A novel sponge-based wound stasis dressing to treat lethal noncompressible hemorrhage.

BACKGROUND: Noncompressible hemorrhage is the leading cause of preventable death caused by hemorrhage on the battlefield. Currently, there are no hemostatic agents with the ability to control noncompressible hemorrhage. A wound stasis dressing based upon rapidly expanding cellulose minisponges (MS) was developed and tested in a lethal noncompressible model in swine, by fully transecting subclavian artery and vein. MS were compared with conventional hemostasis dressings, Combat Gauze (CG), in a randomized comparison. METHODS: Sixteen 40-kg swine underwent transection of the subclavian artery and vein through a 4.5-cm aperture. After 30-second free bleeding, randomly selected MS or CG (n = 8 per group) were administered by an independent medical officer. The wound cavity was filled with either MS + no external pressure or one CG + one KERLIX gauze with 3 minutes of external pressure. One reapplication was allowed for CG. Mean arterial pressure was maintained at 60 mm Hg with 500-mL Hextend and lactated Ringer's solution intravenously administered up to a maximum of 10-L until study termination at 1 hour. RESULTS: Mean pretreatment blood loss was similar for MS (719 mL) and CG (702 mL). Primary end points, namely, hemostasis at 4 minutes (MS, 75%; CG, 25%; p = 0.13), hemostasis at 60 minutes (MS, 100%; CG, 25%; p = 0.007), and survival at 60 minutes (MS, 100%; CG, 37.5%; p = 0.026), were improved with MS as were secondary end points, namely, total blood loss (MS, 118 mL; CG 1,242 mL; p = 0.021) and length of application time (MS, 25 seconds; CG, 420 seconds; p = 0.004). CONCLUSION: The use of MS is a novel approach for the rapid, simple treatment of severe noncompressible hemorrhage, which provided statistically significant improvement in hemostasis and survival 60 minutes after injury and a large reduction in blood loss, resuscitation fluid requirement, and medic treatment time compared with conventional hemorrhage control dressings in a swine model.

Long-term outcomes of a chitosan hemostatic dressing in laparoscopic partial nephrectomy.

This study examined the long-term safety and effectiveness of a chitosan hemostatic dressing (CHD) in a porcine laparoscopic partial nephrectomy (LPN) model. Eighteen miniswine underwent treatment of using CHD or Surgicel(®) and Tisseel(®) (S/T) for renal parenchymal hemostasis after LPN. The animals were followed up for 6 and 12 months. Surgical procedure related complications, hematological and blood chemical changes were monitored. Histopathological examination was performed on the treated and untreated tissue and organs. All animals had initial hemostasis and survived without any immediate or delayed complications in both CHD and S/T groups. The animals with CHD treatment left large amounts of chitosan residuals on the resected kidney that associated with greater inflammatory scores when compared to the S/T treated animals. This long-term study showed that CHD residuals remained for 12 months and resulted in local inflammation in the LPN model. Despite lack of signs and symptoms of clinical significance in the animals, a further investigation should be conducted to understand the risk of slow degradation of CHD.

Laparoscopic repair of inferior vena caval injury using a chitosan-based hemostatic dressing.

BACKGROUND: Vena caval injury is a rare but serious complication of laparoscopic surgery, and often requires conversion to an open procedure. The current study investigated whether a vena caval injury could be repaired with a chitosan dressing laparoscopically. METHODS: Six domestic swine were studied. A 4- to 5-mm circumferential incision was created in the inferior vena cava (IVC) and repaired laparoscopically with a chitosan dressing. Neither suture nor additional hemostatic techniques were used. The animals were killed at 30 minutes (n = 2) and at 1 week (n = 4) postoperatively for histopathological analysis. RESULTS: All IVC injuries were successfully repaired laparoscopically using a single chitosan dressing application without recurrent hemorrhaging. Mean operative time was 6 minutes and the blood loss was approximately 55 mL. There was no evidence of clot formation in the repaired vessels. Histology showed that the chitosan dressing had partially degenerated into small particles with moderate chronic inflammatory response 1 week after repair. CONCLUSION: Use of the chitosan-based hemostatic dressing is a simple and reliable technique to control serious hemorrhage from IVC injury during laparoscopic surgery.

Use of a chitosan-based hemostatic dressing in laparoscopic partial nephrectomy.

OBJECTIVES: An external chitosan-based hemostatic bandage has been used to control aggressive bleeding from traumatic injuries. This study was to evaluate the feasibility of using an internal chitosan dressing based on the external platform to control hemorrhage and urinary leakage by sealing off the parenchymal wound following Laparoscopic partial nephrectomy (LPN) in a porcine model. METHODS: Nine heparinized domestic swine underwent bilateral laparoscopic partial nephrectomies involving either a polar (N = 13) or wedge resection (N = 5) followed by treatment with the chitosan dressing. Estimated blood loss, hemostatic score, urinary leakage, operative time, and adhesion score of the chitosan dressing were recorded. RESULTS: Of the 18 procedures, 17 achieved complete hemostasis after deployment of the chitosan dressing. The hemostasis score improved significantly after the deployment in both polar (p < 0.001) and wedge (p = 0.017) resections. The rate of successful pyelocaliceal sealing was 85% (11/13) in polar resections and 60% (3/5) in wedge resections. CONCLUSION: The chitosan-based hemostatic dressing is effective as a primary or supplemental material for controlling parenchymal hemorrhage and sealing the renal collecting system following LPN in the animal model.

Development of a reinforced porcine elastin composite vascular scaffold.

Elastin, a principal structural component of native arteries, has distinct biological and mechanical advantages when used as a biomaterial; however, its low ultimate tensile strength has limited its use as an arterial conduit. We have developed a scaffold, consisting of a purified elastin tubular conduit strengthened with fibrin bonded layers of acellular small intestinal submucosa (aSIS) for potential use as a small diameter vascular graft. The addition of aSIS increased the ultimate tensile strength of the elastin conduits nine-fold. Burst pressures for the elastin composite vascular scaffold (1,396 +/- 309 mmHg) were significantly higher than pure elastin conduits (162 +/- 36 mmHg) and comparable to native saphenous veins. The average suture pullout strength of the elastin composite vascular scaffolds was 14.612 +/- 3.677 N, significantly higher than the pure elastin conduit (0.402 +/- 0.098 N), but comparable to native porcine carotid arteries (13.994 +/- 4.344 N). Cyclic circumferential strain testing indicated that the composite scaffolds were capable of withstanding physiological loading conditions for at least 83 h. Implantation of the elastin composites as carotid interposition grafts in swine demonstrated its superiority to clinically acceptable ePTFE with significantly longer average patency times of 5.23 h compared to 4.15 h. We have developed a biologically based elastin scaffold with suitable mechanical properties and low thrombogenicity for in vivo implantation, and with the potential for cellular repopulation and host integration reestablishing an appropriate elastic artery.