care of the patient receiving the insulin therapy, if we are to create an environment that will always protect the patient from harm and also reduce the number of noninjurious and latent errors. Cognitive psychology helps us better understand the different ways in which our cognitive processes make us vulnerable to error and to help us avoid our own diagnostic errors—the kinds of errors most difficult for the individual to discover and most likely to cause an injurious error. One of the strengths of a culture-of-safety approach is the constant back-up checks and feedback provided to the clinicians, which greatly reduces the risk that a diagnostic error will go undetected. Involvement of the patient and their family in their care is crucial in reducing insulin errors. A culture of safety should strive to always include an informed patient and their family as a central aspect of a team approach in the provision of insulin therapy in the inpatient setting.

Human factors are important to consider in the effort to reduce errors in insulin therapy. Even a highly skilled and knowledgeable provider of care may make a serious error if their sequence of steps during clinical care is interrupted, and these errors often are not noticed when rushed. Yet, along with a propensity for cognitive errors, humans have remarkable cognitive flexibility. A successful culture of safety must include back-up checks to discover these human errors and use the cognitive flexibility of the team members to create an environment that has patient safety as the highest priority.

Finally, the best institutions will need to consider the danger of burdening the clinical team with nonclinical priorities. The more the clinical team is rewarded primarily for nonclinical priorities, the harder the task becomes for making insulin therapy safe for every patient.

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