A pilot study of the use of kaolin-impregnated gauze (Combat Gauze) for packing high-grade hepatic injuries in a hypothermic coagulopathic swine model.

BACKGROUND: Severe hepatic injuries may be highly lethal, and perihepatic packing remains the mainstay of treatment. This is not always successful, particularly in the setting of hypothermia and coagulopathy. Kaolin-impregnated Combat Gauze (CG) is an effective hemostatic dressing used primarily to treat external wounds. The objective of this study was to determine the ability of CG to control severe hemorrhage in hypothermic, coagulopathic swine with a high-grade hepatic injury. METHODS: Anesthetized animals underwent splenectomy and were cooled to 32°C while undergoing a 60% exchange transfusion with Hextend. A grade V liver injury was created in the left middle hepatic lobe. Animals were allowed to freely bleed for 30 s and then randomized to treatment with CG or plain gauze laparotomy pads (PG) applied to the injury site. Animals were then resuscitated with warmed Hextend. RESULTS: There was no difference between groups in preinjury hemodynamic or laboratory values. Animals packed with CG had less blood loss when compared with standard packing (CG = 25 mL/kg versus PG = 58 mL/kg, P = 0.05). There was a trend towards lower hetastarch resuscitation requirements in the CG group (CG = 7 mL/kg versus PG = 44 mL/kg, P = 0.06) but no statistically significant difference in mortality (CG = 13% versus PG = 50%, P = 0.11). Histology of the injury sites revealed more adherent clot in the CG group, but no inflammation, tissue necrosis, or residual material. CONCLUSION: In pigs with severe hepatic injury, Combat Gauze reduced blood loss and resuscitation requirements when compared with plain laparotomy pads. Combat Gauze may be safe and effective for use on severe liver injuries.

Hydrogen fluoride inhalation injury because of a fire suppression system.

Automatic fire suppression systems (FSSs) use hydrofluorocarbons (HFCs) to chemically extinguish fires. At high temperatures, HFC can release hydrogen fluoride (HF), a toxic and potentially lethal gas. We report the deaths of three U.S. military personnel at Bagram Air Base from acute respiratory failure after the FSS in their vehicle received a direct hit from a rocket-propelled grenade. Despite presenting with little to no additional signs of trauma, these individuals all died within 24 hours from HF-induced respiratory failure. When two patients later presented with similar symptoms after damage to their vehicle's FSS, they were aggressively treated with nebulized calcium and positive pressure ventilation. Both survived. The presence of HFC-containing FSSs in military vehicles may lead to future cases of HF inhalation injury, and further research must be done to help rapidly diagnose and effectively treat this injury.

Comparative testing of new hemostatic agents in a swine model of extremity arterial and venous hemorrhage.

OBJECTIVE: To compare advanced hemostatic dressings: HemCon (HC), QuikClot ACS+ (advanced clotting sponge, and two granular agents: Celox (CX) and WoundStat (WS), with a standard field dressing in a swine model of extremity hemorrhage. METHODS: We randomized 30 animals to treatment with a standard dressing or a hemostatic agent applied to a 2 x 6-mm injury in the femoral artery and vein after 45 s of free bleeding. Animals received 500 mL Hextend 15 min after the bleeding commenced without further resuscitation. End point was survival to 120 min or non-survivable blood pressure. RESULTS: Survival to 120 min among treatment groups was 100% (WS), 83% (CX), 67% (HC), and 50% (ACS+). No control animals survived. Postinjury blood loss (mL/kg) was 4.6 (WS), 12.9 (CX), 10.0 (HC), and 15.8 (ACS+) compared to 27.0 for controls. CONCLUSION: All hemostatic dressings result in significantly less blood loss and improved survival over standard gauze dressing.

Preliminary study of the effects of smectite granules (WoundStat) on vascular repair and wound healing in a swine survival model.

BACKGROUND: WoundStat (WS) (TraumaCure, Bethesda, MD) is a topical hemostatic agent that effectively stops severe hemorrhage in animal models. To the best of our knowledge, no survival study has been conducted to ensure long-term product safety. We evaluated vascular patency and tissue responses to WS in a swine femoral artery injury model with survival up to 5 weeks. METHODS: Anesthetized swine received a standardized femoral artery injury with free hemorrhage for 45 seconds followed by WS application. One hour after application, the WS was removed, the wound copiously irrigated, and the artery repaired using a vein patch. Six groups of three animals received WS and were killed either immediately after surgery or at weekly intervals up to 5 weeks. Three control animals were treated with gauze packing and direct pressure followed by identical vascular repair and survival for 1 week. At the time of killing, angiograms were performed, and tissue was collected for histopathology. RESULTS: Hemostasis was complete in all WS animals. All animals survived the procedure, and there were no clinically evident postoperative complications. Vascular repairs were angiographically patent in 15 of 18 animals (83%) receiving WS. Histopathologic examination of WS animals revealed severe diffuse fibrogranulomatous inflammation, early endothelial degeneration with subsequent intimal hyperplasia, moderate myocyte necrosis, and fibrogranulomatous nerve entrapment with axonal degeneration. CONCLUSION: Although an effective hemostatic agent, WS use was associated with a substantial local inflammatory response and neurovascular changes up to 5 weeks postinjury.

Dextran polymer hemostatic dressing improves survival in liver injury model.

BACKGROUND: Improvements in early hemorrhage control could result in more favorable outcomes. Several advanced hemostatic dressings are available; however, none meets the ideal characteristics defined by the United States Army. We studied the effects of a new dextran polymer hemostatic dressing on survival, blood loss, and blood pressure in a swine model of severe liver injury. METHODS: We randomized 12 Yorkshire swine to treatment with either standard laparotomy pads or laparotomy pads coated with a dextran polymer (Bloxx). These dressings are visually identical, and investigators were not informed of the dressing assignment. We transected the left medial lobe of the liver in the anesthetized swine with a large knife, applied dressings immediately, and held pressure for 7 min. The animals received a weight-based maintenance crystalloid infusion without further resuscitation. Endpoints were blood loss, blood pressure, early mortality (120 min), and tissue histology. RESULTS: Baseline and pre-injury characteristics were similar between all animals. Three of six animals in the control group survived for 2 h while all six animals treated with Bloxx survived (P=0.05). Similarly, animals in the Bloxx group experienced less blood loss (10.4+/-8.8 mL/kg versus 28.3+/-13.0 mL/kg, P=0.025) and higher post-injury blood pressure than the control group. Bloxx was not associated with macroscopic or microscopic tissue damage. CONCLUSIONS: Bloxx is superior to standard laparotomy sponges in this model of lethal liver injury. Further study of this dressing is warranted to determine its potential for use in civilian and military trauma.