Hypothermia Core body temperature below 95°F (35°C) Usually due to environmental exposure Increased risk in very young and very old, thin individuals, males (due to decreased subcutaneous fat) Cold water exposure more rapidly fatal than cold air exposure, because water rapidly dissipates heat Physiological response to cold exposure: Superficial vasoconstriction Shivering Increased cellular metabolism (to produce heat); more efficient in infants due to "brown fat" When compensatory mechanisms fail, body temperature falls linearly Autopsy findings: No specific findings in hypothermia; it is a diagnosis of exclusion Cherry red lividity: due to accumulation of oxyhemoglobin in tissues; nonspecific (also seen in CO poisoning) If individual survives for a period of time, may show hemorrhagic pancreatitis, mucosal ulceration of GI tract, pneumonia, acute tubular necrosis, cardiomyocyte necrosis Paradoxical undressing: terminal hallucinations lead the individual to feel overheated despite the cold environment, causing them to undress Hyperthermia Core body temperature above 105°F (40.5°C) Heat stroke is severe form Occurs when body's mechanisms of dissipating heat are overwhelmed Risk factors: alcoholism, atherosclerosis, obesity, certain drugs (tricyclic antidepressants, some tranquilizers, monoamine oxidase inhibitors) Symptoms: hyperthermia, hot and dry skin, CNS dysfunction Vasodilation occurs, leading to circulatory failure If individual survives for a period of time, may develop pneumonia, acute tubular necrosis, adrenal hemorrhage, liver and myocardial necrosis, and DIC Autopsy findings: nonspecific; diagnosis is made based on scene investigation and antemortem signs and symptoms More mild forms include heat cramps and heat exhaustion: Heat cramps: due to salt depletion; skin is moist and cool, body temperature is normal Heat exhaustion: due to salt and water depletion; headache, nausea / vomiting, dizziness, weakness, cramps; body temperature is normal or slightly elevated Source
