The Society of Critical Care Anesthesiologists

SOCCA Researchers Expanding Cold Platelet Knowledge

The optimal storage temperature of transfused platelets for surgical and traumatic hemorrhage remains controversial. Standard practice since 1969 has been to transfuse platelets at room temperature (22o). This practice is based on decades old research demonstrating that platelets are removed from the circulation more quickly when stored at 4o than platelets at room temperature.1 Since the most common indication for platelet transfusion is thrombocytopenia due to oncologic disorders in order to prevent bleeding, the increase in circulatory time with room temperature platelets was preferred.

However, the circulatory time of platelets is less important for patients with bleeding where they need to form a clot quickly. Trials in 1973 indicated that cold stored platelets were more hemostatically active than room temperature platelets.2 With more than 30,000 deaths per year in the United States attributable to traumatic bleeding, finding a way to improve platelet transfusion efficacy and availability could save many lives.3 Several potential advantages of cold-stored platelets over room-temperature platelets include: 1) longer storage durations (i.e., 14 days vs. 5-7 days), which minimizes platelet wastage due to outdating; 2) enhanced in vivo hemostatic function; and 3) lower risk of bacterial contamination.4

Members of the SOCCA research committee are aiding in understanding the implications of storage temperature of transfused platelets as investigators on key projects in this field. In anticipation of low inventories, Matthew Warner, MD and colleagues at the Mayo Clinic in Minnesota performed a single-center observational study converting about-to-expire room temperature platelets to cold storage, which extended shelf-life from 5 to 14 days.Through the first 45 days of this process, 61 chilled platelet units were transfused to hemorrhaging patients, with 95% transfused for operative bleeding. The researchers reported positive post-transfusion platelet count increments and adequate hemostasis without adverse events.

The CHIlled Platelet Study (CHIPS) is a Phase III, multicenter trial sponsored by the Department of Defense which aims to compare the effectiveness and safety of chilled platelets versus standard room temperature platelets in 1000 bleeding cardiac surgical patients (NCT04834414). Philip Spinella, MD is the primary investigator (PI) contact overseeing more than 20 sites involved in the study with Brigid Flynn, MD acting as site PI for the University of Kansas. The primary outcome for the CHIPS study is bleeding defined by the Universal Bleeding Score with the main secondary outcome being chest tube output. Adaptive trial design methodology is being used to determine the maximum storage duration of chilled platelets for patients with active bleeding. The trial is expected to be completed by January of 2025.

As bleeding affects many critically ill patients, results from ongoing and future studies evaluating the effectiveness, safety, and availability of chilled platelets are highly anticipated.



  1. Murphy S, et al. N Engl J Med 1969;280:1094-1098.
  2. Becker GA, et al. Transfusion 1973;13::61-8.
  3. Spinella PC, et al. Curr Opin Hematol 2017;24:529-535.
  4. Ketter PM, et al. Transfusion 2019 Apr;59(S2):1479-1489
  5. Warner MA, et al. Transfusion 2021 Jan;61(1):72-77.


Brigid C. Flynn, MD
Secretary, Society of Critical Care Anesthesiologists
University of Kansas Medical Center
Kansas City, Kansas
Matthew Warner, MD
Chair, Research Committee
Mayo Clinic
Rochester, Minnesota