When a soldier is shot in battle, it is rarely the case that the bullet leads to a quick and immediate death. Rather, the leading cause of death on the battlefield is hemorrhage, or excessive blood loss. While methods of clotting blood flow such as tourniquets or gauze pads do exist, they often do little to help in situations where a deep wound has been inflicted in junctional areas- such as the neck, shoulder, or groin. As a result, casualties due to blood loss often occur while soldiers are being transported to a nearby medical station or hospital.
In 2013, students at John Hopkins University developed an injectable foam with hemostatic effects that could be applied to major wounds. The foam, a product of a chemical reaction between a polyol and a diisocyanate, expands exponentially once it is injected into a wound, then hardens a few seconds later to apply pressure to the walls of the cavity.
Although touted at that time as an innovative technology to quickly block blood loss on the battlefield, it was later discovered that the high blood pressure of soldiers would lead to the foam being washed right out- rendering the whole process useless in terms of preventing hemorrhage.
Now, an Oregon startup biotech company claims they have a better solution- a modified syringe containing small sponges that are injected directly into the wound. The sponges are coated with chitosan, a chemically processed form of chitin.
While chitosan has mainly been employed in biopesticides or drug transmission, scientists have recently discovered that it has hemostatic properties. The interaction of its positively charged amino side group with the negatively charged cell membrane of red blood cells leads to the accumulation of clotting factors, resulting in rapid thrombus formation.
When these sponges are directly injected into the open wound, they can expand up to 20 times their original size, applying pressure to the walls of the cavity in just 15 seconds. And because sponges naturally cling to moist surfaces, they aren’t washed right out by the flow of blood.