Background: Early detection of a risk of postoperative bleeding is essential in cardiac surgery patients. The aim of the present study was to evaluate the utility of the first derivative curve (the V-curve) of the clotting waveform of rotational thromboelastometry (ROTEM) in terms of predicting bleeding after cardiac surgery.
Methods: We retrospectively analysed 534 cardiac surgery patients. We used the chest tube output during the stay in the intensive care unit to divide patients into a higher blood loss group (HBL group; the fourth quartile) and a lower blood loss group (LBL group; the lower quartiles). We performed multivariable logistic regression using the V-curve parameters and potential confounders including conventional ROTEM parameters.
Results: In the multivariable model, the adjusted odds ratios for HBL of patients with a lower maximum clotting velocity (MaxVel ≤9 mm*100 s-1) as revealed by extrinsically activated ROTEM (EXTEM), and the area under the velocity curve (AUC ≤988 mm*100) of the fibrin-based extrinsically activated ROTEM (FIBTEM), both measured at skin closure in the end of surgery, were 1.78 (95% CI 1.03 to 3.07) and 2.14 (95% CI 1.20 to 3.82), respectively. However, conventional ROTEM parameters were not included in the final model. Additionally, lower EXTEM MaxVel and FIBTEM AUC values were associated with the need for a higher transfusion volume, longer postoperative intensive care unit and hospital stays, and more frequent re-exploration to control bleeding.
Conclusions: The ROTEM V-curve parameters can predict postoperative bleeding and clinical outcomes after cardiac surgery.