The Lethal Pentagon: Time as the Central Driver of Trauma Physiology.

Existing frameworks such as the lethal triad and lethal diamond describe key physiological derangements, including hypothermia, acidosis, coagulopathy, and hypocalcemia. However, they primarily define whether abnormalities are present rather than how long patients remain exposed to them. This manuscript proposes the lethal pentagon: a time-aware extension of the lethal diamond in which duration is treated as the contextual variable that changes the meaning and reversibility of trauma physiology. Identical biochemical values may represent different clinical trajectories depending on whether they follow brief shock or prolonged hemorrhage. The framework is particularly relevant to prolonged casualty care, delayed evacuation, and trauma systems in which time to definitive hemorrhage control is uncertain. Future research and quality improvement should report when derangements occur, how long they persist, and how rapidly they resolve. Formalizing time may improve handover, triage, audit, and trauma system design.