Testing of modified zeolite hemostatic dressings in a large animal model of lethal groin injury.
BACKGROUND
We have previously identified a granular zeolite hemostat (ZH) as an effective agent for control of severe bleeding, and it is currently being used by the US troops in the battlefield. ZH causes an exothermic reaction on application, which theoretically can be decreased by altering its chemical composition or changing its physical properties. However, the effect of these alterations on the hemostatic efficacy is unknown. We tested modified zeolites and a chitosan based dressing against controls in a swine model of battlefield injury.


METHODS
A complex groin injury was created in 60 swine (40-55 kg). This included semi-transection of the proximal thigh (level of inguinal ligament), and complete division of the femoral artery and vein. After 3 minutes, the animals were assigned to (1) no dressing (ND), (2) standard dressing (SD), (3-5) SD + chemically modified ZHs, where calcium was substituted with sodium (Na), barium (Ba), or silver (Ag), respectively, (6) SD + physically modified ZH, where "beads" were packaged in a fabric bag, (7) SD + chitosan based dressing (CD). Resuscitation was started 15 minutes after application of dressing (500 mL of 6% hetastarch over 30 minutes). Survival for 180 minutes was the primary endpoint for this study. In addition, blood loss, wound temperatures, and histologic tissue damage were recorded.


RESULTS
Mortality in the group that was treated with the application of bagged ZH was 10% versus 100% in the no dressing group and 50% in the SD group (p < 0.05 vs. ND and SD groups). The Na ZH group had a mortality rate of 43%, whereas application of Ba and Ag substituted zeolites, and CD were associated with a mortality rate of 25%. Ionic substitution of zeolite decreased the in vivo temperature peak by 5 to 10 degrees C. No histologic evidence of tissue necrosis was noted in this experiment.


CONCLUSIONS
The use of zeolite hemostat can control hemorrhage and dramatically reduce mortality from a lethal groin wound. Modifications of zeolite hemostat can decrease the exothermic reaction and attenuate tissue damage.
Ahuja
Naresh
N
Department of Surgery, Uniformed Services University of the Health Sciences, Bethesda, Maryland, USA.
Ostomel
Todd A
TA
Rhee
Peter
P
Stucky
Galen D
GD
Conran
Richard
R
Chen
Zheng
Z
Al-Mubarak
Ghada A
GA
Velmahos
George
G
Demoya
Marc
M
Alam
Hasan B
HB
D000818:Animals; D001458:Bandages; D001464:Barium; D048271:Chitosan; D004195:Disease Models, Animal; D006119:Groin / Q000293:injuries*; D006490:Hemostatics; D007474:Ion Exchange; D012771:Shock, Hemorrhagic / Q000209:etiology / Q000517:prevention & control*; D012834:Silver; D012964:Sodium; D013552:Swine; D014950:Wounds, Penetrating / Q000150:complications / Q000628:therapy*; D017641:Zeolites
D006490:Hemostatics; D017641:Zeolites; D001464:Barium; D012834:Silver; D048271:Chitosan; D012964:Sodium