Hypothermia is defined by a core body temperature <95°F (<35°C).
Classified as mild, moderate, or severe according to clinical features.
Core temperature measured in the lower third of the esophagus correlates well with pulmonary artery temperature and is preferred in patients with a secure airway. A low-reading tympanic thermistor-based thermometer is a less invasive alternative.
Initial management should focus on stopping further cooling. This includes removing the patient from the cold environment, careful removal of wet or cold clothing, insulation, warming the body, securing the airway, monitoring breathing and circulation, and maintaining circulation using warm intravenous fluids.
Patients who have sustained a hypothermic cardiac arrest should ideally be rewarmed in a specialist center using Extracorporeal Life Support. Management strategies and criteria for termination of resuscitation in hypothermic cardiac arrest must not be extrapolated from those used in normothermic arrest.
Accidental hypothermia is characterized by the unintentional lowering of core body temperature below physiologic normal limits, typically <95°F (<35°C).
A threshold of 96.8°F (36°C) has been adopted in patients with trauma. In this patient group, even milder degrees of hypothermia have devastating consequences in both military and civilian populations.
History and exam
Key diagnostic factors
- cold exposure and body temperature <95°F (<35°C)
- impaired mental state
Other diagnostic factors
- tachypnea, tachycardia, hypertension if mild hypothermia
- respiratory depression, bradycardia, hypotension if moderate hypothermia
- coma and apnea if severe hypothermia
- cold-induced diuresis
- general anesthetic use
- substance abuse
- impaired mental status
- Parkinson disease
- neuroleptic medication
- beta-blocker medication
- sedative hypnotic medication
- older age
- infants and young children
- gram-negative septicemia
1st investigations to order
- core temperature measurement
- 12-lead ECG
- serum electrolytes
- blood glucose
- coagulation factors
- chest x-ray
mild hypothermia: >90°F to 95°F (>32°C to 35°C)
moderate or severe hypothermia: ≤90°F (≤32°C)
moderate or severe hypothermia in cardiac arrest: ≤90°F (≤32°C)
- European Resuscitation Council Guidelines 2021: Cardiac arrest in special circumstances
- 2020 American Heart Association Guidelines for Cardiopulmonary Resuscitation and Emergency Cardiovascular Care: Adult Basic and Advanced Life Support
- Log in or subscribe to access all of BMJ Best Practice
Use of this content is subject to our disclaimer