In Vitro Evaluation of a Novel System for Monitoring Surgical Hemoglobin Loss

Abstract

Background Accurate measurement of intraoperative blood loss is an important clinical variable in managing fluid resuscitation and avoiding unnecessary transfusion of blood products. In this study, we measured surgical blood loss using a tablet computer programmed with a unique algorithm modeled after facial recognition technology. The aim of the study was to assess the accuracy and performance of the system on surgical laparotomy sponges in vitro. Study Design and Methods Whole blood samples of pre-measured hemoglobin (Hb) and volume were reconstituted from units of human packed red blood cells and plasma and distributed across surgical laparotomy sponges. Normal saline was added to simulate the presence of varying levels of hemodilution and/or irrigation use. Soaked sponges from four different manufacturers were scanned using the Triton System with Feature Extraction Technology (Gauss Surgical, Inc., Palo Alto, USA) under three different ambient light conditions in an operating room. Accuracy of Hb loss measurement was evaluated relative to the pre-measured values using linear regression and Bland-Altman analysis. Correlations between studied variables and measurement bias were analyzed using nonparametric tests. Results The overall mean percent error for measure of Hb loss for the Triton System was 12.3% [95% CI 8.2 to 16.4%]. A strong positive linear correlation between the pre-measured and actual Hb masses was noted across the full range of intraoperative lighting conditions, including (A) high (r = 0.95 [95% CI 0.93–0.96]), (B) medium (r = 0.94 [95% CI 0.93–0.96]), and (C) low (r = 0.90 [95% CI 0.87–0.93]) mean ambient light intensity. Bland-Altman analysis revealed a bias of 0.01 g [95% CI −0.03 to 0.06 g] of Hb per sponge between the two measures. The corresponding lower and upper limits of agreement were −1.16 g [95% CI −1.21 to −1.12 g] per sponge and 1.19 g [95% CI 1.15 to 1.24 g] per sponge, respectively. Measurement bias of estimated blood loss and Hb mass using the new system were not associated with the volume of saline used to reconstitute the samples (p = 0.506 and p = 0.469, respectively), suggesting that the system is robust under a wide range of sponge saturation conditions. Conclusion Mobile blood loss monitoring using the Triton system is accurate in assessing Hb mass on surgical sponges across a range of ambient light conditions, sponge saturation, saline contamination, and initial blood Hb. Utilization of this tool could significantly improve the accuracy of blood loss estimates.

Development and validation of an intraoperative bleeding severity scale for use in clinical studies of hemostatic agents

“…Feature extraction technology, however, is a recent advancement that measures hemoglobin loss in real time with a high degree of accuracy. [38][39][40] Hemoglobin loss, however, does not represent blood volume loss, which determines bleeding severity. The applicability of this technology is, therefore, limited in its use for determining bleeding severity.…”

Accurate Measurement of Intraoperative Blood Loss Improves Prediction of Postoperative Hemoglobin Levels

“…The technology can also measure the hemoglobin content of fluid collected in surgical suction canisters. The accuracy of the method is not affected by the admixture of irrigation or other fluids or the ambient lighting condition [13]. In the historical group (system not used) a visual estimation of blood loss was determined by consensus between the attending surgeon and anesthesiologist.…”

“…The performance of the device has been validated in bench-top and clinical settings [12][13][14]. To demonstrate the utility of this device, we postulated that accurate measurement of operative blood loss would facilitate prediction of postoperative hemoglobin levels following restoration of normovolemia.…”

Accurate Measurement of Intraoperative Blood Loss during Wound Excision Leads to More Appropriate Transfusion and Reduced Blood Utilization

“…The technology can also measure the hemoglobin content of fluid collected in surgical suction canisters. The performance of the device has been validated previously in bench-top and clinical settings and the results are accurate despite contamination with asanguinous fluids [13][14][15].…”