A new kind of inflatable tourniquet created by Dr. John Croushorn and materials experts will soon be in the hands of U.S. Army combat medics. It was named by Popular Science as one of the top 10 inventions of the year. (Photo credit Birmingham News.)
BIRMINGHAM, Alabama -- On Friday morning the U.S. Special Operations Command received its first shipment of a medical device that has Birmingham roots and promises to save lives on the battlefield.The Abdominal Aortic Tourniquet will be used when soldiers or Marines are injured in the pelvis or upper leg by gunshot, shrapnel or a blast, causing a wound that could bleed a person to death within minutes. A medic quickly straps the AAT around the belly of the victim, tightens it with a windlass and pumps in air.This pushes a balloon into the belly with the force of more than 80 pounds, clamping the abdominal aorta against the spine to cut off blood flow to the legs."The idea is you're turning off the faucet," said Dr. John Croushorn, one of the inventors. Croushorn is an emergency department doctor at Trinity Medical Center and a former U.S. Army surgeon, and his start-up company, Compression Works, is based in Hoover.Four plastic parts of the one-pound AAT are made by Innovative Composite Solutions, a UAB spinoff co-founded by Uday Vaidya, a UAB professor of mechanical engineering. ICS develops and makes high-strength thermoplastic composite components, and it won $100,000 in the 2009 Alabama Launchpad business plan competition sponsored by the Alabama Economic Development Partnership Foundation.The AAT "soldier saver" was picked as one of the top 10 inventions of the year in the June issue of Popular Science.Compression Works will ship 500 of the AATs by the end of June, and the device is getting further testing by the Army, Navy and the United Kingdom at the U.S. Army's Institute of Surgical Research in San Antonio, Texas.Croushorn filmed a training video in Hoover last month, using volunteers from metro-area police departments dressed as Army soldiers, with one wounded in the pelvic area and covered with Halloween-store fake blood. The video simulates a firefight, and Croushorn plays the Army medic who straps on the AAT and pumps it up in a minute and a half.Capability gapMilitary surgical interest is high, because the wounds called "pelvic-junctional hemorrhage" have been the number-one capability gap for the past five years. Terrorists seem to be aiming at that part of the body, which is unprotected by body armor.In the 1800s Joseph Lister created, and briefly used, a large C-clamp device called the Lister tourniquet to press on the belly to stop blood flow during leg amputations.U.S. military medics had been kneeling on the bellies of wounded men to mimic that clamping, Croushorn said. In 2006, a group of doctors at the Medical College of Georgia's emergency medical department decided to see how hard you had to push on the belly to stop the blood flow in the femoral artery of the leg.The volunteers were the doctors themselves. They put a tightly bundled pad about the size of a human knee on the belly, and then put dumbbells on it, starting at 20 pounds and increasing the weight by 20-pound increments to 140 pounds.Blood flow stopped at 80 pounds or above, with an average of 104 pounds of pressure.Croushorn and co-inventor Dr. Richard Schwartz, head of emergency medicine at the Georgia Health Sciences University, heard the dumbbell study at an emergency physicians meeting in New Orleans, and talked about making a device to simulate the dumbbell pressure.The first prototypes came in 2007, and the key step was a test on eight anesthetized pigs to see what happened if the prototype was left on for an hour, instead of just minutes for the human volunteers. This simulates the time needed to get the wounded soldier to a surgeon."We thought we were going to kill the pigs,'" Croushorn said, but the results were surprising -- no signs of dangerous changes in blood potassium or lactate levels, and no sign of damage to the small and large intestines.Their final device got quick approval by the FDA last year, and a potential order for 10,000 to 30,000 units is in the works.An even bigger market may be civilian EMS teams, Croushorn said. Dog experiments suggest that clamping the abdominal artery results in better chest compression results to push blood and oxygen to the brain. This could be vital for people who have suffered out-of-hospital cardiac arrests.