Common Platelet Products for Transfusion
There are many different platelet products available in the United States, and they have a range of effects depending on the donor, processing, and storage. Misunderstanding the composition of platelet products has been implicated in unnecessary transfusions. The most important questions for the anesthesiologist are, "what is the total platelet content of the product?" and "what volume of plasma is also in the product?" (Figure 1). A single "unit" of "random donor" platelets derived from 500 ml of donor whole blood usually contains at least 55 × 109 platelets in 40 ml of plasma and is stored at 22°C. Transfusing one random-donor unit will raise the recipient platelet count by approximately 5 × 103 cells/μl, and so it is common to make "pools" of five or six random donor units in approximately 200 ml of plasma. In a stable, nonbleeding, and afebrile adult, transfusing one pool will raise the recipient platelet count by approximately 30 × 103 cells/μl, but this varies inversely with body mass and area: the platelet count may only rise 15 to 20 × 103 cells/μl in an obese, 100-kg patient, and may rise 40 to 50 × 103 cells/μl in a thin, 50-kg one. Apheresis, or "single-donor" platelets, are a concentrate collected from a single donation and usually contain 3 to 4 × 10 platelets in approximately 280 ml of plasma. This is equivalent to a platelet pool, and transfusing one apheresis unit will also raise the platelet count by approximately 30 × 103 cells/μl. Random-donor and apheresis platelets are collected in donor plasma with a coagulation factor activity similar to any other unit of plasma. However, apheresis platelets in the United States are often modified by replacing two thirds of the plasma with an additive solution. This improves platelet lifespan and reduces the rate of minor transfusion reactions but may decrease the acute hemostatic utility of the unit compared to apheresis platelets in plasma.[20,21] More than half of the platelet units supplied by the American Red Cross (Washington, D.C.) are stored in additive solution, with a system-wide goal of 70% by the end of 2020 (J. Weiss, M.D., American Red Cross, Madison, Wisconsin, email communication, October 2020).
An illustration of some of the varieties of platelet products available in the United States, how they are collected, and possible modifications to these products. Anticoagulant solutions are typically buffered salt solutions containing citrate and dextrose. Apheresis platelets in platelet additive solution are commonly referred to as "PAS platelets."
Anesthesiology. 2021;134(3):471-479. © 2021 American Society of Anesthesiologists | Lippincott Williams & Wilkins