SPOT GRADE II: Clinical Validation of a New Method for Reproducibly Quantifying Surgical Wound Bleeding: Prospective, Multicenter, Multispecialty, Single-Arm Study

Efficacy of a novel polyoxazoline-based hemostatic patch in liver and spleen surgery

BACKGROUND

A new hemostatic sealant based on a N-hydroxy-succinimide polyoxazoline (NHS-POx) polymer was evaluated to determine hemostatic efficacy and long-term wound healing and adverse effects in a large animal model of parenchymal organ surgical bleeds.

METHODS

Experiment 1 included 20 pigs that were treated with two NHS-POx patch prototypes [a gelatin fibrous carrier (GFC) with NHS-POx and an oxidized regenerated cellulose (ORC) with poly(lactic-co-glycolic acid)-NHS-POx:NU-POx (nucleophilically activated polyoxazoline)], a blank gelatin patch (GFC Blank), TachoSil^® and Veriset™ to stop moderate liver and spleen punch bleedings. After various survival periods (1-6 weeks), pigs were re-operated to evaluate patch degradation and parenchymal healing. During the re-operation, experiment 2 was performed: partial liver and spleen resections with severe bleeding, and hemostatic efficacy was evaluated under normal and heparinized conditions of the two previous prototypes and one additional NHS-POx patch. In the third experiment an improved NHS-POx patch (GATT-Patch; GFC-NHS-POx and added 20% as nucleophilically activated polyoxazoline; NU-POx) was compared with TachoSil^®, Veriset™ and GFC Blank on punch bleedings and partial liver and spleen resections for rapid (10s) hemostatic efficacy.

RESULTS

NHS-POx-based patches showed better (GFC-NHS-POx 83.1%, ORC-PLGA-NHS-POx: NU-POx 98.3%) hemostatic efficacy compared to TachoSil^® (25.0%) and GFC Blank (43.3%), and comparable efficacy with Veriset™ (96.7%) on moderate standardized punch bleedings on liver and spleen. All patches demonstrated gradual degradation over 6 weeks with a reduced local inflammation rate and an improved wound healing. For severe bleedings under non-heparinized conditions, hemostasis was achieved in 100% for Veriset™, 40% for TachoSil and 80-100% for the three NHS-POx prototypes; similar differences between patches remained for heparinized conditions. In experiment 3, GATT-Patch, Veriset™, TachoSil and GFC Blank reached hemostasis after 10s in 100%, 42.8%, 7.1% and 14.3%, respectively, and at 3 min in 100%, 100%, 14.3% and 35.7%, respectively, on all liver and spleen punctures and resections.

CONCLUSIONS

NHS-POx-based patches, and particularly the GATT-Patch, are fast in achieving effective hemostatic sealing on standardized moderate and severe bleedings without apparent long-term adverse events.

The evaluation of Hemoblast Bellows for arterial hemorrhage control in a swine model of vascular injury

Background

Uncontrolled hemorrhage remains the leading cause of preventable death on the battlefield. Hemostatic agents have increased in use and have been shown to improve survival. Combat Gauze (CG) is the most-used hemostatic gauze recommended by the Committee of Tactical Combat Casualty Care. Hemoblast Bellows (HB), a product FDA-approved for intraoperative hemorrhage, contains thrombin which differentiates it from CG and other kaolin-based hemostatic agents and has not been evaluated in the pre-hospital setting. This study aimed to compare HB to CG, in a standard swine arterial hemorrhage model.

Methods

Dilutional coagulopathy and hypothermia were induced in anesthetized Yorkshire-cross swine. The femoral artery was isolated and a 6 mm femoral arteriotomy was made. After a 30 s free bleed, randomly assigned hemostatic agent(s) from one of the three treatment groups: HB only, CG only, and HB + CG were applied and direct pressure was held for 3 min. At 30 min, the ipsilateral lower extremity was mobilized with a series of hip movements. Primary endpoints included blood loss, rebleeding, thromboelastogram (TEG) values, SPOT GRADE(TM) values, and mean arterial pressure (MAPs), which were monitored during the 150-min observation period.

Results

There were no significant differences between the treatment groups for blood loss, rebleeding, lactate, TEG values, SPOT GRADE, or MAPs for all time points examined.

Conclusions

We found no significant differences between the treatment groups for any of the included data points. These results suggest that arterial hemorrhage control with HB alone and HB + CG is not significantly different from hemorrhage control with CG only. These findings should not deter us from a continued investigation of hemostatic agents but should stimulate our search for superior hemorrhage control agents and novel delivery mechanisms. Continued innovation with such products may overcome the product limitations that we observed during testing and may prove to be a more relevant product for the point-of-injury.

Applicability and reproducibility of the validated intraoperative bleeding severity scale (VIBe scale) in liver surgery: A multicenter study

BACKGROUND

Bleeding is an intraoperative and postoperative complication of liver surgery of concern, and yet evidence to support utility and reproducibility of bleeding scales for liver surgery is limited. We determined the reproducibility of the clinician-reported validated intraoperative bleeding severity scale and its clinical value of implementation in liver surgery.

METHODS

In this descriptive and observational multicenter study, we assessed the performance of liver surgeons instructed on the clinician-reported intraoperative bleeding severity scale using training videos that covered all 5 grades of bleeding severity. Surgeons were stratified according to years of surgical experience and number of surgeries performed per year based on a median split in low and high values. Intraobserver and interobserver agreement was assessed using Kendall's coefficient of concordance (Kendall's W).

RESULTS

Forty-seven surgeons from 10 hospitals in Spain participated in the study. The overall intraobserver concordance was 0.985, and the overall interobserver concordance was 0.929. For "high experience" surgeons, the intraobserver and interobserver agreement values were 0.990 and 0.941, respectively. For "low experience" surgeons, the intraobserver and interobserver agreement was 0.981 and 0.922, respectively. Regarding the annual number of surgeries, intraobserver and interobserver agreement values were 0.995 and 0.940, respectively, for surgeons performing >35 surgeries per year, with 0.979 and 0.923, respectively, for surgeons who perform ≤35 surgeries year.

CONCLUSION

The clinician-reported intraoperative bleeding severity scale shows high interobserver and intraobserver concordance, suggesting it is a useful tool for assessing severity of bleeding during liver surgery; years of surgical experience and number of annual procedures performed did not affect the applicability of the clinician-reported intraoperative bleeding severity scale.

VIBe Scale: Validation of the Intraoperative Bleeding Severity Scale by Spine Surgeons

BACKGROUND

The Validated Intraoperative Bleeding Scale (VIBe Scale) was initially validated with surgeons who operate on cardiothoracic, abdominal, and pelvic cavities and fulfilled criteria for a clinician-reported scale. However, there is a need for a tool to aid in intraoperative blood management during spine surgeries. The purpose of the present study was to establish the reliability and consistency of the VIBe Scale as a tool for spine surgeons to assess intraoperative bleeding.

METHODS

Orthopedic (n = 16) and neurological (n = 9) spine surgeons scored videos depicting surgical bleeding and assessed the VIBe Scale's relevance and clarity. Inter- and intraobserver agreement (Kendall's W) were calculated for all surgeons and pooled with responses from the original study to establish agreement across specialties.

RESULTS

All of the spine surgeons indicated that the scale was clinically relevant for evaluating hemostasis and could be implemented in a clinical study. Twenty-two spine surgeons (88%) reported that the scale represents the range of bleeding site sizes and severities expected in their practice. Twenty-four spine surgeons (96%) indicated that the scale would be useful in communicating bleeding severity with other members of the surgical team. Interobserver agreement was acceptable (0.79) for orthopedic specialists, appreciable (0.88) for neurological specialists, and appreciable (0.88) for the combined specialists. Intraobserver agreement was excellent for orthopedic (0.91) and neurological (0.91) spine surgeons and excellent (0.96) for the combined specialists.

CONCLUSIONS

The results highlight the reliability of the VIBe Scale and potential utility for quantifying intraoperative blood loss in spine surgery.

LEVEL OF EVIDENCE: 3

CLINICAL RELEVANCE

The VIBe Scale may be useful for evaluating the efficacy of untested intraoperative hemostatic agents and for comparing the relative efficacy of 2 or more analogous agents. It may also prove useful for intraoperative staff by quantifying ongoing intraoperative blood loss and correlating losses with the potential transfusion and intraoperative hemostatic agent requirements.

Hemostats in Spine Surgery: Literature Review and Expert Panel Recommendations

Bleeding in spine surgery is a common occurrence but when bleeding is uncontrolled the consequences can be severe due to the potential for spinal cord compression and damage to the central nervous system. There are many factors that influence bleeding during spine surgery including patient factors and those related to the type of surgery and the surgical approach to bleeding. There are a range of methods that can be employed to both reduce the risk of bleeding and achieve hemostasis, one of which is the adjunct use of hemostatic agents. Hemostatic agents are available in a variety of forms and materials and with considerable variation in cost, but specific evidence to support their use in spine surgery is sparse. A literature review was conducted to identify the pre-, peri-, and postsurgical considerations around bleeding in spine surgery. The review generated a set of recommendations that were discussed and ratified by a wider expert group of spine surgeons. The results are intended to provide a practical guide to the selection of hemostats for specific bleeding situations that may be encountered in spine surgery.