SCUBA Diving and Asthma
Contributed by Nerissa Penfold
For as long as I can remember I wanted to SCUBA dive. I remember
being fascinated by my dad’s cylinders of air with yellow flaking paint
and belts of lead weights that lay around the house, and the promise of
what lay beneath the surface of the sea. As luck would have it, by the
time I seriously started thinking about diving I had been diagnosed
with adult asthma. More than 10% of Australians (over 2 million people)
suffer from asthma and Australian doctors are renowned for
being
conservative when it comes to diving medicine. A diagnosis of asthma
will almost certainly preclude you from SCUBA diving.
Asthma is viewed as a serious risk factor for a number of
reasons.
An asthmatic may be more prone to lung overexpansion injury if
narrowing of the airways occurs during the dive and trapped air expands
during ascent. A further risk is the use of bronchodilators such as
Ventolin which may reduce the lungs’ effectiveness in filtering out
nitrogen bubbles, potentially increasing the risk of suffering an
arterial gas embolism. Additionally, simply breathing cool,
dry air,
sometimes contaminated by salt water, can cause an asthma attack – a
severely risky proposition when underwater at depth.
I scoured the internet looking for information about diving with
asthma. Opinions on the topic were varied and there were major
differences in rules set by the certifying bodies in different
countries. The UK for instance seems to be quite relaxed in its
approach to asthmatic divers, whereas Australia has very strict
guidelines. Even amongst the medical profession and asthma foundations
there are varying opinions. Asthma NSW puts SCUBA diving in the
category of sports that asthmatics should absolutely avoid. Dr David
Batt from the National Asthma Council of Australia however believes
that an asthma sufferer, in consultation with their doctor, and with
the assistance of lung function testing, should make an informed
decision whether or not to dive.
The consensus seemed to be that if the asthma is mild, controlled,
not
exercise induced and is without acute “attacks”, the sufferer
could potentially still dive. Many sources recommended the hypertonic
saline challenge test to determine if airway narrowing occurs when
breathing in air and saline mist. Armed with this information and
confident that with my symptoms I would be passed fit, I went to see
the dive doctor for a medical. The doctor immediately referred me to
the Department of Respiratory Medicine at the Prince of Wales Hospital,
Randwick in Sydney to undergo the bronchial challenge test. He was not
confident of a positive outcome and tried to assure me that I could
still be a “great snorkeller”. I made an appointment at the hospital
and was advised not to take any preventer or reliever medication in the
24 hours prior to the test.
On the day of the test I arrived at the hospital full of
expectation,
aware that very soon I would know whether I could fulfil a lifetime’s
ambition to SCUBA dive. The technician who ran the procedure advised
that the test would take about half an hour. During this time I would
be exposed to saline, in the same concentration as sea water, via a
nebuliser. Initially I would be exposed for 30 seconds, followed by a
spirometer test to measure lung function. The period of exposure was
then doubled each time until the final 8 minute exposure. Before the
test commenced 3 spirometer readings were taken and averaged. In order
to “pass” the test your lung function must decrease by no more than 10%
from the baseline reading. A reduction in lung function of more than
10% would most likely result in the test being terminated and me going
home disappointed.
Breathing in the nebulised saline was a strange sensation. It was
dry,
uncomfortable and induced a slight burning sensation in my throat,
whilst the condensation forming in the nebuliser mask caused salty
water to drip down my face and all over my clothes. In between each
exposure I would cough and feel a need to drink water, but amazingly my
spirometer readings showed improvement after some exposures and after
the 8 minute exposure only displayed a 3% decrease in function.
The smile didn’t leave my face for the rest of the day! The
remainder
of my dive medical went smoothly and I got the all clear to dive. Two
weeks later I completed the PADI Open Water certification and
experienced no issues with my breathing, just amazement that I was
finally breathing underwater. A year on and now with the Advanced Open
Water certification I’ve notched up 50 dives and have travelled to some
amazing places including Truk Lagoon and the Coral Sea. And I still
haven’t experienced any asthma-like symptoms underwater. For me, the
hypertonic saline opened up a whole new (underwater) world.
Of course, everyone is different and you should never make any
change
to your asthma medication or treatment plan without first consulting
your doctor.
References:
- http://www.nationalasthma.org.au/content/view/592/1027/
- http://www.dive-the-world.com/newsletter-200404-asthma-diving.php
- http://www.nationalasthma.org.au/content/view/647/951/