LAUSR

With great interest, we read the recent article by Slezak and colleagues that compares a combination powdered hemostat (PCCT) to a gelatin matrix (SmGM). Using a porcine liver bleeding model, these authors compared treatment with SmGM with PCCT. The assessment of treatment criterion for the study (bleeding severity), as well as success (hemostasis), were evaluated using two methods: bleeding rate, calculated using mass of blood collected on gauze, and bleeding grade using the VIBe scale. However, in this context we would like to draw the attention to the SPOT GRADE (SG), another method of evaluating bleeding severity, which we believe may be conceptually superior to both methods used by Slezak and coworkers. The SG is a reproducible and reliable surface bleeding severity scale; it provides a basis for educating surgeons on target site blood loss. Importantly, the SG bleeding rates are based on predefined input flows delivered via a volumetric pump, whereas the VIBe bleeding rates are based on visual estimates of flow rates. Additional differentiating factors between the bleeding scales are: The SG is a six-level scale, whereas VIBe2 is a 5-level scale, with the SG providing more precise characterization of bleeding severities; The SG was validated in a United States Food and Drug Administration (FDA) approved clinical investigation (NCT02502019), whereas the VIBe scale has not been validated in a clinical setting; The VIBe scale considers a score of 0 as 1.0mL/min, which has not been accepted as hemostatic by FDA; The SG has been used in a prospective, randomized multicenter clinical investigation evaluating the safety and efficacy of a topical hemostatic agent, whereas the VIBe scale has not; and The six-level SG scale also utilizes verbal descriptors, visual descriptors, quantitative flow rates, shock risk class, and expected interventions for targeted bleeding sites; the VIBe scale offers only visual descriptors and flow rates based on sponge weight and visual estimates. In addition, bleeding rate, calculated using difference in mass on gauze held on the bleeding site over 30 seconds, can be subject to inaccuracies or inconsistencies due to the amount of pressure held, folding of the gauze, and absorption of other fluids (i.e., irrigation, blood from other bleeding sites, lymph fluid, etc.), or materials such as PCCT stuck to the gauze, as noted by the authors. We therefore believe that the SG may represent a more accurate and clinically relevant surface bleeding severity scale for use in assessing the comparative performance of hemostatic agents. Thus, translation of the study conclusions to human patients could potentially be more impactful when the data is based on a clinically validated scale.