Halting the blood loss

May 15, 2017 by Sharon Adams
The XStat Rapid Homeostasis System was battle- tested a year ago.
Xstat

Combat soldiers who have suffered battlefield wounds have never had a better chance of survival than they have today.

Due to improvements in battlefield medicine and evacuation, 92 per cent of U.S. soldiers wounded in Iraq and Afghanistan made it home alive, compared to about 75 per cent in the Vietnam War. Former Canadian Armed Forces surgeon-general Hans Jung said in 2010 that if wounded troops could make it back to NATO’s Role 3 hospital at Kandahar Airfield in Afghanistan, “they have a 97 per cent chance of making it all the way back to Canada alive.”

Experience on 21st-century battlefields quickly resulted in advances that improved survivability, such as pressure dressings made with substances that cause blood to clot within seconds, a tourniquet that could be applied with one hand, and ways to ensure the supply of blood and blood products for transfusion despite disruptions of distance and climate.

A study by the U.S. Army Institute of Surgical Research found that nearly a quarter of the 4,596 U.S. combat-wound deaths in Iraq and Afghanistan between 2001 and 2011 were, as the report puts it, “potentially survivable.”

About 90 per cent of those survivable deaths were due to uncontrolled blood loss. Those findings started a quest to develop more tools to deal with massive blood loss from combat wounds.

Those tools need to work fast. Most battlefield deaths occur within 10 minutes of injury. An adult can die in minutes from massive blood loss such as that which accompanies wounds from improvised explosive devices. Significant and sudden blood loss can send the body into shock; when blood volume drops too low, the heart stops pumping and organs shut down. Nerve cells in the brain can survive only minutes without adequate blood flow.

About two thirds of blood-loss deaths in the U.S. study were from wounds to the trunk and underlying organs, where pressure could not be applied to stop bleeding. Two new types of tourniquet address the problem. Both can be applied in less than a minute on the battlefield. 

The Combat Ready Clamp can be used on areas of the body that standard tourniquets can’t reach. It roughly resembles the C clamp found in household tool boxes and is screwed tight in a similar way—very useful to stop bleeding from high leg amputations and pelvic injuries.

The Abdominal Aortic Junction Tourniquet is an inflatable wedge-shaped bladder that squeezes closed blood vessels, thus stopping bleeding from wounds. Its large surface area is useful for pelvic injuries and severe wounds in places where limbs attach to the torso.

The U.S. military has supported research into injectable and spray-on gels and foams that could plug wounds, stop bleeding and induce clotting.

Researchers at Johns Hopkins University in Baltimore, Maryland, have developed a prototype device to stop up wounds. About the size of a highlighter pen, it contains two chemicals that mix when injected into a wound, creating a foam that hardens and applies pressure to stop bleeding while soldiers are transported from the battlefield to hospital care.

Research continues to ensure it can produce enough foam to fill large wounds and harden quickly, and that the foam can be easily removed for surgery.

Meanwhile, the XStat Rapid Homeostasis System was battle- tested a year ago, stopping severe bleeding from a gunshot wound to the thigh of a U.S. soldier. The device looks like a large test tube with a plunger at the top. The tube is filled with nearly 100 tablet-shaped sponges that are injected into the wound and rapidly absorb blood and expand, plugging the wound and allowing clotting to begin.

A material that can be used to form an artificial blood clot has been developed by a research team from four high-powered U.S. research universities, supported in part by the U.S. Army Research Office.

Called shear-thinning biomaterial, it is a gel that can be injected by needle or catheter into blood vessels, where it solidifies to form a tight barrier, or can be applied to larger wound surfaces to halt bleeding. It is made up of gelatin and silicate nanoplatelets which mimic the function of platelets, the cells in human blood that promote blood clotting. Research is progressing from animal to human trials, so it will be some time before it’s available for battlefield medicine.

The U.S. military has also funded research at the Australian Institute of Health and Tropical Medicine at James Cook University on a drug touted as a “pharmacological tourniquet” that reduces internal blood loss by up to 60 per cent. 

Administered intravenously, a stabilizing fluid made of substances that regularize heart rhythm and blood pressure, among other things, “resuscitates the body from hemorrhagic shock,” said Dr. Geoffrey Dobson. “It…protects the body and stops the blood from thinning, allowing it to rapidly form a viable clot and reduce bleeding.” It provides medics “a new way to buy time on the battlefield,” he said.


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