Value of Bronchial Challenge in Scuba Diving Candidates

Abstract

Bronchial challenges were effected with carbachol in 76 subjects who were candidates for a scuba diving group. Bronchial reactivity was assessed through airway resistance and forced expiratory volume in 1 sec (FEV1) measurements. Medical interrogation had revealed symptoms of recent (RA) or ancient (AA) asthma, or allergic rhinitis (AL). Nearly half of the subjects (47%) presented bronchial hyperresponsiveness (BHR), which was much more frequent in the RA group, but whose strength did not depend on clinical presentation. Prevalence of BHR was fairly high (36%) in the AL group. BHR constituted a contraindication to scuba diving because it may promote pulmonary barotrauma.

A Review of Asthma and Scuba Diving

“…In fact, there is one study that showed a significantly higher prevalence of airway hyperresponsiveness to histamine in military scuba divers when compared to non-diving control subjects, whereas divers and controls did not differ significantly with respect to atopy and smoking. [45] It is important to note that a shift from nose breathing to combined mouth and nasal breathing at ventilation levels exceeding 30 L/min may account for a greater deposition of inhaled particles to the lower airways, and inadequately conditioned air may reach the lower airways. [57] This mechanism may intensify the airways' response to dehydration injury in mouth breathing scuba divers when compared to other sports.…”

“…[5,8] A recent study which investigated 76 diving candidates with a history of recent or ancient asthma, or a history of allergic rhinitis, showed that nearly half of the subjects (47%) presented airway hyperresponsiveness to a carbachol challenge. [45] Only a few studies systematically investigated the association between airway hyperresponsiveness and diving. In a study of 28 consecutively recruited military scuba divers with a diving experience of at least 50 dives, 12 subjects (42.9%) significantly responded to a histamine challenge.…”

Can asthmatic subjects dive?

“…In 30 subjects, the bronchial provocation test with hypertonic saline was positive (a fall in FEV1 of more than 15%) and they were excluded from diving. In subjects with a borderline post-saline fall in FEV1 (10-14.9%), the authors speculate that diving may be permissible if tests of static lung volumes and expiratory flows at low lung volumes derived from the flow-volume loop are normal [39]. The Thoracic Society of Australia and New Zealand [38] suggests that direct challenge tests are nonspecific and bronchial hyperresponsiveness to agents such as methacholine should not be considered an absolute contraindication for diving.…”