If US troops have to go into battle in Iraq in the next few months, army medics could be carrying a new bandage that can stop hemorrhaging better than conventional gauze dressings.
The need for a new bandage is pressing; approximately 90% of combat deaths occur prior to hospitalization. Not surprisingly, hemorrhaging is the single most frequent cause of death. But given the high tech nature of the modern battlefield, what is surprising is that field medics have basically the same tools—namely gauze dressings—to stop bleeding that they had 100 years ago.
With a small grant from the army, a group of Portland, Oregon researchers set out to create a new bandage. After experimenting with a number of materials, they finally settled on the biopolymer, chitosan, because it has a good mix of the biological and chemical properties they were looking for in a bandage. This “chitosan” bandage recently won limited FDA approval.
What is Chitosan?
Chitosan is a high molecular weight polymer derived from a natural product, chitin, found in the shells of shrimp, crabs, and a host of other animals. Chitin is a biodegradable polysaccharide that is similar to cellulose. Like cellulose, chitin and its derivative chitosan are fibrous materials. Chitosan is made from chitin by removing acetyl groups (CH3-CO) from the chitin polymer chain with dilute acids. By controlling the number of acetyl groups removed along the chain (or by adding new groups to sites that once had an acetyl group), chemists can tune the properties of chitosan to make it more versatile.
Primarily, the new bandage exploits a fortuitous property of chitosan; namely, when chitosan comes in contact with blood, it induces clotting. Using a modified form of chitosan, the researchers developed a durable and flexible field dressing that sticks to and seals wounds. As an added benefit, the chitosan also has antimicrobial properties.
Coming to an ambulance near you?
Similar to injury on the battlefield, trauma caused by an accident can cause a person to bleed to death in minutes. If these bandages perform well in the field, it is likely that civilian first-responders will want to start carrying the chitosan bandages.
For now, only the military can use the bandages and only on extremities, but the manufacturer of the new dressing, HemCon, Inc, is confident that it can win FDA approval for a multitude of uses, including a possible use for internal injuries.
This article first appeared March 3, 2003.