Utility of thromboelastography versus routine coagulation tests for assessment of hypocoagulable state in patients undergoing cardiac bypass surgery

Introduction: Peri-operative monitoring of coagulation is important to diagnose potential cause of hemorrhage, to manage coagulopathy and guide treatment with blood products in patients undergoing cardiac surgery with cardiopulmonary bypass. This study was done to evaluate usefulness of Thromboelastography (TEG) and routine coagulation tests (RCT) in assessing hemostatic changes and predicting postoperative bleeding in patients undergoing cardiac surgery with cardiopulmonary bypass. 

Methods: Fifty adult patients undergoing cardiac surgery with cardiopulmonary bypass were enrolled in this prospective study. Preoperative and post-operative samples were collected for routine coagulation tests and TEG. Regression analysis and test of significance using Pearson’s correlation coefficient was performed to assess correlation between routine coagulation tests and corresponding TEG parameters .Regression analysis was done to study relation between blood loss at 24 hours and various coagulation parameters. 

Results: The Routine coagulation test i.e. PT, INR, APTT showed no significant correlation with corresponding TEG parameters in pre-operative samples. However platelet count significantly correlated (p = 0.004) with MA values in postoperative samples. A significant correlation (p = 0.001) was seen between fibrinogen levels and alpha angles as well as with MA in both baseline preoperative and postoperative samples. TEG parameters R time and MA in postoperative samples were the only parameters that predicted bleeders with fair accuracy. 

Conclusion: Though the techniques of RCT and TEG are different, a few RCT e.g. platelet count and fibrinogen correlated with corresponding TEG parameters i.e. MA and Alpha angle. TEG parameters (R time and MA in postoperative samples) were able to predict blood loss better than RCT.