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Subject:Asthma Research Sent on: 10/1/97 3:42 pm
My Lungs wrote
>The day that you can show me research that
>has been done on Astmatics diving, and giving the green light fro them to do
>it, then my way of thinking will change.
As pointed out I'm cluless - however these guys may know a thing or two, they
seem to (however I may be wriong and then I'd be lamer as well) indicate that
some Asthmatics are OK to dive
*****************************************************************************
Asthmatic amateur divers in the United Kingdom
Dr. P. J. Farrell
Introduction
The theoretical reasons why asthmatics should not scuba dive are well known.
In the U.K. the British Sub-Aqua Club (BSAC) has always allowed certain
asthmatics to dive. The subjective opinion has been that we do not see
asthmatics at the hyperbaric treatment centres in the U.K. and hence our
practices work. In 1994 the reality of the situation was investigated. Are
asthmatics over-represented in our accident statistics?
Methods
To determine the prevalence of asthmatics in the U.K. diving population,
twenty five BSAC medical referees were randomly selected who determined the
total number of divers in their diving clubs and the number of asthmatics. The
data was pooled to provide the prevalence figures. Members of the British
Hyperbaric Association and Royal Navy were asked to provide the number of
cases of dysbaric illness (decompression illness and gas embolism) treated in
the period 1989 to the end of 1993 and the number of asthmatics seen.
Results
Out of twenty five BSAC medical referees questioned, nineteen replied. They
recorded 813 active divers of which 31 were asthmatics giving a prevalence of
3.96%. The chambers reported 402 cases of treated dysbaric illness in the
period 1989 to 1993 of which 9 were asthmatics. Statistically chi-squared with
Yates correction was 3.607 (P > 0.5) i.e. asthmatics showed no increase in
dysbaric illness over the general population.
Discussion
The 4% prevalence of asthmatics in the U.K. scuba-diving population is
interestingly similar to Bove et al. [1] where 2.6% of his sample dived
despite being asthmatic, in a country where asthma is considered to be an
absolute contra-indication to diving. I included all cases of decompression
illness and air embolism as one illness as many people believe that they
cannot be separated clinically in most cases. Only one of the chambers
contacted failed to record if a patient was asthmatic and so their data are
not included. However all the hospital case notes were reviewed and asthma was
not mentioned in a single medical history.
In the U.K. the National Sport Diving Medical Committee (representing the
BSAC, the Sub-Aqua Association and the Scottish Sub-Aqua Club) are happy with
the existing guidelines in allowing carefully selected asthmatics to dive, as
there is no evidence that asthmatics are more at risk of decompression illness
than the rest of the U.K. diving population.
Interestingly, Corson et al. [2] in their survey from "Alert Diver" found 279
asthmatics of whom 26.4% had been hospitalized for asthma; of these 5.8% had
been hospitalised 6 times or more and they had a highly significant increased
risk of decompression illness.
The authors commented that the risk needs quantifying according to the
severity of the asthma. It is suspected that in the U.K. many of the divers in
this group would have been advised not to dive. The U.K. policy of enabling
some asthmatics to dive has allowed the exclusion of the more severe cases of
asthma. The asthmatics who are allowed to dive have been educated as to the
safest way of diving.
Interestingly, a recent paper by Neuman et al. [3] has come to much the same
conclusions concerning the fitness of asthmatics to dive. The medical ban on
asthmatics diving has not prevented them diving in the rest of the world,
where an unselected and uneducated group have been shown to be at increased
risk of suffering from decompression illness.
The current U.K. National Sport Diving Medical Committee is currently
reviewing the old BSAC asthma standard to bring it into line with the British
Thoracic Society Guidelines for the treatment of asthma.
References
1.Bove, A.A. et al. Skin Diver Magazine, May 1992.
2.Corson, Moon, Bennett et al. Alert Diver Magazine 1992.
3.Neuman, T.S., Bove, A.A., O'Connor, R.D. & Kelsen, S.G. "Asthma and
diving" Ann. Allergy 73(1994)344-50.
*****************************************************************************
Articles from Skin Diver
Until recently most diving physicians pretty much ruled out scuba diving for
sufferers from asthma. There are very good reasons for them feeling this way:
airway lability with obstruction are the hallmarks of asthma, blockage being
precipitated by exercise, inhalation of cold, dry air, dusts, fumes and
emotional stress. Asthmatics can sometimes be asphyxiated by severe attacks on
the surface - one can imagine how devastating an attack would be under the
surface of the water. Asthmatics over the age of 12 usually have chronic
airway obstruction, which can also lead to lung over-pressure accidents (blown
out bleb) on surfacing from a dive, in turn leading to AGE (air gas embolism),
paralysis and /or death.
This having been said - there are now very excellent diving physicians who
feel that asthma should not be considered an absolute contraindication to
diving. My friend Dr. Fred Bove feels that based on the available accident
statistics that asthmatics completely controlled by medication and who have
normal lung function studies should be cleared for diving. (Bove et al; Annals
of Allergy; Vol 73, October 1995). Of course, each case should be evaluated on
its' individual merits and the final decision made by an aware diving doctor,
not the diver himself or some other diving-related person.
*****************************************************************************
Currently, the diving medical community is rethinking the medical hazards of
asthma and compressed air diving. Previously, because of the risk of gas
embolism which frequently has a fatal outcome, asthma was thought to be an
absolute comtraindication to diving. However, diving accident statistics do
not support the theoretical hazard and a more liberal approach is being taken
to attempt to identify the asthmatics that can dive with relative safety.
From ST Medical Forum 6/29/96:
"Historically, asthma has been thought to be an absolute contraindication to
diving. The classical thought is that the asthmatic has air-trapping
associated with the constrictive airway disease, bronchospasm and mucous
plugging. Because of these factors the vast majority of diving physicians feel
that the risk for developing arterial gas embolisms to be great and that
asthmatics should not be permitted to dive.
More recently, at an Undersea and Hyperbaric Medical Society Workshop, it was
decided that asthma should no longer be considered the absolute
contraindication to diving that it was previously thought to be. Rather, the
potential diver must be made aware that they are facing a relative risk of an
event that occurs in less than 1 in 250,000 dives. They came up with the
following recommendations:
1.Exercise or cold induced asthmatics should not dive
2.Asthmatics requiring chronic medication should not dive. Mild to
moderate asthmatics with normal screening spirometry can be considered
candidates for diving. (FEV1/FVC ratio above 85% of predicted)
3.If an asthmatic has an attack, screening spirometry should be done
and the individual should not dive until his airway function returns to
normal.
Finally, it would appear that our fears about the dangers of asthmatics diving
have been overstated and that there is a sizable group of asthmatics who can
dive at an acceptable level of risk.
(Neuman, T.S., Bove,A.A., et al., Asthma and Diving. Ann. Allergy. 73:
344-350. 1994)"
Mail Address : graeme_davison@ne*.co*
BSAC Advanced Diver / Open Water Instructor : IANTD Trimix Diver
TDI Advanced Nitrox Instructor : NSS-CDS Full Cave : NACD Full Cave
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