Effect of thrombelastography on timing of coronary artery bypass grafting

Using Thromboelastography to Predict Blood Loss After Off-Pump Coronary Artery Bypass Grafting

Objective

This study aims to investigate the value of thromboelastography (TEG) in predicting blood loss, and its relationship with blood transfusion demand, during the perioperative period in off-pump coronary artery bypass grafting (OPCABG).

Methods

The data of 398 patients undergoing OPCABG were retrospectively analyzed. Blood was drawn before anesthesia induction (T1) and at 10 minutes after heparin neutralization (T2) for further TEG detection. The patients were divided into two groups based on the results at T2: a TEG normal group and a TEG abnormal group. Logistic regression analysis was used to predict the related factors contributing to the significant increase in perioperative blood loss (more than 20% of the estimated blood volume).

Results

There were 277 (69.6%) patients in the TEG normal group and 121 (30.4%) in the TEG abnormal group. Compared with the TEG normal group, the volume of blood loss, red blood cell count, and volume of plasma transfusion in the TEG abnormal group significantly increased within 24 hours after surgery. The results of the logistic regression analysis identified the use of clopidogrel, platelet count at T2, fibrinogen level at T2, and abnormality in TEG value as independent predictors for the significant increase in perioperative blood loss (P < 0.001).

Conclusion

The abnormality in TEG value after heparin neutralization is correlated with massive hemorrhage and blood transfusion during the perioperative period in OPCABG. TEG detection can assist in clinical treatment and reduce the volume of blood lost in a hemorrhage and the volume of blood required in a transfusion during OPCABG.

Platelet Mapping by Thromboelastography and Whole Blood Aggregometry in Adult Patients Supported by Mechanical Circulatory Support Device on Aspirin Therapy

Patients on mechanical circulatory support (MCS) devices are placed on aspirin and may require platelet function testing (PFT) to monitor the adequacy of therapy. Routine laboratory PFT is performed using whole blood aggregation (WBA) which typically has a long turnaround time (4-5 hours) and may not be readily available. By contrast, platelet mapping by thromboelastography (TPM) can provide results within 45 minutes. The objective of this study was to compare the results of TPM with WBA. We compared platelet mapping maximal amplitude (MA) by TPM with that of arachidonic acid (AA) to WBA with AA by impedance. We analyzed paired samples where both TPM and WBA were available. Of 45 paired samples, 34 were from 29 MCS patients and 11 were from non-MCS patients. When applying institutional interpretation guidelines with an MA_Activator cutoff of ≤40 mm, WBA_AA vs TPM MA_AA in non-MCS and MCS patients correlated well with an accuracy of 100 and 94.4%, respectively. MA_Activator >40 had poor correlation with an accuracy of 37.5%. Irrespective of MA_Activator value, TPM AA inhibition expressed in percent of inhibition had poor accuracy. When used with proper guidelines for interpretation, specifically when MA_Activator ≤ 40 mm, TPM is a suitable and reliable test to use for MCS patients on aspirin.