Background: Warming of IV-administered fluids and blood products is routinely performed in the operating room to help maintain normothermia. Current guidelines recommend against the warming of platelets (PLTs), although there is no evidence for this prohibition in the literature. Our goal in this pilot study was to determine whether the warming of stored PLTs had any effect on their function.
Methods: Ten units of 3-day-old, PLT-rich plasma-derived whole blood PLTs were acquired from the transfusion service. A 5-mL aliquot was taken from each unit before warming (control samples). The remainder of the unit was then passed into a blood-warming device and held there for 2 minutes. Postwarming (warmed) PLT samples were then collected from the effluent end of the warming device. PLT aggregometry assays with adenosine diphosphate, collagen, and arachidonic acid as agonists were performed on the control and warmed samples. Thromboelastography tests were also performed on the control and warmed samples from 6 of the 10 PLT units.
Results: The mean temperature of the control and warmed samples was 22.4°C ± 0.5°C and 37.8°C ± 2.3°C, respectively. There was no significant difference (all P ≥ 0.13) in any of the PLT aggregometry assays or in the maximum amplitude of the thromboelastography test between the control and the warmed samples. The observed mean of only 1 parameter decreased (PLT aggregometry with 5 μM adenosine diphosphate) by 5% (95% confidence interval, -115% to 105%). The maximum change observed was PLT aggregometry with arachidonic acid as agonist, which increased by 116% (95% confidence interval, -91% to 323%).
Conclusion: Although small in size, the results of this study do not support the prohibition against mechanical PLT warming. Studies of PLT activation after warming are also warranted.