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Chapter 34 — 8
HUMAN FACTORS
MEDICAL, PSYCHOLOGICAL
AND PHYSIOLOGICAL
In at least
25% of cases, the diver had a pre-existing disease which should have excluded
him from diving
(compared to 8-10% in the potential diver trainee population). The diseases
either killed the diver or predisposed him to the diving accident.
In assessing the cause of scuba fatalities, it is too easy to ignore the disorders which have no
demonstrable pathology, such as panic and fatigue, but to do so results in less understanding
of the incident. Drowning obscures many other pathologies and some, such as asthma or the
sudden death syndrome, may not show up at autopsy.
Panic
39% of deaths were associated with panic.
Panic is a psychological stress reaction of
extreme anxiety, characterised by frenzied and irrational behaviour. It is an unhelpful
response which reduces the chance of survival. This topic is covered in detail in Chapter 7.
Evidence of panic was derived from witness accounts of the diver's behaviour, in the
Australasian series. Other studies suggest a 40–60% incidence of panic.
Panic was usually precipitated when the diver was confronted by unfamiliar or threatening
circumstances such as LOA, OOA, poor visibility, turbulent water, unaccustomed depth,
buoyancy problems (usually insufficient buoyancy), or separation from diving companions.
After panicking, the diver frequently behaved inappropriately by actions such as failure to
ditch weights or inflate the B.C., rapid ascent, or abandoning essential equipment such as the
mask, snorkel and regulator.
Fatigue
In 28% of cases fatigue was a factor.
Fatigue is a consequence of excessive exertion, and
limits the diver's capacity for survival. Physical unfitness aggravates it.
It commonly arose from a variety of circumstances including attempting to remain on the
surface while overweighted, long swims in adverse sea conditions or swimming with
excessive drag from an inflated B.C..
The fatigue factor was not restricted to unfit divers — under special circumstances any diver
will become fatigued. In some cases the fatigue was associated with salt water aspiration
syndrome, cardiac complications or asthma.