Why is the medical community (re)-interested in cold-stored platelets?

A: In most healthcare settings, the treatment of choice for hypovolemic shock involves administering individual blood components—red cells, plasma, and platelets (PLTs)—proportionally to reflect their constitution in whole blood. In our practice, we previously abandoned using cold-stored PLTs (CS-PLTs) stored at 4°C, in part because studies show CS-PLTs are cleared from circulation faster than room temperature PLTs (RT-PLTs) stored at 22°C. However, although RT-PLTs may be more useful prophylactically in patients with thrombocytopenia, recent research has revealed that cold-induced storage lesions alter the metabolic and functional profile of PLTs such that they effectively curtail hemorrhage.

In light of these findings, healthcare institutions should tailor two different therapeutic strategies for CS-PLTs and RT-PLTs, respectively, based on specific clinical situations. This shift in transfusion practice could impact laboratory technologists cross-trained to work in both clinical labs and blood banks—a role that is becoming more common as many healthcare organizations move toward increased integration. A rise in CS-PLT usage will also have implications for labs that perform infectious diseases testing for blood banks.

Are CS-PLTs regulated by the Food and Drug Administration?

Yes, the regulatory standards for CS-PLTs are enumerated in the Code of Federal Regulations (CFR, 21, 640.24; CFR, 21, 640.25). These standards apply only to PLTs obtained via the Terumo BCT Trima Accel automated blood collection system. According to this regulation, CS-PLTs may be stored at 1-6°C. They must maintain a pH of at least 6.2 and a PLT count of at least 5.5 x 1010 per whole blood-derived unit in at least 75% of tested units, just like RT-PLTs. (As an aside, this last criterion is set at 90% by Standards for Blood Banks and Transfusion Services.)

Unlike RT-PLTs, however, CS-PLTs do not require bacterial testing and they may be stored without agitation for a maximum of 3 days. Importantly, their use is also “restricted only to the resuscitation of actively-bleeding trauma patients” (Transfusion 2017;57;2836-44).

How should blood banks manage their CS-PLT inventory?

An acute/non-acute framework is clinically impactful and naturally lends itself to fostering a dual-PLT inventory. Conveniently, CS-PLTs adhere to the same storage and transport conditions as red blood cells, thawed and liquid plasma components, and whole blood. Altogether these products may be sequestered in a refrigerator, cooler, or other means of transport dedicated to emergent or massive transfusions. RT-PLTs, on the other hand, can be part of a general stockpile of blood products for routine transfusions. This split inventory could reduce wastage due to PLTs deviating from their designated storage temperatures. Moreover, it may reduce costs associated with obsolete bacterial testing and by minimizing PLT outdating, since CS-PLTs have been shown to exhibit decreased risk of bacterial contamination and a longer storage interval due to associated pathogen reduction technologies and platelet additive solutions.

What implications does CS-PLT transfusion have for patient testing?

Given the clinical indication for CS-PLTs, providers should perform a global analysis of acute traumatic coagulopathy when determining whether or not to transfuse a patient with CS-PLTs. The best test for this purpose is point-of-care thromboelastography, which interrogates the entire coagulation system and produces a tracing that identifies abnormal parameters that targeted blood component therapy could correct. The latter information is particularly important when making treatment decisions regarding CS-PLTs because PLTs play a central role in hemostasis after injury, yet are especially prone to acquiring both quantitative and qualitative defects in trauma. Thromboelastography could also be used to monitor resuscitation with CS-PLTs, which otherwise demonstrate a relatively normal functional profile.

Aaron D. Shmookler, MD, FCAP, is assistant professor of pathology and director of the blood bank and stem cell laboratory at West Virginia University, Morgantown.+Email: [email protected]