Enzymatic frostbite eschar debridement by bromelain.

Bromelain is a plant proteinase derived from the stem of the pineapple plant that has been used successfully to debride the eschar from third-degree burn injuries. Its applicability to frostbite eschar removal was extrapolated and investigated. Third-degree frostbite lesions were produced on swine using supercooled air as the freezing media, and the resulting eschars were treated with a bromelain preparation. In the initial trial, no debridement other than that of the superficial layers of the eschar was noted. The experiment then was repeated with the introduction of third-degree burn injuries as a control to validate the efficacy of the enzyme preparation. Although the burn injuries debrided to a graftable bed after two applications of the enzyme, the frostbite injuries remained unaffected. It was concluded that the patent vasculature, resulting tissue edema, and lack of coagulation of proteins found in the freeze injury are sufficient to inactivate the bromelain enzyme before tissue digestion and dissection can be effected.