A sprayable polymeric foam hemostat for both compressible and non-compressible (intracavitary) acute wounds is disclosed. The foam comprises hydrophobically-modified polymers, such as hm-chitosan, or other amphiphilic polymers that anchor themselves within the membrane of cells in the vicinity of the wound. By rapidly expanding upon being released from a canister pressurized with liquefied gas propellant, the foam is able to enter injured body cavities and staunch bleeding. The seal created is strong enough to substantially prevent the loss of blood from these cavities. Hydrophobically-modified polymers inherently prevent microbial infections and are suitable for oxygen transfer required during normal wound metabolism. The amphiphilic polymers form solid gel networks with blood cells to create a physical clotting mechanism that prevent loss of blood.