A comparison study of nearly 1,900 patients published in Perfusion, a peer-reviewed academic journal, questions the long-standing practice of basing blood transfusion decisions on a single low hematocrit measurement result. In the study, titled Is it the Patient or the Physician who Cannot Tolerate Anemia?, researchers showed that a single measure of hematocrit is not a reliable indicator of transfusion need and that lower-than-normal hemoglobin levels have no adverse impact on patients. The study showed that a blood transfusion is largely administered because the physician deems it necessary, not because of quantified changes in the patient's physiology.
The study prospectively analyzed the outcomes of 1,854 patients with high (>21%) and lowlow" (between 17-21%) "are well tolerated and have no adverse impact on outcome," leading researchers to conclude "it is the physician, not the patient, who cannot tolerate low hematocrit levels."
Despite mounting clinical evidence linking adverse patient outcomes to blood transfusions during cardiac surgery, including increased operative mortality and decreased long-term survival, almost half of patients undergoing coronary artery bypass in the U.S. still receive at least one unit of packed red blood cells. In the Perfusion study researchers contend that the decision to unnecessarily transfuse blood in cardiac surgery patients is often based solely on a single low hematocrit level of below 20-22%—a clinical practice more than a half century old.
According to the American Society of Anesthesiologists (ASA) practice guidelines: "red blood cell transfusions should not be dictated by a single hemoglobin 'transfusion trigger' but instead should be based on the patient's risk of developing complications of inadequate oxygenation."
In fact, Dr. Aryeh Shander, President-Elect of the Society for the Advancement of Blood Management (SABM) and the Executive Medical Director for The Institute for Patient Blood Management & Bloodless Medicine and Surgery at Englewood Hospital and Medical Center in Englewood, New Jersey, says that "transfusion guidelines such as the ASA's are becoming increasingly important for the clinician. The transfusion decision is quite complex because of mounting data surrounding risks and negative outcomes coupled with the unproven benefit of red cell transfusions. Deciding to transfuse based on a single static measurement more often results in patients receiving unnecessary transfusions with increased risks, costs and the depletion of an already scarce blood supply. New medical technologies and devices that continuously monitor hemoglobin, oxygen, and perfusion will become essential for transfusions."