Evaluation of the hemoglobin balance method for measuring blood loss in cardiac surgery

In cardiac surgery, accurate assessment of blood loss during cardiopulmonary bypass (CPB) is an important clinical task. The hemoglobin balance method is widely used in scientific research; however, its accuracy requires quantitative evaluation. Objectives. To determine the effectiveness of hemoglobin balance monitoring in patients undergoing cardiac surgery using CPB. Material and methods. A prospective, single-center study of 45 patients undergoing cardiac surgery. The accuracy of the hemoglobin balance method was assessed by comparison with the gravimetric method. The analysis was performed using the Bland-Altman method. Bias with 95% confidence intervals (CI) and 95% limits of agreement (LoA) were calculated. The mean absolute error (MAE) and mean absolute percentage error (MAPE) were used to assess the overall accuracy of the method. Conclusions. The hemoglobin balance method is characterized by statistically and clinically significant systematic error and unacceptably wide limits of agreement, which precludes its use for individual clinical monitoring. This method can be used in scientific research, provided its quantitative error characteristics are taken into account.