Читать книгу Transfusion Medicine - Jeffrey McCullough - Страница 113

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of citrate solutions to donors, resulting from the massive autologous retransfusion of 4–6 L of their blood may be withdrawn, passed through the instrument, citrated, and returned to them during the procedure.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].