Causes of cardiovascular deterioration: Shock

Shock is defined as a generalised state of tissue hypo-perfusion, where there is insufficient blood supply to the tissues, depriving them of the oxygen and nutrients needed to function and survive. Although there are many different causes of shock, the signs and symptoms are similar. With critically unwell patients septic shock (distributive shock) is the most frequently seen form of shock, while obstructive shock is relatively uncommon.

Circulatory shock can arise from four potential mechanisms:

  • Hypovolemia

    Internal or external fluid loss

    Examples: excessive GI losses from diarrhoea and vomiting, excessive sweating, haemorrhage.

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  • Cardiogenic

    An issue with the ability of the heart to pump blood effectively.

    Examples: MI, myocarditis, chronic or acute heart failure, cardiac arrhythmias.

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  • Obstructive shock

    Related to physical obstruction of the heart or great vessels.

    Examples include cardiac tamponade, pulmonary embolism or tension pneumothorax.

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  • Distributive shock

    Abnormal distribution of blood flow to the organs and tissues.

    Examples include sepsis (most common), anaphylactic shock.

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