Prediction of excessive bleeding after coronary artery bypass graft surgery: The influence of timing and heparinase on thromboelastography

Abstract

Objective: To compare the ability of thromboelastography, when done at either 10 or 60 minutes after protamine reversal of heparin, to predict excessive bleeding after coronary artery bypass graft (CABG) surgery and to investigate, with the use of heparinase, whether heparin contamination was responsible for the difference, if any. Design: Prospective study. Setting: University hospital, single institution. Participants: Patients undergoing elective CABG surgery (n = 40). Interventions: Blood samples for thromboelastography and routine coagulation tests were collected before induction of anesthesia and at 10 and 60 minutes after protamine reversal of heparin. Blood loss and blood product use were recorded postoperatively. Measurements and Main Results: Of 40 patients undergoing elective CABG surgery, 10 fulfilled the criteria for excessive postoperative bleeding. The sensitivity of thromboelastography to identify patients who bled was better at 60 minutes than at 10 minutes after protamine reversal of heparin (100% v 70%). There was greater specificity (83% v 40% at 10 minutes; 73% v 20% at 60 minutes) and positive predictive value (58% v 28% at 10 minutes; 55% v 29% at 60 minutes) when heparinase was added. At both times, thromboelastography showed only moderate correlation with total blood loss and the use of fresh frozen plasma or platelets or both. Conventional coagulation tests did not predict excessive postoperative bleeding. Conclusion: This study suggests that timing and the use of heparinase influence the predictive ability of thromboelastography, but its usefulness as a sole predictor of post-CABG surgery bleeding is limited. Copyright 2002, Elsevier Science (USA). All rights reserved.