Effects of pretransfusion warming of platelets to 35°C on posttransfusion platelet viability

BACKGROUND: Three of four prior studies suggested that warming platelets (PLTs) to 37°C before transfusion into patients with thrombocytopenia gave improved corrected PLT count increments. STUDY DESIGN AND METHODS: Eighteen normal subjects had apheresis PLTs collected that were stored at 22°C for 5 days in two storage bags. One bag of PLTs was warmed to 35°C before infusion, and one remained at 22°C. Three different methods of warming the donor's autologous PLTs before reinfusion were evaluated: warming PLTs to 35°C for 10 or 60 minutes followed by radiolabeling or radiolabeling the PLTs followed by warming to 35°C for 60 minutes. In the first two methods, the warmed PLTs would have returned to 22°C before infusion, and in the third, the PLTs would still be warm when injected. The paired test and control PLTs were radiolabeled with either 111 In or 51 Cr to determine posttransfusion PLT recoveries and survivals. PLT morphology score, pH, hypotonic shock response, extent of shape change, and annexin V binding were determined just before transfusion. RESULTS: There were no differences in posttransfusion autologous radiolabeled PLT recoveries and survivals or in the in vitro measurements for the PLTs maintained at 22°C versus those warmed to 35°C using any of the three methods of PLT warming before infusion. CONCLUSION: Based on these 5‐day‐stored autologous radiolabeled PLT recovery and survival measurements, there is no evidence that warming PLTs to 35°C before infusion improves postinfusion PLT viability.