Evaluation of the hemostatic function of stored platelet concentrates using the platelet function analyzer (PFA-100 (TM))

Background and Objectives, Progressive functional impairment is known to oc cur in platelet concentrates through the storage period. Standardized metho ds providing direct measurement of residual platelet function in stored pla telets are lacking. The purpose of this study was to determine whether a ne w platelet function analyzer (PFA-100(TM)) could provide standardized metho ds for assessing the hemostatic capacity of stored platelets. Design and Methods. The PFA-100 was used to evaluate platelet function In s tored platelets. The instrument can process citrated whole blood but it is unable to process platelet suspensions. Accordingly, the Function of platel et concentrates should be measured following reconstitution of pseudo-whole blood. The analysis of the results Included the closure time (sec) and a p redictive Index, an arithmetical index computed on the basis of the instrum ent's output data: the flow rate, the flow volume, the closure time. Results. A final hematocrit of 58 +/- 2 and a final platelet concentration of 230 +/- 20 x 10(9)/L were used as standardized operative conditions to m easure the function of stored platelet concentrates. The closure time (PFA- CT) and the predictive index (PFA-PI) both resulted to be capable of discri minating platelet concentrates with maintained or impaired function. PFA-PI was more informative than PFA-CI in terms of description of the residual p latelet function. Of the two agonists used, epinephrine (EPI) resulted to b e particularly sensitive for the detection of initial platelet hyporeactivi ty, whereas adenosine 5'-diphosphate (ADP) was particularly useful for meas uring the residual platelet reactivity. Interpretation and Conclusions. PFA-CT and PFA-PI can be standardized; they provide new information about the hemostatic function of stored platelet c oncentrates and can be used to assess the quality of platelet concentrates. (C) 1999, Ferrata Storti Foundation.