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Chapter 34 — 3
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Major Causes of Death identified at Autopsy.
According to death certificates, most divers ultimately drowned (over 80%), but a number of
factors usually combined to incapacitate the diver before this terminal event. Drowning is
really only the final act in a sequence of events that lead up to this. It is a reflection of the
medium in which the accident happens, more than the accident itself. Often it obscures the
real cause of death. Unless there are other factors, drowning should never happen to a scuba
diver, as he carries his own personal air supply with him! Drowning develops because of
preceding problems, such as cardiac disease, pulmonary barotrauma, the stress disorders,
unconsciousness from any cause, salt water aspiration, trauma, equipment difficulties or
environmental hazards, etc. These are referred to in the following sections and in other
chapters.
CONTRIBUTING FACTORS
Deaths usually followed a combination of difficulties, which alone may have been
survivable. The factors contributing to deaths are easier to understand when classified, and
we have categorised them into the following groups:
•
Diving Techniques
(Inadequate air supply, buoyancy, buddy system)
•
Human Factors
(medical, physiological, psychological)
•
Equipment Factors
(misuse, faults)
•
Environmental Factors.
DIVING TECHNIQUES
Inadequate Air Supply
In the ANZ survey in
half the deaths (56%), critical events developed when the diver was
either running low or was out-of-air (LOA, OOA).
When equipment was tested following
death, few victims had an ample air supply remaining. The DAN survey found 41% in this
situation.
Most problems arose when the diver became aware of a low-on-air (LOA) situation. Some
divers then died while trying to snorkel on the surface, attempting to conserve air (8%).
Concern about a shortage of air presumably impairs the diver's ability to cope with a second
problem developing during the dive, or causes the diver to surface prematurely and in a
stressed state of mind, where he is then unable to cope with surface conditions. In many cases
the LOA diver faced these difficulties alone, as his buddy who had more air, continued the
dive oblivious to the deteriorating situation (see later). LOA situations should be avoidable
by adequate dive planning, using a cylinder with ample capacity for the planned dive, and
frequent observation of the contents gauge.
A particularly dangerous technique was to intentionally use all the available air (breathing the
tank dry). Then there is much less opportunity to cope with unexpected eventualities and