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.

Magnamosis: magnetic compression anastomosis with comparison to suture and staple techniques.

PURPOSE: An ideal anastomosis between hollow viscera should be easily performed, strong, and operator independent. We hypothesized that transluminal attraction between magnets in the intestine could be harnessed to create an intestinal compression anastomosis (magnamosis) with these characteristics. We further hypothesized that variation of attraction force and geometry of compression would affect the quality of the intestinal anastomosis. METHODS: We designed a self-orienting device composed of 2 neodymium-iron-boron magnets affixed to polytetrafluoroethylene moldings. Two topologies were evaluated: one designed with 'uniform' compression and the other with 'gradient' compression. Sixteen young adult pigs (Sus scrofa) underwent laparotomy with creation of a magnetic side-to-side anastomosis: 8 with the uniform device and 8 with the gradient device. Each also had a stapled anastomosis, and 5 had an additional hand-sutured anastomosis. Animals were euthanized at 1, 2, and 3 weeks after operation, then anastomoses were compared on the basis of gross appearance, histology, functional radiography, and mechanical integrity. RESULTS: All magnetic devices formed patent anastomoses without leak. One stapled anastomosis resulted in a contained leak. Mechanical integrity of magnetic anastomoses was not statistically significantly different from staple or suture counterparts, and there was a trend toward greater strength with magnetic anastomoses. Comparison between device types revealed the gradient device trended toward greater strength and earlier patency (67% vs 33% at 1 week). There was no evidence of stenosis, and histologic examination demonstrated tissue remodeling with mucosal and serosal apposition across the magnamoses. CONCLUSIONS: The magnetic compression anastomosis (magnamosis) device is a safe and effective means of sutureless full-thickness intestinal anastomosis with serosal apposition in a pig model. Gradient compression is superior to uniform compression. This technique is compatible with endoscopic and natural orifice approaches.

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.