What are the four different types of shock?
Shock is the term used to describe the condition of a casualty when the oxygen supply to the tissues is inadequate to meet the needs of the body.
First aiders and first responders should understand the different causes of shock and be aware of their signs and symptoms.
Shock may result from:
- Fluid loss, e.g. blood loss, plasma loss in burns, vomiting and diarrhoea
- Reduction of fluid flow through the blood vessels, e.g. myocardial infarction or blockage of major arteries by tension pneumothorax or pulmonary embolism
- Increase in the size of the containing vessels (without increase in fluid volume), e.g. dilatation of large peripheral blood vessels from spinal injury, infection (sepsis) or anaphylaxis (which also causes fluid loss)
The four categories of shock
Shock can be split into four categories:
Hypovolaemic shock – from blood loss or excessive fluid loss (eg: major burns or D&V)
Cardiogenic shock – the heart is unable to circulate enough blood volume to maintain adequate tissue perfusion. This can happen after a heart attack or during an acute episode of heart failure.
Obstructive shock – can be caused by an obstruction in the cardiovascular system. Examples include a pulmonary embolism (blood clot in the lung) and pneumothorax (collapsed lung).
Distributive shock – occurs as a result of poor distribution of blood to the tissues, leading to inadequate tissue perfusion. This type of shock is seen in spinal, septic, and anaphylactic shock. This is also known as relative hypovolaemia.
