lethal triad
Combination of hypothermia, acidosis, and coagulopathy that creates a cycle of worsening physiology in trauma patients.
Full Definition
The lethal triad refers to the deadly combination of hypothermia, metabolic acidosis, and coagulopathy that commonly develops in severely injured trauma patients and represents a state of physiologic exhaustion. Each component exacerbates the others, creating a self-perpetuating cycle of deterioration. Hypothermia impairs coagulation enzyme function, acidosis reduces cardiac contractility and peripheral vascular tone, and coagulopathy leads to continued bleeding and further blood loss. Recognition of this triad is critical in trauma surgery decision-making, often prompting abbreviated surgical procedures and intensive resuscitation efforts. Breaking this cycle requires aggressive warming, correction of acidosis, and blood product resuscitation rather than continued surgical intervention.
Usage
Usage note: Specific to trauma/critical care; distinct from Beck's triad (cardiac tamponade) or other medical triads.
In Context
- "Development of the lethal triad necessitated immediate cessation of surgery and transfer to the ICU." — trauma surgery operative note
- "The patient exhibited components of the lethal triad with temperature 34.2°C, pH 7.15, and clinical coagulopathy." — critical care consultation