A Survey of the Incidence of Acute Decompression Illness in a Group of Veteran Canberra Aircrew
S J Mitchell and V M Lee
Introduction
Aircrew operating future fighter aircraft are likely to be exposed
to cabin altitudes in excess of 18,000 ft for prolonged periods.
Altitude chamber experiments at such medium altitudes have shown a
higher than expected incidence of decompression illness. There are
little published data on the prevalence of decompression illness in
aircrew exposed to similar operational profiles. Retrospective
information was therefore collected from aircrew exposed to these
altitudes in the Canberra aircraft.
Methods
A postal questionnaire was sent to 550 members of a Canberra
aircraft aircrew veterans group. Respondents were asked to record
age, height, weight, flying history, exercise frequency, alcohol
consumption and exposures to cabin altitudes in excess of 18,000 ft
and 25,000 ft. They were then asked to report whether they had
experienced a range of symptoms during or after flights. If
symptoms had been experienced, questions were asked about
frequency, duration, reporting, treatment and personal strategies
to reduce risk.
Results
Questionnaires were received from 252 (46%) aircrew off whom 43.2%
were pilots and 53.6% were navigators. The mean hours flown in
Canberra aircraft was 1562 (range 5-7231). One third of responders
indicated exposures above 18,000 ft for greater than 50% of
Canberra flights. 14.2% of responders had been exposed to above
25,000 ft on more than 25% of flights, many with durations of over
1 hour. Of responders, 21.4% reported upper limb pain during flight
above 18,000 ft rarely or more and similarly 13.9% reported pain in
the lower limb. Of those experiencing limb pain, 78.4% indicated
that generally the pain was slight or mild and did not interfere
with normal duties, whereas 21.6% reported moderate pain
interfering with concentration. 18.6% of responders indicated that
they had needed to descend or abort a flight due to a crew member
developing symptoms of decompression sickness.
Conclusions
The results suggest that symptoms consistent with decompression
illness occur more frequently than aircrew officially report.
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