injuries poisoning
Nonfreezing Tissue Injuries
Immersion (trench) foot
Prolonged exposure to wet cold can cause immersion foot. Peripheral nerves and the vasculature are usually injured; muscle and skin tissue may be injured in severe cases. Initially, the foot is pale, edematous, clammy, cold, and numb. Tissue maceration may occur if patients walk extensively. Rewarming causes hyperemia, pain, and often hypersensitivity to light touch, which can persist for 6 to 10 weeks. Skin may ulcerate, or a black eschar may develop. Autonomic dysfunction is common, with increased or decreased sweating, vasomotor changes, and local hypersensitivity to temperature change. Muscle atrophy and dysesthesia or anesthesia may occur and become chronic. Immersion foot can be prevented by not wearing tight-fitting boots, keeping feet and boots dry, and changing socks frequently. may be tried (see Treatment ). 