Comparison study of Routine Coagulation Tests and Thromboelastography for Detection of Hypocoagulable State in Patients Undergoing Cardiac Surgery on Cardiopulmonary Bypass

Abstract

Background & Aims: Excessive bleeding occurs after cardiac surgeries on cardiopulmonary bypass (CPB) due to various nonsurgical causes. Finding these causes, and correction using appropriate blood product therapy, conventionally routine coagulation tests (RCT) were used, but recently point of care test Thromboelastography being used. We want to compare different RCT with TEG and their value with postoperative blood loss for correlation. Methods: This prospective study was done on patients undergoing cardiac surgery on CPB to correlate between different RCT (PT/INR, aPTT, Fibrinogen level, platelet and Hct) and thromboelstography parameters before heparinization and after reversal with protamine and their correlation with chest-tube output at 24 hours after surgery. Result: We found most RCT parameters changed significantly after cardiopulmonary bypass, but only prebypass platelet count and postbypass PT and fibrinogen level were significantly correlated with the postop blood loss at 24hr. In TEG parameters only MA was changed significantly after bypass but alpha angle and k-time after bypass was significantly correlated with postop blood loss. Routine lab-based coagulation tests and TEG parameters correlation was found in both prebypass and postbypass samples except in few pair. Conclusion: In our study different RCT and TEG parameters correlate and PT and fibrinogen level derangement after bypass and their corresponding part in TEG, k-time and alpha angle correlate significantly with amount of blood loss, so TEG can be used to guide blood component therapy postoperatively in ICU rather than providing empirically due to non-availability of routine coagulation test due to long turnaround time.