Elsevier

Autonomic Neuroscience

Volume 196, April 2016, Pages 91-104
Autonomic Neuroscience

Review
Thermoregulatory disorders and illness related to heat and cold stress

https://doi.org/10.1016/j.autneu.2016.01.001Get rights and content
Under a Creative Commons license
open access

Highlights

  • Hypothermia (core temperature < 35.0 °C) and hyperthermia (core temperature > 40.5 °C) are medical emergencies.

  • Severely hypothermic patients are at risk of cardiac arrhythmias, including atrial and ventricular fibrillation.

  • The clinical feature that best differentiates heat stroke from heat exhaustion is a change in mental status.

  • Anhidrosis may be present in classical, but usually not in exertional, heat stroke. Sweating does not exclude heat stroke.

  • Ice water immersion for heat stroke should begin as early as possible to lower core temperature within 30 minutes

Abstract

Thermoregulation is a vital function of the autonomic nervous system in response to cold and heat stress. Thermoregulatory physiology sustains health by keeping body core temperature within a degree or two of 37 °C, which enables normal cellular function. Heat production and dissipation are dependent on a coordinated set of autonomic responses. The clinical detection of thermoregulatory impairment provides important diagnostic and localizing information in the evaluation of disorders that impair thermoregulatory pathways, including autonomic neuropathies and ganglionopathies. Failure of neural thermoregulatory mechanisms or exposure to extreme or sustained temperatures that overwhelm the body's thermoregulatory capacity can also result in potentially life-threatening departures from normothermia. Hypothermia, defined as a core temperature of < 35.0 °C, may present with shivering, respiratory depression, cardiac dysrhythmias, impaired mental function, mydriasis, hypotension, and muscle dysfunction, which can progress to cardiac arrest or coma. Management includes warming measures, hydration, and cardiovascular support. Deaths from hypothermia are twice as frequent as deaths from hyperthermia. Hyperthermia, defined as a core temperature of > 40.5 °C, may present with sweating, flushing, tachycardia, fatigue, lightheadedness, headache, and paresthesia, progressing to weakness, muscle cramps, oliguria, nausea, agitation, hypotension, syncope, confusion, delirium, seizures, and coma. Mental status changes and core temperature distinguish potentially fatal heat stroke from heat exhaustion. Management requires the immediate reduction of core temperature. Ice water immersion has been shown to be superior to alternative cooling measures. Avoidance of thermal risk and early recognition of cold or heat stress are the cornerstones of preventive therapy.

Keywords

Thermoregulation
Heat stroke
Heat exhaustion
Hypothermia
Rewarming
Hypohidrosis
Small fiber neuropathy

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