Last reviewed: 30 Dec 2022
Last updated: 14 Oct 2022



History and exam

Key diagnostic factors

  • hypotension
  • tachycardia
  • skin changes
  • oliguria
  • mental state changes
  • presence of risk factors
  • fever
  • chest pain
  • dyspnoea
  • hypoxaemia
  • hypothermia
Full details

Other diagnostic factors

  • abdominal pain
  • peripheral oedema
  • raised jugular venous pressure (JVP)
  • muffled or quiet heart sounds
  • arrhythmia
  • petechial rash
  • urticarial rash
  • angio-oedema
  • reduced breath sounds on one side of the chest
  • tracheal deviation
  • distended bladder
  • flaccid paralysis of the limbs
Full details

Risk factors

  • increasing age
  • comorbidities
  • myocardial infarction
  • cardiomyopathy
  • heart valve disease
  • arrhythmias
  • trauma
  • gastrointestinal bleeding
  • ruptured abdominal aortic aneurysm
  • burns/heat stroke
  • gastrointestinal losses: diarrhoea and vomiting
  • pancreatitis
  • sepsis
  • anaphylaxis/poisoning
  • spinal or brainstem injury
  • endocrine disease
  • pulmonary embolism
  • cardiac tamponade
  • medication induced
Full details

Diagnostic investigations

1st investigations to order

  • lactate (from arterial blood gas)
  • venous blood gas (VBG) or arterial blood gas (ABG)
  • glucose
  • full blood count
  • urea and electrolytes
  • coagulation studies
  • C-reactive protein
  • procalcitonin
  • ECG
Full details

Investigations to consider

  • chest x-ray
  • urinalysis and urine pregnancy test
  • infection screen
  • point-of-care ultrasound
  • CT chest, abdomen, and pelvis
  • computed tomographic pulmonary angiography (CTPA)
  • x-ray long bones
  • x-ray spine
Full details

Treatment algorithm


all patients


Expert advisers

Alexander Alexiou, MBBS, BSc, DCH, FRCEM, Dip IMC RCSEd

Emergency Medicine Consultant

Barts Health NHS Trust

Physician Response Unit Consultant

London’s Air Ambulance

Royal London Hospital



AA declares that he has no competing interests.

Clovis Rau, MBBS, BSc, FRCEM DipIMC

ST6 Emergency Medicine

Barnet Hospital

Royal Free NHS Foundation Trust



CR declares that he has no competing interests.


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

Samuel J. Stratton MD, MPH


Fielding School of Public Health

David Geffen School of Medicine at UCLA

Los Angeles

Deputy Health Officer

Orange County Health Care Agency

Health Disaster Management/Emergency Medical Services

Santa Ana



SJS declares that he has no competing interests.

Peer reviewers

Paul Frost

Reader (clinical)

Centre for Medical Education

School of Medicine

Cardiff University

Honorary Consultant in Intensive Care Medicine

University Hospital of Wales




PF declares that he has no competing interests.

Michael Toolis, MBBS, FCICM, GDipClinUS

Consultant Intensivist

Monash Health




MT declares that he has no competing interests.


Annabel Sidwell

Section Editor, BMJ Best Practice


AS declares that she has no competing interests.

Tannaz Aliabadi-Oglesby

Lead Section Editor, BMJ Best Practice


TAO declares that she has no competing interests.

Luisa Dillner

Head of Research and Development, BMJ


Julie Costello

Comorbidities Editor, BMJ Best Practice


JC declares that she has no competing interests.

Adam Mitchell

Drug Editor, BMJ Best Practice


AM declares that he has no competing interests.

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