STUDIES ON PLATELETS EXPOSED TO OR STORED AT TEMPERATURES BELOW 20-DEGREES-C OR ABOVE 24-DEGREES-C

BACKGROUND: Platelet concentrates (PCs) may be subjected to temperatur es outside 20 to 22 degrees C during shipping or storage, which may ha ve an adverse effect on platelet quality. STUDY DESIGN AND METHODS: Th ese studies systematically evaluated the effect of short-term exposure (less than or equal to 24 hours) of platelets to temperatures above 2 2 degrees or below 20 degrees C as part of standard 5-day PC storage a t 22 degrees C, as well as the effect of long-term storage (5 days) at 24 and 26 degrees C. For the short-term exposure studies, up to 6 uni ts of Day 1 standard PCs were mixed, split, and returned to the contai ners. Test units were then stored without agitation in an incubator at a specific temperature (4, 12, 16, or 18 degrees C) for Various times up to 24 hours, after which they were stored with agitation at 22 deg rees C. One unit acted as control and was stored at 20 to 22 degrees C throughout the 5-day storage period. Loss of platelet discoid shape w as determined photometrically by the extent of shape change assay, by an increase in apparent platelet size, by morphologic evaluation, and by swirling. RESULTS: A gradual loss of platelet discoid shape occurre d at temperatures below 20 degrees C. For similar periods, a greater d ifference between test and control PCs was observed in units held at 4 degrees C than in those held at 16 degrees C. The data were fitted to an equation to relate platelet discoid shape (% of control) to exposu re temperature and time. Assuming that a 20-percent decrease or more i n the extent of shape change assay represents a significant loss in pl atelet viability, the equation predicts that such a loss occurs when t he platelets are exposed to 16 degrees C for greater than or equal to 6 hours, to 12 degrees C for greater than or equal to 10 hours, or to 4 degrees C for 26 hours, whereas exposure to 18 degrees C for less th an or equal to 24 hours has no significant effect. Storage for 5 days at temperatures less than or equal to 26 degrees C was not associated with any significant reduction in platelet discoid shape or other meas ures of platelet quality. CONCLUSION: There was a gradual loss of plat elet discoid shape at exposure temperatures <20 degrees C, which worse ned as temperatures decreased and exposure times increased to 24 hours . This relationship can be described in an equation that could be used as a guideline for allowable exposure conditions.