Review of: Ahuja N, Ostomel TA, Rhee P, et al: Testing of modified zeolite hemostatic dressings in a large animal model of lethal groin injury. Journal of Trauma. 61:1312 1320, 2006.
This study examined the ability of a commercially available material called zeolite hemostat to control severe bleeding in a swine model. The researchers transected the femoral artery and vein and allowed the wound to bleed for three minutes. They then packed the wounds with various types of dressings. The control was no dressing at all, and comparison groups involved standard gauze; zeolite that was chemically modified with sodium, barium, or silver; zeolite physically modified with beads placed in a fabric bag; and chitosan-based dressing.
Mortality was the final outcome as measured by the ability of the dressing to control the bleeding. All the pigs with no dressings died. Mortality for the gauze dressing, chemically modified zeolite, and chitosan-based dressings were 50%, 43%, and 25% respectively. The mortality rate for the physically modified zeolite dressing was 10%
The authors further discovered that the previously observed exothermic reaction of unmodified zeolite was significantly reduced by the new delivery method.
Battlefield medicine has taught us that the major cause of death after surviving the initial injury is the inability to control bleeding. Soldiers, who would have otherwise survived their injuries, are dying because traditional attempts to control bleeding (such as using tourniquets) have failed. This has led to an aggressive search for an externally applied bleeding-control agent that could also have utility in EMS.
Two such products are currently on the market. Both have been found to control bleeding, but both have their pros and cons. The chitosan-based dressing must often be cut and molded to conform to the wound and must be placed into direct contact with the bleeding source to be most effective.
The zeolite agent, which was initially released as a powder, was found to have an unacceptable exothermic (heat-producing) action, which potentially worsened the injury. This study found that by impregnating the zeolite into beads that were then placed in a fabric pouch, the exothermic reaction was significantly reduced.
When examining claims by the makers of these hemostatic agents, weight should be given to research not funded by either manufacturer. What role either of these agents will play in EMS has yet to be defined. However, as history has shown, what we learn in the battlefield soon finds its way into our practice on the street. I believe this will be the case for externally applied hemostatic agents.