Studies on platelets exposed to or stored at temperatures below 20 degrees C or above 24 degrees C

Platelet concentrates (PCs) may be subjected to temperatures outside 20 to 22 degrees C during shipping or storage, which may have an adverse effect on platelet quality.

These studies systematically evaluated the effect of short-term exposure (< or = 24 hours) of platelets to temperatures above 22 degrees or below 20 degrees C as part of standard 5-day PC storage at 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 units of Day 1 standard PCs were mixed, split, and returned to the containers. 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 degrees 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 was determined photometrically by the extent of shape change assay, by an increase in apparent platelet size by morphologic evaluation, and by swirling.

A gradual loss of platelet discoid shape occurred at temperatures below 20 degrees C. For similar periods, a greater difference 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 exposure temperature and time. Assuming that a 20-percent decrease or more in the extent of shape change assay represents a significant loss in platelet viability, the equation predicts that such a loss occurs when the platelets are exposed to 16 degrees C for > or = 16 hours, to 12 degrees C for > or = 10 hours, or to 4 degrees C for > or = 6 hours, whereas exposure to 18 degrees C for < or = 24 hours has no significant effect. Storage for 5 days at temperatures < or = 26 degrees C was not associated with any significant reduction in platelet discoid shape or other measures of platelet quality.

There was a gradual loss of platelet discoid shape at exposure temperatures < 20 degrees C, which worsened 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.