Causes and categories of shock
The ANZCOR guideline classifies shock by underlying cause. This classification is useful for your own understanding but remember it is not a teaching focus for learners. The causes of shock are:
- Loss of circulating blood volume (hypovolemic shock), for example from:
- severe bleeding (internal and/or external)
- major or multiple fractures or major trauma
- severe burns or scalds
- severe diarrhoea and vomiting
- severe sweating and dehydration
- Cardiac causes (cardiogenic shock), for example from:
- heart attack
- abnormal heart rhythm
- weak heart muscle (cardiomyopathy)
- Abnormal dilation of blood vessels (distributive shock), for example from:
- severe infection with organ dysfunction (sepsis)
- severe allergic reactions (anaphylaxis)
- severe brain / spinal injuries
- fainting (generally brief)
- Blockage of blood flow in or out of the heart (obstructive shock), for example from:
- punctured lung, causing increased pressure in the chest and reducing return of blood to the heart (tension pneumothorax)
- blood around the heart reducing blood return to the heart (cardiac tamponade)
- blood clot in the lung (pulmonary embolus)
- compression of the large abdominal veins by the uterus in pregnancy
As a trainer you should know the categories well enough to understand the treatment of shock and to avoid inaccurate explanations or responses to learner questions.
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Important
Keep it simple. Different causes can lead to the same urgent first aid priorities. Do not discuss these causes in any detail with learners. If a learner wants to know more tell them where to find the ANZCOR Guideline and suggest they read it after the practical session.
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