New foam could treat victims of internal hemorrhaging
Polyurethane polymer forms inside a patient's body upon injection of two liquid phases
WASHINGTON — A new type of injectable foam that molds to organs and slows hemorrhaging could be used on the battlefield by military first responders.
The technology, developed under the Defense Advanced Research Projects Agency’s Wound Stasis System program, resulted in 72 percent survival rate at three hours post-injury in testing.
Wound Stasis performer Arsenal Medical, Inc. developed the foam-based product to control hemorrhaging in a patient’s intact abdominal cavity for at least one hour, based on swine injury model data.
The foam is designed to be administered on the battlefield by a combat medic, and is easily removable by doctors during surgical intervention at an appropriate facility.
Pre-clinical data on the foam treatment was presented at the 2012 Annual Meeting of the American Association for the Surgery of Trauma in Kauai, Hawaii.
These data demonstrated the ability of the foam to treat severe hemorrhage for up to three hours in a model of lethal liver injury. During testing, minimally invasive application of the product reduced blood loss six-fold and increased the rate of survival at three hours post-injury to 72 percent from the eight percent observed in controls.
"According to the U.S. Army Institute of Surgical Research, internal hemorrhage is the leading cause of potentially survivable deaths on the battlefield, so the Wound Stasis effort should ultimately translate into an increased rate of survival among warfighters," Brian Holloway, DARPA program manager, said.
"If testing bears out, the foam technology could affect up to 50 percent of potentially survivable battlefield wounds."
The foam is actually a polyurethane polymer that forms inside a patient's body upon injection of two liquid phases, a polyol phase and an isocyanate phase, into the abdominal cavity, according to DARPA.
As the liquids mix, two reactions are triggered.
First, the mixed liquid expands to approximately 30 times its original volume while conforming to the surfaces of injured tissue. Second, the liquid transforms into solid foam capable of providing resistance to intra-abdominal blood loss. The foam can expand through pooled and clotted blood and despite the significant hydrostatic force of an active hemorrhage, a press release said.
In tests, removal of the foam took less than one minute following incision by a surgeon. The foam was removed by hand in a single block, with only minimal amounts remaining in the abdominal cavity, and with no significant adherence of tissue to the foam.
Features appearing in relief on the extracted foam showed conformal contact with abdominal tissues and partial encapsulation of the small and large bowels, spleen, and liver. Blood absorption was limited to near the surface of the foam; the inside of the foam block remained almost uniformly free of blood, according to tests.
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