THE RELATION BETWEEN THE PLATELET-ACTIVATED CLOTTING TEST (HEMOSTATUS) AND BLOOD-LOSS AFTER CARDIOPULMONARY BYPASS

Background: Platelet dysfunction is one of several major causes of ble eding after cardiopulmonary bypass. A timely, simple, point-of-care de terminant of platelet function recently became available for clinical use. Adding platelet-activating factor to conventional activated clott ing time methods (platelet-activated clotting test [PACT]) produces ra pid results (<15 min) and may yield a measure of platelet responsivene ss and whole-blood procoagulant activity. Methods: Blood samples were drawn from 100 patients after cardiac surgery on their arrival in the intensive care unit for PACT, platelet count, prothrombin time (PT), a nd activated partial thromboplastin time (aPTT). Cumulative blood loss at 4, 8, and 12 h after arrival in the intensive care unit and periop erative transfusion requirements were quantitated. Coagulation tests a nd mediastinal blood loss were compared using the Spearman rank test a nd Pearson correlation. The sensitivity and specificity of the laborat ory tests for predicting blood loss were analyzed using the receiver o perating characteristic method. Results: The PT was the only test that correlated with blood loss at 4, 8, and 12 h. The PACT did not correl ate with blood loss at 4, 8, or 12 h, nor did the PACT correlate with the PT or the aPTT. The sensitivity and specificity of the PACT were l ess than those of the PT in predicting blood loss. Only the PT correla ted with platelet and fresh frozen plasma transfusion. Conclusions: Th e PT correlated with blood loss and transfusion requirements and was s uperior to PACT, aPTT, and platelet count for predicting excessive blo od loss after cardiopulmonary bypass.