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Chapter 21 — 5
Pulmonary Effects
These effects will usually resolve spontaneously if the supplementary O
2
administration is
ceased as soon as symptoms develop. If it is essential to continue O
2
therapy however, a
reduction in the partial pressure of O
2
given will slow the development of toxicity. Short
periods of 'air breathing' (or Heliox), 5 minutes every half hour, are often used by
experienced doctors to delay oxygen toxicity during O
2
therapy.
CONCLUSIONS
1.
Recreational divers should not use O
2
enriched diving equipment. Technical divers should
not expose themselves to O
2
pressures greater than 1.6 ATA or durations that could cause
respiratory manifestations.
2.
Resuscitation training with O
2
equipment is of great value to divers and dive boat
operators. In diving accidents, the delayed risks of O
2
toxicity are outweighed by the benefits
of treating the hypoxic diving casualty.
3.
The use of O
2
in the first-aid treatment of decompression sickness and pulmonary
barotrauma should always be undertaken whilst bearing in mind the prospect of eventual
pulmonary oxygen toxicity. Breathing air for 5 minutes after 25 minutes of O
2
is one way of
reducing the risk of pulmonary toxicity, but this should be discussed with the diving
physician who will ultimately manage the case.
4.
During therapeutic recompression using O
2
, the use of short air or Heliox breaks during the
treatment reduces cerebral and pulmonary O
2
toxicity.
5.
There are other logistical problems with the use of oxygen, and some of these are
discussed in Chapter 40.