The American Association of Blood Banks (AABB) recommends the use of the restrictive red blood cell transfusion threshold, where transfusions are not indicated until hemoglobin levels are 7 g/dL or 8 g/dL. The AABB also recommends the use of standard-issue blood in current blood banking practices, according to updated guidelines published in JAMA.
The AABB examined evidence from 12,587 participants in 31 randomized clinical trials that evaluated either hemoglobin thresholds for red blood cell transfusion (1950 through May 2016) or red blood cell storage duration (1948 through May 2016).
The investigators compared restrictive thresholds, defined as a transfusion not indicated until the hemoglobin levels are 7 g/dL to 8 g/dL, with liberal thresholds, defined as a transfusion not indicated until hemoglobin levels are 9 g/dL to 10 g/dL.
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The evidence from the trials showed that the restrictive threshold was not associated with a higher risk of adverse outcomes, including 30-day mortality, myocardial infarction, cerebrovascular events, pneumonia, or thromboembolism. The researchers also examined 13 trials that included 5515 participants who were randomly assigned to receive fresher blood or standard-issue blood. They found that fresher blood did not improve clinical outcomes.
In their first recommendation, the AABB recommends using the restrictive threshold over the liberal threshold in adult patients who are hemodynamically stable. In addition, among patients who are undergoing orthopedic surgery, cardiac surgery, or who have preexisting cardiovascular disease, the AABB recommends using the restrictive threshold where transfusions are not indicated until hemoglobin levels are 8 g/dL.
The second recommendation states that patients, including neonates, should receive standard-issue blood instead of limiting patients to transfusions with fresher blood that have been stored for less than 10 days.
“If clinicians continue to adopt a restrictive transfusion strategy of 7 g/dL to 8 g/dL, the number of RBC [red blood cell] transfusions would continue to decrease,” the authors of the report wrote. “In addition, standard practice should be to initiate a transfusion with 1 unit of blood rather than 2 units. This would have potentially important implications for the use of blood transfusions and minimize the risks of infectious and noninfectious complications.”
In an accompanying editorial, Mark H. Yazer, MD, and Darrell J. Triulzi, MD, from the Division of Transfusion Medicine, Department of Pathology at the University of Pittsburgh Medical Center, noted that the decision to transfuse should not only be based on hemoglobin level, but that clinical factors, availability of alternative therapies, and patient preferences should be taken into consideration.
“Perhaps direct measurement of tissue oxygenation using noninvasive methods or plasma markers, such as base deficit, lactate, or other biomarkers, coupled with the measurement of hemoglobin level will provide a more clinically relevant indication of the need for RBC transfusion,” they wrote. “Hopefully, future RBC transfusion guidelines will be able to incorporate rigorous evidence from more physiological markers that assess tissue oxygenation.”
Reference
- Carson JL, Guyatt G, Heddle NM, et al. Clinical practice guidelines from the AABB: Red blood cell transfusion thresholds and storage. JAMA. 2016; doi:10.1001/jama.2016.9185.
- Yazer MH, Triulzi, DJ. AABB red blood cell transfusion guidelines: Something for almost everyone. JAMA. 2016; doi: 10.1001/jama.2016.10887.
