Last reviewed: 23 Aug 2023
Last updated: 30 Aug 2022



History and exam

Key diagnostic factors

  • altered cognition/agitation
  • hypotension
More key diagnostic factors

Other diagnostic factors

  • tachypnea
  • tachycardia
  • prolonged capillary refill time
  • oliguria
  • muscle weakness
  • cyanosis
  • cool extremities
  • evidence of trauma
  • petechial rash
  • chest pain
  • fever
  • abdominal pain
  • jugular venous distention
  • peripheral edema
  • absent breath sounds on one side of chest
  • tracheal deviation
  • quiet heart sounds
  • flaccid paralysis of lower limbs
  • cardiac murmur
  • distended bladder
  • facial and tongue swelling
  • urticarial rash
  • pelvic pain/vaginal bleeding in woman of childbearing age
Other diagnostic factors

Risk factors

  • increasing age
  • comorbidities
  • myocardial infarction
  • cardiomyopathy
  • heart valve disease
  • arrhythmias
  • trauma
  • gastrointestinal bleeding
  • ruptured abdominal aortic aneurysm
  • burns/heat stroke
  • gastrointestinal losses: diarrhea and vomiting
  • pancreatitis
  • sepsis
  • anaphylaxis/poisoning
  • spinal or brainstem injury
  • endocrine disease
  • pulmonary embolism
  • cardiac tamponade
  • new medication (anaphylactic shock)
More risk factors

Diagnostic investigations

1st investigations to order

  • lactate (arterial blood gas)
  • blood gases
  • CBC
  • BUN and creatinine
  • serum electrolytes
  • coagulation studies (INR, activated PTT)
  • blood glucose
  • anion gap
  • CRP
  • procalcitonin
  • ECG
More 1st investigations to order

Investigations to consider

  • chest x-ray
  • focused assessment with sonography for trauma scan
  • echocardiography
  • end tidal carbon-dioxide (capnography)
  • ultrasound of thorax
  • ultrasound of abdomen
  • CT thorax, abdomen, and pelvis
  • computed tomographic pulmonary angiography
  • urinalysis and urine pregnancy test
  • pelvic ultrasound
  • x-ray long bones
  • x-ray spine
More investigations to consider

Treatment algorithm


all patients



Samuel J. Stratton, MD, MPH
Samuel J. Stratton


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.


Dr Samuel J. Stratton wishes to gratefully acknowledge Dr Christoph Pechlaner and Dr Christian Wiedermann, previous contributors to this topic.


CP and CW declare that they have no competing interests.

Peer reviewers

Patrick Nee, FRCP, FRCS, FCEM

Consultant in Accident & Emergency Medicine

St Helens & Knowsley Hospitals NHS Trust

Whiston Hospital




PN declares that he has no competing interests.

James Brown, MD, MMM

Vice-Chair and Program Director

Wright State University Department of Emergency Medicine




JB declares that he has no competing interests.

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