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]
SpecialtyCritical care medicine
Symptoms
Risk factorsAlcohol intoxication, low blood sugar, anorexia, advanced age[1][2]
Diagnostic methodBased on symptoms or body temperature below 35.0 °C (95.0 °F)[2]
Treatment
Deaths1,500 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).[2] Symptoms depend on the temperature.[2] In mild hypothermia there is shivering and mental confusion.[2] In moderate hypothermia shivering stops and confusion increases.[2] 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.[2] In those with moderate hypothermia, heating blankets and warmed intravenous fluids are recommended.[2] People with moderate or severe hypothermia should be moved gently.[2] In severe hypothermia, extracorporeal membrane oxygenation (ECMO) or cardiopulmonary bypass may be useful.[2] In those without a pulse, cardiopulmonary resuscitation (CPR) is indicated along with the above measures.[2] Rewarming is typically continued until a person's temperature is greater than 32 °C (90 °F).[2] 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
Cymraeg: Hypothermia
dansk: Hypotermi
davvisámegiella: Hypotermiija
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
Bahasa Melayu: 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