New Chitosan-Dressed Banage Stanches Battlefield Hemorrhage

Courtesy of Comprint Military Publications
Written by Karen Fleming-Michael
Published: February 21, 2003

Shrimp shells, of all things, may contain the military's solution to the problem of hemorrhage on the battlefield. More specifically, the shell's chitin, after it's transformed into a specific form of chitosan, forms a seal that can stop uncontrolled bleeding.

"There are lots of dressings that can stop small oozing or capillary bleeding, but that's not good enough because that's not what kills soldiers on the battlefield," said Dr. Anthony Pusateri, who's managed the Hemostasis Research Program since 1999 at the U.S. Army Institute of Surgical Research in San Antonio.

Since Operation Restore Hope in Somalia ended in 1993, Army researchers have been making strides toward making uncontrolled battlefield hemorrhage a distant, horrible memory. On modern battlefields, more than nine of 10 combat deaths occur before evacuation, and a little more than half of those are caused by uncontrolled hemorrhage, said Pusateri, a physiologist who's worked in hemorrhage control for nearly eight years.

"We need to keep casualties alive longer so we have more time to evacuate them for surgical treatment. When we can get them to surgeons, they almost always survive," he said. In studies performed at the institute in 2002, the chitosan dressing effectively stanched a wound that in the first 30 seconds put out more than 300 milliliters of blood.

Created by researchers at the Oregon Medical Laser Center using a research grant from the U.S. Army Medical Research and Materiel Command, the 4-inch by 4-inch chitosan dressing is well suited for the battlefield and a vast improvement over gauze and pressure bandages currently used to stop extreme bleeding, said Col. Bob Vandre, director of Combat Casualty Care research for the U.S. Army Medical Research and Materiel Command. The dressing's durability and flexibility make it "soldier proof," he said. The dressing can withstand blunt force as well as extreme field conditions, including inclement weather, temperature and rugged terrain.

"We haven't actually run over it with a HUMVEE, but it does stay together well, and that's an important factor because we need soldiers to be able to carry it in their packs and run around with it, fall down on it (without damaging it), et cetera" Pusateri said.

Further, chitosan is also antimicrobial, so it kills germs as a "nice freebie" for soldiers injured on dirty battlefields, Vandre said. The bandage poses no threat to people who are allergic to shrimp, he added. "It turns out that though many people are allergic to shrimp, they're not allergic to the chitin," he said.

Who will receive the bandage is an issue that's currently being discussed at the Army Medical Department Center and School. The current issue plan gives two bandages to the combat lifesaver and 10 to the medic, though Col. John Holcomb, MD, commander of the U.S. Army Institute of Surgical Research, thinks someday every soldier may carry one.

Because the dressing uses chitin, a natural polymer found in shrimp shells, as well as lobsters, crabs, insects, worms, fungus and mushrooms, Vandre said he hopes the bandage will be fairly inexpensive. "If the company that's producing the bandage can find a good source of chitin, the price could drop," he added.

For now, the Food and Drug Administration has approved the chitosan dressing for external use and the Army will use it on arm and leg, or extremity, wounds, which account for 10 percent of battlefield deaths. Holcomb, a combat surgeon in Somalia, witnessed that statistic firsthand while treating soldiers in Somalia who had pelvis and extremity wounds and died.

"With no other major injuries, I couldn't stop their bleeding. It was extremely frustrating," he said.

Recalling the scene in the movie "Blackhawk Down" where a soldier dies from a leg wound, Vandre said, "Although we don't know it for a fact, it appears this bandage can stop that kind of bleeding. The people who do pathology say they believe it can stop that kind of bleeding."

In fact, a hemostatic dressing like the chitosan dressing could have saved lives during Operation Enduring Freedom, according to Chris Kelly, public affairs officer at the Armed Forces Institute of Pathology, which performed autopsies on the first 30 servicemembers who died in Afghanistan.

"We found that with early, adequate treatment, hemostasis can reduce mortality," he said. "By looking at our autopsy findings, at least three cases could have been saved had we had a hemostatic dressing."

Researchers also believe hemostatic dressings can save limbs as well as lives because they limit the amount of time a tourniquet is needed. "You can't leave a tourniquet on for more than a few hours, or the loss of circulation in that limb will cause it to need to be amputated," Vandre said. "The thought with this dressing is that you can put on a tourniquet, stick the dressing on, stop the bleeding, then take the tourniquet off and keep circulation to the limb (so amputation isn't necessary)."

Researchers will take the dressing to the next level--internal use--this spring to see if the body can absorb the bandage.

"You go for external first because it's easiest to get through the FDA, and on the battlefield external is what medics do," Vandre said. "But on the battlefield and in emergency surgery, the first thing you try to do is stop bleeding. If you have a bandage you can put over a large bleeding area and stop bleeding, it would be nice to be able to leave it there ... and have the body resorb the bandage over time."

The Army's other hemostatic dressing, a fibrin bandage, is not out of the picture because of the chitosan one. Though the chitosan dressing is more durable and cheaper than the fibrin dressing, Vandre said he can envision the Army having both products for hemorrhage control.

"For internal use, it's not as clear which product will be the winner," he said. "We're not clear if it (the chitosan dressing) will resorb, and we're pretty sure the fibrin bandage will." Tests at the Institute of Surgical Research will help answer that question by summer, Holcomb said.

Having two promising dressings is a predicament researchers are thrilled to be in. "Before we started there were no advanced hemostatic dressings," Pusateri said. "Now companies from all over the place are coming up with new ideas."

The chitosan bandages should be available in the near future, Vandre said. The U.S. Army Medical Research and Materiel Command and the U.S. Army Special Operations Command chipped in for the Oregon Medical Laser Center's manufacturer, Hemcon, to make 5,000 bandages. Congress appropriated $2.8 million for 20,000 bandages that will be available to all the services through Department of Defense supply channels.

Vandre said the bandages are coming none too soon and will be invaluable on future battlefields. "If there's a way to stop the bleeding faster, it will save lives," he said.