Which combination correctly describes the lethal triad (trauma triad of death) seen in exsanguinating trauma patients?

• A Hypothermia, metabolic alkalosis, polycythaemia
• B Hypothermia, acidosis, coagulopathy ✓
• C Hypocalcaemia, hyperkalaemia, acidosis
• D Anaemia, hypoxia, coagulopathy

Explanation

The lethal triad comprises hypothermia, metabolic acidosis and coagulopathy. Each element amplifies the others: hypothermia impairs platelet function and clotting enzyme activity, tissue hypoperfusion produces lactic acidosis, and acidosis plus hypothermia degrade coagulation, accelerating bleeding. Damage control resuscitation exists specifically to break this cycle through active warming, permissive hypotension with early blood product resuscitation, and rapid haemorrhage control. Some authors add hypocalcaemia from citrate load to form the lethal diamond, but the classical triad is these three components.

Reference: ATLS Advanced Trauma Life Support Student Course Manual, 10th ed.

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Written and medically reviewed by the StethoPrep medical team.