Historic Contra-indication to diving
Traditionally, 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
felt that the risk for developing arterial gas embolisms to be great
and
that asthmatics should not be permitted to dive.
In the recent past, workshops have been conducted and the consensus was that asthma should no longer be considered the absolute contraindication to diving that it was previously thought to be. Instead, 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. Recommendations have been developed that include the following:
1). Exercise or cold induced asthmatics should not dive.(BS-AC adds 'emotional attacks')
2). Asthmatics requiring 'rescue or reliever' medication should not dive. Asthmatics on chronic maintenance bronchodilation ('controller') and inhaled steroids are thought to be able to dive. Recommendations vary, however, and the BS-AC recommends that asthmatics should not dive if he/she has needed a therapeutic bronchodilator in the last 48 hours or has had any other chest symptoms.They feel that the asthmatic should not need more than occasional bronchodilators, i.e. daily usage would be a disqualifying factor, but inhaled steroids/cromoglycate/nedocromil are permissible.
3). Mild to moderate asthmatics with normal screening spirometry can be considered candidates for diving. (FEV1/FVC ratio above 85% of predicted)
4). 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 might be 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.
*A copy of the workshop on Asthma and diving entitled "Are Asthmatics Fit to Dive?" can be obtained from the Undersea and Hyperbaric Medical Society, 10531 Metropolitan Ave., Kensington, Md. 20895. The cost is $20.00 plus $2.50 additional for postage and handling.
Recommendations from Others
Here is what the UKSDMC
(United Kingdom Sport Diving Medical Committee) has to say about
asthmatics
and diving:
"Asthma may predispose to air-trapping leading to pulmonary barotrauma
and air embolism, which may be fatal. An acute asthma attack can also
cause
severe dyspnoea which may be hazardous or fatal during diving. These
theoretical
risks should be explained fully to the asthmatic diver. There is little
if any evidence that the mild controlled asthmatic who follows the
guidelines
below is at more risk:
---Asthmatics may dive if they have allergic
asthma but not if they have cold, exercise or emotion induced
asthma.
---All asthmatics should be managed in
accordance
with British Thoracic Society Guidelines.
---Only well-controlled asthmatics may
dive.
---Asthmatics should not dive if he/she has
needed a therapeutic bronchodilator in the last 48 hours or has had any
other chest symptoms.
Control of the Condition
The asthmatic should not need more than occasional bronchodilators,
i.e. daily usage would be a disqualifying factor, but inhaled
steroids/cromoglycate/nedocromil
are permissible. During the diving season he/she should take twice
daily
peak flow measurements. A deviation of 10% from best values should
exclude
diving until within 10% of best values for at least 48 hours before
diving.
The medical examiner should perform an exercise test such as the 18
in (43 cm) step test for three minutes, or running outside (not a
bicycle
ergometer) to increase the heart rate to 80% (210-age). A decrease in
PEFR
of 15% at three minutes post exercise should be taken as evidence of
exercise
induced bronchoconstriction and hence disbars. The patient should be
off
all bronchodilators for 24 hours before the test.
A beta-2 agonist may be taken pre-diving as a preventative but not
to relieve bronchospasm at the time."
Physicians in the UK can be found at our web page at http://www.scuba-doc.com/divuk.htm
Y.M.C.A. Protocols for Diving With Asthma
Based on the latest medical data, the YMCA protocols for asthmatics seem to be the most
reasonable. (http://www.ymcascuba.org/ymcascub/asthmatc.html). It would not be wise to dive if one could not meet these standards.
Links To Asthma
Asthma
and Diving
In-depth discussion of the many divergent recommendations regarding
scuba diving and asthma.
Asthma:
A Clinician's Guide
From the National Asthma Education Program
Office of Prevention, Education, and Control
National Heart, Lung and Blood Institute
National Institute of Health
Bethesda, Maryland 20892
Oregon
Institute of Marine Biology
Fitness to dive guidelines for the scientific diver.
Asthma
And Diving (Rodale's)
Article by Samuel Shelanski, M.D.
Asthma
and Diving
Basic information about asthma and diving from the Australian Lung
Foundation
Asthma and Diving
From Fred Bove's excellent web site
References to asthma and diving
(From Larry "Harris" Taylor, PhD)
Anderson, S. et. al. (1995), Lung Function & Bronchial
Provocation
Tests For
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Benlifer, G. (1997), Warn Asthmatics Of Scuba Diving Risks,
Chest,
112(1),
298-299.
Chapman-Smith, P. (1995), Asthmatic Fitness To Dive,
SPUMS,
25(4),
230-233.
Dear, G. (1997), Asthma & Diving, Alert Diver, Jan/Feb. 32-33.
Elliot, D. (Ed.) ARE ASTHMATICS FIT TO DIVE?, UHMS, Bethesda, MD.
1996,
81
pages.
Farrell PJ Glanvill P (1990), Diving practices of scuba
divers
with asthma,
BMJ. 300(6718), 166.
Godfrey, S. (1986), Controversies In The Pathogenesis Of
Exercise-Induced
Asthma, Respir. Dis. 68, 81-88.
Harrison LJ. (1990), Asthma and diving, Journal of the Florida
Medical
Association. 78(7):431-3.
Hills, B. (1993), Pulmonary Barotrauma: A Possible Role For
Surfactant
In
Opposing The Entry Of Air Into Circulation, SPUMS, 23(2), 59-64.
Martin L. (1992), The medical problems of underwater diving, New
England
Journal of Medicine. 326(22):1497; discussion 1498-9.
Meechan, C. (1995), Bronchial Provocation Testing For
Intending
Divers With
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Neuman TS. Bove AA. O'Connor RD. Kelsen SG. (1994), Asthma and
diving,
Annals of Allergy. 73(4):344-50.
Raper R. Fisher M. Bihari D. (1992), Profound, reversible,
myocardial
depression in acute asthma treated with high-dose catecholamines,
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sudden
death
in status asthmaticus, Radiology. 99(2):271-2.
Shanaker H & Spector, S (1996) Scuba Diving In Individuals
With
Asthma,
Allergy Asthma Proc. 17(6), 311-313.
Simpson, G. & Meehan, C. (1995), Prevalence OF Bronchial
Hyper-responsiveness In A Group Of Experienced Scuba Divers,
SPUMS, 25(4),
249-243.
Sturani C. Sturani A. Tosi I. (1985), Parasympathetic activity
assessed
by
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asthma
and
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Shepard, R. (19770, Exercise Induced Asthma, Med. Sci. Sports, 9(1), 1-10.
Tremonti LP. Halka J. (1992), Death due to pulmonary air
embolism
in
bronchial asthma: case report, Military Medicine. 137(5):194-5.
Twarog F. (1997), Scuba Diving: Asthma & Respiratory Diseases,
in
Weiler,
J.(ed.) Allergic & Respiratory Disease In Sports
Medicine,
Marcel Dekker,
New York, 319-
Walker, D. (1994), Asthma & Diving (Letter), SPUMS, 24(2), 88-90.
Walker, D. (1995), Divers With Asthma: An
Investigation
Is Required,
SPUMS, 25(4), 259-263.
Walker, R. et. al. (1995), Bronchial Provocation Testing In
Royal
Australian Navy Divers & Submarines, SPUMS, 25(2), 254-255.
Weiss LD. Van Meter KW. (1995), Cerebral air embolism in asthmatic
scuba
divers in a swimming pool. Chest. 107(6), 1653-4.
Up to date Medline References on asthma
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