Chapter 107. Transfusion Biology and Therapy (Part 8)

Nonimmunologic ReactionsFluid OverloadBlood components are excellent volume expanders, and transfusion may quickly lead to volume overload. Monitoring the rate and volume of the transfusion and using a diuretic can minimize this problem.HypothermiaRefrigerated (4°C) or frozen (–18°C or below) blood components can result in hypothermia when rapidly infused. Cardiac dysrhythmias can result fromexposing the sinoatrial node to cold fluid. Use of an in-line warmer will prevent this complication.Electrolyte ToxicityRBC leakage during storage increases the concentration of potassium in the unit. Neonates and patients in renal failure are at risk for hyperkalemia. Preventive measures, such as using fresh or washed RBCs,...
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Chapter 107. Transfusion Biology and Therapy (Part 8) Chapter 107. Transfusion Biology and Therapy (Part 8) Nonimmunologic Reactions Fluid Overload Blood components are excellent volume expanders, and transfusion mayquickly lead to volume overload. Monitoring the rate and volume of thetransfusion and using a diuretic can minimize this problem. Hypothermia Refrigerated (4°C) or frozen (–18°C or below) blood components can resultin hypothermia when rapidly infused. Cardiac dysrhythmias can result fromexposing the sinoatrial node to cold fluid. Use of an in-line warmer will preventthis complication. Electrolyte Toxicity RBC leakage during storage increases the concentration of potassium in theunit. Neonates and patients in renal failure are at risk for hyperkalemia. Preventivemeasures, such as using fresh or washed RBCs, are warranted for neonataltransfusions because this complication can be fatal. Citrate, commonly used to anticoagulate blood components, chelatescalcium and thereby inhibits the coagulation cascade. Hypocalcemia, manifestedby circumoral numbness and/or tingling sensation of the fingers and toes, mayresult from multiple rapid transfusions. Because citrate is quickly metabolized tobicarbonate, calcium infusion is seldom required in this setting. If calcium or anyother intravenous infusion is necessary, it must be given through a separate line. Iron Overload Each unit of RBCs contains 200–250 mg of iron. Symptoms and signs ofiron overload affecting endocrine, hepatic, and cardiac function are common after100 units of RBCs have been transfused (total-body iron load of 20 g). Preventingthis complication by using alternative therapies (e.g., erythropoietin) and judicioustransfusion is preferable and cost effective. Deferoxamine and other chelatingagents are available, but the response is often suboptimal. Hypotensive Reactions Transient hypotension may be noted among transfused patients who takeangiotensin-converting enzyme (ACE) inhibitors. Since blood products containbradykinin that is normally degraded by ACE, patients on ACE inhibitors mayhave increased bradykinin levels that cause hypotension. The blood pressuretypically returns to normal without intervention. Immunomodulation Transfusion of allogeneic blood is immunosuppressive. Multiply transfusedrenal transplant recipients are less likely to reject the graft, and transfusion mayresult in poorer outcomes in cancer patients and increase the risk of infections.Transfusion-related immunomodulation is thought to be mediated by transfusedleukocytes. Leukocyte-depleted cellular products may cause lessimmunosuppression, though controlled data have not been obtained and areunlikely to be obtained as the blood supply becomes universally leukocyte-depleted. Infectious Complications Nucleic acid amplification testing (NAT) began in 1999 to screen donatedblood for the presence of HIV and hepatitis C virus (HCV) RNA. Since 2003 NAThas been used to detect West Nile virus (WNV) RNA in donated blood. Viral Infections Hepatitis C Virus Blood donations are tested for antibodies to HCV and HCV RNA. Fewerthan 200 HCV RNA-positive, antibody-negative donors have been found. The riskof acquiring HCV through transfusion is now calculated to be approximately 1 in2,000,000 units. Infection with HCV may be asymptomatic or lead to chronicactive hepatitis, cirrhosis, and liver failure. Human Immunodeficiency Virus Type 1 Donated blood is tested for antibodies to HIV-1, HIV-1 p24 antigen, andHIV RNA using NAT. Approximately a dozen seronegative donors have beenshown to harbor HIV RNA. The risk of HIV-1 infection per transfusion episode is1 in 2 million. Antibodies to HIV-2 are also measured in donated blood. No casesof HIV-2 infection have been reported in the United States since 1992. Hepatitis B Virus Donated blood is screened for HBV using assays for hepatitis B surfaceantigen (HbsAg). NAT testing is not practical because of slow viral replicationand lower levels of viremia. The risk of transfusion-associated HBV infection is 1in 63,000 units, twentyfold greater than for HCV. Vaccination of individuals whorequire long-term transfusion therapy can prevent this complication.