Glossary

A List of Commonly Used Terms in Blood Banking

Massive Transfusion

Defined loosely as the rapid administration of a volume of red blood cells roughly equivalent to a “normal” person’s RBC volume. The most common definition is the receipt of 10 units of RBCs within 24 hours, but alternative definitions include: 4 to 5 RBC transfusions within 1 hour, replacement of one-half the patient’s blood volume within 3 hours, or bleeding at a rate of greater than 150 ml/min. The problems with massive transfusion are many, and include more than just whatever issue caused the large-scale hemorrhage leading to a massive transfusion! The list includes electrolyte imbalances (including calcium and potassium problems, especially), hypothermia, and coagulation abnormalities, to name a few.

Problems with coagulation secondary to massive transfusion have been studied extensively, with formula-driven “massive transfusion protocols” (specifying ratios of units of red cells to plasma and sometimes platelets) under evaluation. Currently, standard U.S. practice includes the target of a red cell to plasma ratio of close to 1:1 (one unit of red cells per unit of plasma) in massive transfusion, and sometimes “1:1:1” (with a single unit of whole blood-derived platelets as the last “1”). A major study of this issue published in 2015 called “PROPPR” (JAMA 2015;313(5):471-482) failed to show a substantial difference in mortality at 24 hours between patients receiving a 1:1:1 vs. those receiving more RBCs at a 2:1:1 ratio (that interpretation is not without controversy). Personally, I agree that massive transfusion protocols are essential, because they help everyone both in the transfusion service and in the OR understand exactly what to expect and what products to give. However, I am NOT sure that having a protocol means that a 1:1 red cell to plasma transfusion ratio must always be a part of that protocol! I’m not saying it’s wrong, I’m just saying that I don’t think that we fully understand this whole thing yet. However, trauma surgeons, for the most part, have already made up their minds about this issue.

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