A study of aspirin induced changes in bleeding time, platelet aggregation, and sonoclot® coagulation analysis in humans

The purpose of this study was to determ ine w hether or not a new er test of p la te le t function, Sonoclot® coagulation analysis, can identify the patients who develop significant prolongation of bleeding tim e after aspi­ rin ingestion. Tem plate bleeding time, platelet aggregation in response to arachidonic acid, collagen, epinephrine, adenosine diphosphate, and risto­ cetin, and Sonoclot® coagulation analysis were performed before and after ingestion of aspirin in 22 adult volunteers. Mean bleeding tim e increased from 5.32 ± 2.16 min to 7.34 ± 2 .1 min, bu t rem ained w ithin normal range (2.5 to 9 min). There was marked intersubject variability in the effect of aspirin on bleeding time, and difference betw een men and wom en was not significant. T here was significant decrease in p la te le t aggregation in response to arachidonic acid, collagen and epinephrine. Sonoclot® coagu­ lation analysis did not show significant effect of aspirin administration. There was no correlation among changes in bleeding time, p latelet aggre­ gation, and Sonoclot® coagulation analysis. Five patients with known plate­ let function disorders and prolonged bleeding times (mean = 18.5 min, range 14 to 22) without any other coagulation abnormalities were also stud­ ied. In four of these patients who had normal platelet count, Sonoclot® graphs were morphologically similar to those in the volunteers with normal b leeding times, bu t in one patient with thrombocytopenia, morphology was altered. It is our conclusion that Sonoclot® coagulation analysis is unlikely to identify patients with prolonged bleeding time in whom platelet count and other coagulation factors are normal. * P re se n ted a t th e 64th C ongress o f In terna tional A nesthesia R esearch Society, H ono lu lu , H I, M arch 1990. t S u p p o rted by a g ran t from Sience, Inc ., M orrison, C O 80465. t Sen d re p rin t req u ests to Satw ant K. Sam ra, M .D ., D ep artm en t o f A nesthesio logy, Box 48, 1G323 U niversity H osp ita l, 1500 E . M edical C en te r D rive, A nn Arbor, M I 48109-0048. H D eceased .