Hypothermia

Hypothermia
Napoleons retreat from moscow.jpg
During Napoleon Bonaparte's retreat from Russia in the winter of 1812, many troops died from hypothermia. [1]
Specialty Critical care medicine
Symptoms Mild: Shivering, mental confusion [2]
Moderate: No shivering, increased confusion [2]
Severe: Paradoxical undressing, cardiac arrest [2]
Risk factors Alcohol intoxication, low blood sugar, anorexia, advanced age [1] [2]
Diagnostic method Based on symptoms or body temperature below 35.0 °C (95.0 °F) [2]
Treatment Mild: Warm drinks, warm clothing, physical activity [2]
Moderate: Heating blankets, warmed intravenous fluid [2]
Severe: Cardiopulmonary resuscitation, extracorporeal membrane oxygenation, cardiopulmonary bypass [2]
Deaths 1,500 per year (US) [2]

Hypothermia is reduced body temperature that happens when a body dissipates more heat than it absorbs. In humans, it is defined as a body core temperature below 35.0 °C (95.0 °F). Symptoms depend on the temperature. In mild hypothermia there is shivering and mental confusion. In moderate hypothermia shivering stops and confusion increases. In severe hypothermia, there may be paradoxical undressing, in which a person removes his or her clothing, as well as an increased risk of the heart stopping. [2]

Hypothermia has two main types of causes. It classically occurs from exposure to extreme cold. [1] It may also occur from any condition that decreases heat production or increases heat loss. [1] Commonly this includes alcohol intoxication but may also include low blood sugar, anorexia, and advanced age. [1] [2] Body temperature is usually maintained near a constant level of 36.5–37.5 °C (97.7–99.5 °F) through thermoregulation. [2] Efforts to increase body temperature involve shivering, increased voluntary activity, and putting on warmer clothing. [2] [3] Hypothermia may be diagnosed based on either a person's symptoms in the presence of risk factors or by measuring a person's core temperature. [2]

The treatment of mild hypothermia involves warm drinks, warm clothing, and physical activity. In those with moderate hypothermia, heating blankets and warmed intravenous fluids are recommended. People with moderate or severe hypothermia should be moved gently. In severe hypothermia, extracorporeal membrane oxygenation (ECMO) or cardiopulmonary bypass may be useful. In those without a 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 there is no improvement at this point or the blood potassium level is greater than 12 mmol/liter at any time, resuscitation may be discontinued. [2]

Hypothermia is the cause of at least 1,500 deaths a year in the United States. [2] It is more common in older people and males. [4] One of the lowest documented body temperatures from which someone with accidental hypothermia has survived is 13.0 °C (55.4 °F) in a near-drowning of a 7-year-old girl in Sweden. [5] Survival after more than six hours of CPR has been described. [2] For those for whom ECMO or bypass is used, survival is around 50%. [2] Deaths due to hypothermia have played an important role in many wars. [1] The term is from Greek ὑπο, ypo, meaning "under", and θερμία, thermía, meaning "heat". The opposite of hypothermia is hyperthermia, an increased body temperature due to failed thermoregulation. [6] [7]

Classification

Hypothermia is often defined as any body temperature below 35.0 °C (95.0 °F). [8] With this method it is divided into degrees of severity based on the core temperature. [8]

Another classification system, the Swiss staging system, divides hypothermia based on the presenting symptoms which is preferred when it is not possible to determine an accurate core temperature. [2]

Other cold-related injuries that can be present either alone or in combination with hypothermia include:

  • Chilblains: superficial ulcers of the skin that occur when a predisposed individual is repeatedly exposed to cold [9]
  • Frostbite: the freezing and destruction of tissue [9]
  • Frostnip: a superficial cooling of tissues without cellular destruction [10]
  • Trench foot or immersion foot: a condition caused by repetitive exposure to water at non-freezing temperatures [9]

The normal human body temperature is often stated as 36.5–37.5 °C (97.7–99.5 °F). [11] Hyperthermia and fever, are defined as a temperature of greater than 37.5–38.3 °C (99.5–100.9 °F). [7]

Other Languages
Afrikaans: Hipotermie
azərbaycanca: Hipotermiya
беларуская: Гіпатэрмія
беларуская (тарашкевіца)‎: Пераахаладжэньне
български: Хипотермия
català: Hipotèrmia
čeština: Podchlazení
dansk: Hypotermi
Deutsch: Hypothermie
Ελληνικά: Υποθερμία
español: Hipotermia
Esperanto: Hipotermio
euskara: Hipotermia
فارسی: هیپوترمی
français: Hypothermie
Gaeilge: Hipiteirme
한국어: 저체온증
Հայերեն: Հիպոթերմիա
Bahasa Indonesia: Hipotermia
italiano: Ipotermia
עברית: היפותרמיה
қазақша: Ағза тоңазуы
latviešu: Hipotermija
lietuvių: Hipotermija
magyar: Hipotermia
Nederlands: Hypothermie
日本語: 低体温症
norsk: Hypotermi
ଓଡ଼ିଆ: ଅଳ୍ପତାପ
ਪੰਜਾਬੀ: ਹਾਈਪੋਥਰਮੀਆ
polski: Hipotermia
português: Hipotermia
română: Hipotermie
русский: Гипотермия
Simple English: Hypothermia
slovenčina: Hypotermia
slovenščina: Hipotermija
suomi: Hypotermia
svenska: Hypotermi
Türkçe: Hipotermi
українська: Гіпотермія
中文: 失溫症