A 22-year-old man dives into a cold mountain stream and immediately floats motionless on the surface. He is pulled out within two minutes, dead. Autopsy shows an empty stomach, dry lungs, no froth, and no diatoms in the marrow. The MOST likely mechanism of death is:

• A Vagal inhibition from contact of cold water with the body surface ✓
• B Aspiration of water with secondary cardiac arrhythmia
• C Acute non-cardiogenic pulmonary oedema developing over minutes
• D Hypothermia-induced ventricular fibrillation after core cooling

Explanation

This is immersion syndrome, a form of asphyxia by vagal inhibition. Sudden contact of cold water with the skin, especially over the abdomen or with water entering the ear canal and pharynx, triggers intense vagal discharge producing cardiac arrest within moments. Because death occurs before any inhalation, the lungs are dry, there is no froth and the diatom test is negative, giving a wholly negative autopsy. Hypothermic fibrillation requires far longer exposure than two minutes, killing the most tempting distractor.

Reference: Parikh's Textbook of Medical Jurisprudence, Forensic Medicine and Toxicology, 6th ed.

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Written and medically reviewed by the StethoPrep medical team.