Last reviewed: 4 Feb 2021
Last updated: 07 Jan 2021

Summary

Definition

History and exam

Key diagnostic factors

  • history of exposure to severe environmental heat or strenuous physical exercise
  • central nervous system dysfunction
  • hyperthermia (>40°C) 
  • anhidrosis
  • risk factors 

Other diagnostic factors

  • intense thirst (heat stroke or heat exhaustion) 
  • weakness (heat stroke or heat exhaustion)
  • anxiety (heat stroke or heat exhaustion)
  • dizziness (heat stroke or heat exhaustion)
  • syncope (heat stroke or heat exhaustion)
  • headache (heat stroke or heat exhaustion)
  • nausea/vomiting (heat stroke or heat exhaustion)
  • sinus tachycardia
  • tachypnoea
  • jaundice
  • muscle tenderness
  • hypotension
  • bruising and skin bleeding

Risk factors

  • older age
  • impaired cognition
  • patients unable to care for themselves
  • medicines
  • lack of acclimatisation to hot environments
  • pre-existing dehydration
  • obesity
  • poor physical condition
  • environmental factors
  • young, active people exercising intensely under hot, humid conditions

Diagnostic investigations

1st investigations to order

  • rectal temperature
  • FBC
  • liver function tests
  • renal function tests
  • glucose
  • electrolytes
  • arterial blood gases
  • creatine kinase
  • clotting profile
  • urinalysis
  • ECG

Treatment algorithm

Contributors

Expert advisersVIEW ALL

Flight Doctor

Greater Sydney Area Helicopter Emergency Medical Service

Sydney

New South Wales

Australia

Disclosures

AA declares that he has no competing interests.

BMJ Best Practice would like to gratefully acknowledge the previous expert contributor, whose work is retained in parts of the content:

James L. Glazer, MD, FACSM, CAQSM

Assistant Professor

Tufts University School of Medicine

Boston

MA

Peer reviewersVIEW ALL

Consultant in Emergency Medicine

Barnet Hospital

Royal Free London

London

UK

Disclosures

HS declares that she has no competing interests.

Section Editor, BMJ Best Practice

Disclosures

HDC declares that she has no competing interests.

Lead Section Editor, BMJ Best Practice

Disclosures

TAO declares that she has no competing interests.

Lead Section Editor, BMJ Best Practice

Disclosures

RW declares that she has no competing interests.

Comorbidities Editor, BMJ Best Practice

Disclosures

AS declares that she has no competing interests.

Drug Editor, BMJ Best Practice

Disclosures

AM declares that he has no competing interests.

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