“The device has a total absorption of approximately 30 times its initial weight within two minutes,” says Liping Sun, a senior scientist at Aurora. Depending on the size of the wound, multiple pouches can be used. Each one can swell to about the size of a couple of grapefruits, says de Luis. But ideally, a pouch would not expand all the way–only enough to stop the flow of blood. The pouch also works like a diaper: it locks in the fluid so that the blood can’t be squeezed out. Tests on pigs at MGH yielded promising results: all of the test subjects treated with the pouch survived their injuries, versus only 40 percent for the controls, which were tested with a standard army-issued gauze roll.
The swelling hemostat pouch could provide a good way to stop bleeding for a few hours, so that a soldier or a patient can be transported to a medical center, says Ali Khademhosseini, an assistant professor in the Harvard-MIT division of health sciences and technology, and a winner of the TR35. “Unlike similar devices, it works to minimize the amount of liquid that would come out of the wound,” says Khademhosseini.
Two other types of devices already used by the U.S. military are made by HemCon and Z-Medica. HemCon, based in Portland, OR, makes bandages from chitosan, a naturally occurring, biocompatible polysaccharide derived from shrimp shells. When applied to a wound, the positively charged chitosan attracts negatively charged blood cells, which seals the wound and allows the body to form a clot that stops hemorrhaging.
Z-Medica, based in Wallingford, CT, makes a pourable product called QuickClot that uses zeolite-based agents to soak up the blood and adhere to the tissue at and around the wound site.
But for traumatic injuries, one needs to have a fast system that can prevent bleeding in large wounds, says Khademhosseini. HemCon bandages, for example, only cover a four-by-four-inch area.
“The main benefit to our device is that it is purely a mechanical application, so we don’t have any complications with chemical reactions or exothermic reactions,” says de Luis.
Researchers at MIT, led by Rutledge Ellis-Behnke, are also working on an innovative solution: a biodegradable liquid that can quickly stop bleeding. (See “Nanosolution Halts Bleeding” and “TR10: Nanohealing.”) It could also be used to promote healing particularly for wounds inside the body. The biodegradable liquid is still three to five years from being approved for use in humans, however, and MIT researchers say that it will first be used in surgical procedures. Its impact on large wounds and in other areas is unknown.
According to de Luis and Velmahos, the swelling hemostat can be developed for less than $10 per pouch, and it could be on the battlefield within a year. “These kinds of things are very useful not just for the battlefield, but for biomedical treatment anywhere,” says Khademhosseini. “They use standard polymers that are cheap and commercially available.”