Clinical Pearls & Morning Reports
Published September 27, 2017
Approximately 11 million units of red cells are transfused annually in the United States, making red-cell transfusion one of the most common medical interventions. Read the latest Review Article.
Q. Volunteer blood donations in the United States are tested for which pathogens?
A. Volunteer blood donations in the United States are tested for syphilis (despite the absence of recent documented cases), hepatitis B virus, human immunodeficiency virus, human T-cell lymphotropic virus, hepatitis C virus, West Nile virus, and Chagas’ disease, with the recent addition of testing for Zika virus. Babesia infection is becoming recognized as a growing problem (associated with 15 to 20% mortality) in some areas of the United States, such as New England, and testing programs are currently being evaluated for possible implementation. Other agents also under study include dengue virus, chikungunya virus, and hepatitis E virus.
Q. What are the American Association of Blood Bank (AABB) guidelines for red-cell transfusion in hospitalized adults who are hemodynamically stable?
A. Overall, the clinical-trial data clearly show the safety of a restrictive threshold of 7 to 8 g of hemoglobin per deciliter in most patients. The American Association of Blood Bank (AABB) guidelines recommend using the restrictive transfusion threshold that was tested in clinical trials: 8 g of hemoglobin per deciliter in patients with preexisting cardiovascular disease and those undergoing cardiac or orthopedic surgery and 7 g per deciliter in most other patients, including those in critical care units. It is important to recognize that adequate evidence from clinical trials is lacking for transfusion strategies in many subgroups of patients, including patients with acute coronary syndromes, those with long-term dependence on transfusion, and patients with hematologic disorders, cancer, thrombocytopenia, or acute neurologic disorders.
Table 1. Red-Cell Transfusion Guidelines Published between 2012 and 2017.
A: Pathogen-reduction technology represents a proactive approach to improving blood safety by broadly inactivating potential infectious agents in the blood component. This technology is now available in the United States for platelets and plasma. The advantages of pathogen-reduction technology would include reduction of residual infections with viruses, bacteria, or parasites that are not detected by current testing systems and prevention of some infections that have not yet been recognized as transmitting disease through transfusion. Pathogen-reduction technology will also inactivate white cells in blood that are not removed by leukoreduction filters, eliminating the need to irradiate red cells in order to prevent transfusion-associated graft-versus-host disease and potentially reducing the risk of febrile nonhemolytic transfusion reactions. It is also anticipated that pathogen-reduction technology could eliminate some of the current donor travel exclusions and testing for some agents for which the risk of breakthrough infections is very low.
A: Because the infectious risks of red-cell transfusion in Western countries are at an all-time low, the noninfectious hazards have become the primary transfusion complications observed in clinical practice. With improvements in recognition and reporting of complications, transfusion-associated circulatory overload is now among the most common hazards of transfusion, reported in 1 to 5% of transfusion episodes. Transfusion-associated circulatory overload is characterized by a cardiogenic pulmonary edema resulting in acute respiratory distress. This reaction occurs most commonly in patients who already have fluid overload as a result of congestive or coronary artery heart disease or acute renal failure. Diagnostic criteria for transfusion-associated circulatory overload include the development or exacerbation of respiratory distress within 6 to 12 hours after transfusion, with evidence of fluid overload, pulmonary edema, an enlarged cardiac silhouette, elevated brain natriuretic peptide levels, a positive fluid balance, and a response to diuretics.