Pathophysiology of cold exposure.

The change in core temperature that occurs as a result of exposure to cold air or water affects all body systems. A decrease in core temperature induces shivering, then muscle stiffness; depresses the central nervous and respiratory systems; triggers cardiac arrhythmias and vasoconstriction; and affects body [figure: see text] fluid balance. Cold water immersion presents additional considerations, including the general shock effect on the cardiac and respiratory systems and the triggering of the diving reflex when the entire body is immersed. Basic education and precautions can prevent most cases [figure: see text] of accidental hypothermia; but when they do occur, treatment should include controlled rewarming, especially if the core temperature is below 32 degrees C.