Diving Related Deaths
Dr A McLeod
This mini-article deaths related to SCUBA diving. This info is largely
referenced from Knights
Forensic Pathology.
SCUBA divers fall into two broad categories:
- Pleasure divers (about 1/75,000 dives results in a death, about 6
per year in the UK).
- Professional divers e.g. oil rig or navy divers
The cause of death in diving accidents will likely be either
- Drowning.
- Physical trauma (e.g. shark attack, rock fall).
- Hypothermia
- Complications of pressure changes.
Drowning, hypothermia and physical trauma of varying types will be
covered elsewhere - the rest of this article will deal with dysbarysm (damage from pressure
changes) and in particular, barotrauma
(mechanical damage from gas released into tissues).
How barotrauma occurs in SCUBA diving:
- Pressure increases with depth - each 10m depth increases pressure
by 1 atmosphere.
- In a non-solid diving suit the pressure of the breathing gas is
increased to match.
- The breathing gas at depths less than 50m is a mixture of
nitrogen and oxygen
- Henry's law states that solubility of a gas increases with its
partial pressure
- At the higher pressures underwater the partial pressure of
nitrogen in the bloodstream increases
- And more nitrogen becomes dissolved in the blood
- Decreasing pressure too quickly (e.g. by surfacing quickly)
forces the nitrogen out of solution into bubbles
- These bubbles can occlude vessels e.g. spinal, coronary, cerebral
Other structures that may suffer dysbaric trauma
- Sinuses - severe pain from gas expansion
- Eardrums - rupture from expansion of gas in the inner ear
- Lungs - formation of bullae - possible rupture of bullae to give
pneumothorax or air embolism to the heart.
- Pain from any of these may contribute to events leading up to
drowning.
Conducting the autopsy of a diving related death:
- When death occurs either during or shortly after diving it is
important
that an expert looks over the equipment of the diver - this should not
be done by an amateur diver.
- Ideally the autopsy should take place in a decompression chamber
- this
is almost certain to be impossible however and the pathologist must
accept that there will be artifacts of decompression to be found.
- Photographs at every stage and and X-rays of chest and each major
joint should be taken as part of the autopsy.
Indicators of dysbarism / barotrauma in autopsy:
- Crepitance of the skin (usually head, neck and thorax) from
surgical emphysema.
- Signs of subpleural, retroperitoneal or mediastinal emphysema.
- Subpleural bullae.
- Rupture of the tympanic membrane(s) seen on otoscopic examination.
- Pneumothorax (first by radiology then by puncturing an
intercostal space under water held in the lateral skin flap).
- Examination of the heart for presence of bubbles (radiologically
or via froth in the chambers).
- The middle cerebral, basilar and vertebral arteries* should be
clamped and cut below the clamp before removal of the brain. The brain
can then be submerged and the clamps removed. Air bubbles from the
vessels are indicative of barotrauma.
*But not the veins - bubbles in these
occur artefactually during removal of the calvarium.
