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Chapter 33 — 4
COLD
OR
HYPOTHERMIA
(
SEE CHAPTERS
3, 27
AND
35)
Exposure to cold water can cause an progressive and excessive fall in body temperature
which can make a diver initially confused (at a body temperature of around 34
°
C) and then
unconscious (below 30
°
C). A diver suddenly entering cold water can sometimes develop a
hypertensive spike or cardiac rhythm disturbances which can produce immediate
unconsciousness from cardiac or cerebral accidents (heart attack or stroke).
MARINE ANIMAL
INJURIES
(
SEE CHAPTER
29)
Venomous animals can cause unconsciousness either from the direct effect of the venom on
the brain, from hypoxia due to respiratory paralysis, or due to inadequate cerebral circulation
from a lowering of blood pressure. Shock from blood loss after shark attack can also cause
unconsciousness.
Case History 33.4.
A group of divers on their first dive on a tropical reef eagerly took to the water. They
returned later with speared fish, coral and shells among which were several varieties of venomous cone shells
which they had handled, and in some cases, carried under their wet suits. A member of the boat crew recognised
the cone shells and advised the divers of their narrow escape.
Diagnosis:
potential loss of consciousness, or "accidents looking for somewhere to happen".
DECOMPRESSION
SICKNESS
(
SEE CHAPTERS
14–16)
Cerebral Decompression Sickness can lead to unconsciousness. It is more likely after deep
dives and repetitive diving.