August 12, 2022
Hypothermia is the reduced body temperature that occurs when a body dissipates more heat than it produces internally for a sufficiently long time. In humans, it is defined as a standard body temperature below 35.0 °C (95.0 °F). Symptoms depend on temperature. In mild hypothermia there may be chills to mental confusion. In moderate hypothermia, shaky stops and mental confusion increase. In severe hypothermia, there can be paradoxical undressing, in which a person removes their clothing, as well as a risk of cardiac arrest. Hypothermia has two main types of causes. It usually occurs from exposure to extreme cold. It can also occur from any condition that decreases heat production or increases heat loss. Commonly this includes alcohol intoxication, but it can also include low blood sugar levels, anorexia, old age among others. Body temperature is generally maintained near a constant level of 36.5–37.5 °C (97.7–99.5 °F) through thermoregulation. Efforts to increase body temperature involve shivering, increased voluntary activity, and wearing warmer clothing. Hypothermia can be diagnosed based on a person's symptoms in the presence of risk factors or by measuring a person's body temperature. Treatment for mild hypothermia involves hot drinks, warm clothing, and physical activity. In those with moderate hypothermia, blankets and warm intravenous fluids are recommended. People with moderate or severe hypothermia should be moved gently. In severe hypothermia, extracorporeal membrane oxygenation (ECMO) or cardiopulmonary massage may be helpful. In those who do not have an arterial pulse, cardiopulmonary resuscitation (CPR) is indicated along with the above measures. Rewarming is typically continued until a person's temperature is greater than 32 °C (90 °F). If at this point there is no sign of improvement or the blood potassium level is greater than 12 mmol/liter, resuscitation can be discontinued. Hypothermia is the cause of at least 1,500 deaths per year in the United States. It is more common in older people and men. One of the lowest documented body temperatures that someone with accidental hypothermia has survived is 13 °C (55.4 °F) in a near-drowning of a 7-year-old girl in Sweden. Deaths due to hypothermia have played an important role. in many wars. Hyperthermia is the opposite of hypothermia, being an increased body temperature due to failed thermoregulation. The term is from the Greek ὑπο, ypo, meaning "from below", and θερμία, thermía, meaning "heat".