Asthma and Diving
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, workshops have been conducted and the consensus felt 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 some recommendations included below:
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 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.
*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.