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The Defense Department is working to develop a high-tech ultrasonic tourniquet that would stop bleeding on the battlefield while keeping circulation flowing to the affected limb, lessening the possibility of amputations. Developers envision a cuff that could be placed around the bleeding arm or leg artery. Low-intensity ultrasonic waves would first detect the bleeding, then high-instensity ultrasonic waves would heat the rupture, causing it to clot.
The Defense Department is working to develop a high-tech ultrasonic tourniquet that would stop bleeding on the battlefield while keeping circulation flowing to the affected limb, lessening the possibility of amputations. Developers envision a cuff that could be placed around the bleeding arm or leg artery. Low-intensity ultrasonic waves would first detect the bleeding, then high-instensity ultrasonic waves would heat the rupture, causing it to clot. (Courtesy of Defense Advance Research Projects Agency)

After four deployments to the battlefield since 2002, Dr. Stephen Flaherty, an Army colonel, knows something about big bleeds and how little time there is to stop major bleeding from a casualty’s arteries.

Injuries to the extremities are all too common in Iraq and Afghanistan, Flaherty said, and time is of the essence if those major arteries are ruptured.

“If an artery was severed high in the leg or the upper arm, bleeding could result in death in just a matter of minutes,” said Flaherty, director of the trauma program at Landstuhl Regional Medical Center in Germany.

Tourniquets are the common medical answer to stanch bleeding arteries in the arms or legs, and have saved numerous lives downrange, he said.

But it’s not a perfect system. When a tourniquet is applied with enough pressure to stop the bleeding artery, it also impedes other blood flow to the limb beneath and can damage tissue.

And if the tourniquet isn’t removed in about an hour, toxins will build up in the limb at such a level that amputation becomes necessary, Flaherty said.

To those in the medical community, the choice is clear: lose the limb, save the life.

But a device is being developed that could one day stop extreme battlefield bleeding without the possibility of amputation.

Developers at the Defense Department call it “deep bleeder acoustic coagulation” system. In English, it’s an ultrasonic tourniquet.

The Defense Advance Research Projects Agency (DARPA) is working to develop cuffs that would use ultrasonic waves to locate the bleeding artery and then heat it to clot the blood.

The program is in the first of three phases, and prototypes are being built, said Tom McCreery, the DARPA program manager who came up with the idea.

“It should have less of an impact than a conventional tourniquet,” McCreery said. “A conventional tourniquet stops all blood flow to the limb. It would be a really selective tourniquet.”

McCreery said it would be ideal for combat zone medicine because it could get a casualty out while keeping the limb healthy.

“We’re not saying you’re going to charge back right into your mission,” he said. “It is designed for self-aid and buddy-aid.”

He envisions a device that would be as simple to use as the defibrillators found in gyms.

“The instructions are very much designed for the layperson,” he said. “The software finds the bleeder and does the treatment. A green light comes on and tells the soldier it’s done.”

The initiative, with funding of about $18 million for the first phase, could cost about $54 million by the end of phase three, said Monica Valdiviez-Wiley, a DARPA spokeswoman.

It is hoped that an initial backpack-size prototype can be in the hands of the military by late 2010, McCreery said. To speed up the process, the U.S. Food and Drug Administration is already involved, because that agency must approve anything used to treat servicemembers. There also are companies in the private sector working on the device, looking at possible commercial applications.

The process of using ultrasonic waves for such a treatment has been known for about 10 years, said Dr. Lawrence Crum, one of the inventors of the process and the head of the Center for Industrial and Medical Ultrasound at the University of Washington.

The main challenge in developing the ultrasonic tourniquet, he said, is finding a way to shrink the process down and make it usable.

“We are able now in our laboratory to detect, localize and stop bleeding in large animal models,” he said in an e-mail.

“However, this is done by a highly skilled user. Transferring the established scientific principles into a lightweight product that requires little training is the biggest challenge.”

Perfecting the process, so that the ultrasonic waves don’t accidentally hit a nerve right near the vessel, is another challenge, McCreery said.

But the science is there, he said. Developers just have to figure out how to make it user-friendly.

“There’s already experiments done, we know ultrasounds can find the bleeding and stop the bleeding,” he said. “We want to make it accessible for any soldier to treat his buddy.”

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