In Vitro Evaluation of a Novel Automatic Intraoperative Blood Loss Monitor

Introduction: Accurate and real-time monitoring of surgical blood loss is essential for ensuring intraoperative safety. However, there is currently no standard way to assess the amount of blood lost in patients during surgery. This study aims to evaluate the accuracy and precision of a new automatic intraoperative blood loss monitor, which can measure both free blood volume and blood content in sponges in real time. Methods: The monitor uses an integrated photoelectric probe to gauge hemoglobin levels in both free blood and blood taken from surgical sponges. These data, combined with initial hemoglobin levels, are processed using specific calculations to determine blood volume. We created 127 diverse free blood samples and 160 blood-containing sponge samples by using fresh pig blood and physiological saline. The monitor then measured these samples. We subsequently compared its measurements with actual values acquired through physical measurements, detecting both agreement and measurement errors. Repeated measurements were performed to calculate the coefficient of variation, thereby evaluating the monitor's precision. Results: The estimated blood loss percentage error of the monitor was 5.2% for free blood, -5.7% for small sponge, -6.3% for medium sponge, and -6.6% for large sponge. The coefficient of variation of free blood with different hemoglobin concentrations measured by the monitor was less than 10%. Bland-Altman analysis showed that the limits of agreement between the monitor and the reference method were all within the acceptable clinical range. Conclusion: The new automatic intraoperative blood loss monitor is an accurate and reliable device for monitoring both free blood and surgical sponge blood, and shows high performance under various clinical simulation conditions.