When soldiers are wounded in battle, getting the bleeding under control is one of the most important life-saving measures medics can take. Due to the particular demands of doctoring in the field, however, this can be a significant challenge. A new injectable hydrogel that is activated by the body's own temperature may offer a way forward.
Hydrogels – chains of molecules that can store significant amounts of water – are something of a modern wonder material. Experiments have shown that they can function as armor, pull drinking water out of thin air, and act as window coatings that keep buildings cooler. Because of their high water content, they are also often used in the medical field, handling such tasks as plumping up damaged vertebral discs and making better brain implants. They've been widely studied as bandages too, employing proteins to kill bacteria at wound sites, helping seal up incisions in the digestive tract, and even bonding to wet skin through the use of ultrasound.
Up til now though, according to researchers at the Los Angeles-based Tarasaki Institute, hydrogel bandages have not been able to provide "fast, temperature-sensitive treatment of hemorrhage in a controllable manner." To remedy that situation, the researchers mixed a blood-coagulant with a temperature-sensitive polymer called poly(N-isopropyl acrylamide).
They then conducted two experiments. In one, they simulated blood flow using a series of syringes and tubes kept at the same temperature as human blood in the body, and then created "wounds" in the tube. In another, they nicked the livers of mice to cause bleeding. In both cases, the hydrogel became a solid once exposed to the wound sites (whether real or simulated) and was highly successful in stemming the flow of blood. What's more, the gel could be easily removed using a cold saline wash that didn't cause the bleeding to resume.
According to an analysis of battlefield wounds between 2001 and 2011, 87.3% of all battlefield deaths occurred before soldiers could reach a medical treatment facility, and of the potentially survivable injuries, 90.9% of the victims died of hemorrhage. So an easy-to-administer, effective solution that can stop bleeding could clearly have an impact on soldier mortality.
Further adding to the potential of the new material, say the researchers, is the fact that it satisfies the requirements for battlefield hemorrhage control, which are: "(1) quick and adequate hemostasis in a wide range of injuries and wounds, (2) sustained hemostasis for several hours in situations of delayed evacuation, (3) easy removal without leaving any residues in the injury or wound, (4) ready to use and easy administration by a layperson with little to no training, (5) easy to manufacture and sterilize with low costs, (6) easily stored with prolonged stability even under extreme climate conditions, and (7) good biocompatibility with no adverse effects."
The researchers also point out that the hydrogel can be used to treat any wounds – not just those sustained during battle – and that it could also be impregnated with drugs or other materials to enhance healing.
The research has been published in the journal, Biomaterials Science.
Source: Terasaki Institute