Diving and pressure deaths: barotrauma and decompression
- Finding
In a diver's death, drowning, arterial gas embolism from lung barotrauma, decompression sickness and natural causes such as heart disease must be told apart.
What it is
Water pressure rises with depth and the volume of gases changes with it (Boyle's law). If a diver ascends quickly without breathing out, the trapped air overstretches and ruptures the alveoli (pulmonary barotrauma); air enters the pulmonary veins and reaches the arteries of the brain and heart (arterial gas embolism), with loss of consciousness within minutes. Decompression sickness is caused by bubbles of inert gas dissolved in the tissues, after long or deep dives. Drowning remains the commonest final cause, often after another problem, and in older divers cardiac deaths are increasing. The great difficulty at autopsy is that gas also appears after death: from decompression of the body as it is brought up, from putrefaction or from resuscitation.
How to tell it apart
- Criteria for gas embolism from barotrauma: rapid ascent followed by loss of consciousness, gas in the left heart and cerebral arteries, low likelihood of artefact, and emphysema limited to the chest or pneumothorax.
- Postmortem decompression gas appears in bodies recovered from depth and can mimic embolism.
- Putrefaction and resuscitation also produce gas: an early autopsy reduces error.
- Arterial gas embolism from barotrauma explains a share of diving deaths; drowning remains the commonest cause.
How to recognise it
- Subcutaneous or mediastinal emphysema around the chest, and pneumothorax.
- Gas in the left heart chambers and in the cerebral arteries of the circle of Willis.
- Overdistended and ruptured air spaces on lung histology.
- Haemorrhage in the middle ear and paranasal sinuses from descent barotrauma.
- Signs of drowning when that was the outcome.
How it forms
- Rapid ascent with a closed glottis or without breathing out: the gas expands, ruptures alveoli and enters the circulation.
- A long or deep dive with an ascent that skips the necessary stops: dissolved inert gas forms bubbles in tissues and veins.
- Panic, running out of gas or a cardiac event can start the chain that ends in drowning.
Next step: what to do and document
- Ask the authority to keep the diving equipment untouched and hand it over under chain of custody for expert analysis.
- Record the dive profile from witnesses and the dive computer: depth, time and rate of ascent.
- Request CT of the body before the autopsy, and an autopsy as early as possible to limit putrefactive gas.
- Take samples for toxicology and examine the heart in detail: heart disease is common in older divers.
- If the dive was work-related, record it: autopsies are singled out when a work accident is suspected (Decree 786 of 1990, art. 7(b)).
- Official text checked on 2026-11-13 at funcionpublica.gov.co.
Common mistakes
- Diagnosing gas embolism from gas found in a putrefied body or one recovered from depth without considering artefact.
- Opening the skull and chest without preparing to look for gas, with prior imaging or opening under water.
- Forgetting the equipment, which experts must examine, including analysis of the gas in the cylinders.
- Concluding drowning without looking for the problem that started it.
Test yourself
Think of the answer, then tap the question to see it.
What mechanism produces arterial gas embolism in a diver?
A rapid ascent without breathing out expands the trapped gas, ruptures alveoli, and air enters the pulmonary veins and reaches the systemic arteries.
How does decompression sickness differ from gas embolism from barotrauma?
Decompression sickness is due to bubbles of dissolved inert gas after long or deep dives; embolism is due to lung rupture from gas expanding on ascent.
Why does gas found at a diver's autopsy not prove gas embolism?
Because it also appears from decompression of the body during recovery, from putrefaction or from resuscitation.
What is the commonest final cause of death in diving accidents?
Drowning, often preceded by another problem such as panic, running out of gas or a cardiac event.
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Educational content on forensic and legal medicine; not legal advice and no substitute for the technical guides of Colombia's National Institute of Legal Medicine and Forensic Sciences. Laws change: each page links the official text and says when it was last checked. For a real case, follow the guide in force and ask the competent authority.
Sources: Pulmonary barotrauma in SCUBA diving-related fatalities: a histological and histomorphometric analysis (Forensic Science, Medicine and Pathology (PMC), 2023); A Temporal Comparison of 50 Years of Australian Scuba Diving Fatalities (International Journal of Environmental Research and Public Health (PMC), 2025); Decreto 786 de 1990: autopsias clínicas y médico-legales y viscerotomías (compilado en el Decreto 780 de 2016) (Función Pública, Gestor Normativo, 1990).
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