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Exercise-induced Bronchoconstriction with Firefighting Contained Breathing Apparatus

Seccombe Leigh M; Buddle, Lachlan; Brannan, John D; Peters, Matthew J; Farah, Claude S
Medicine & Science in Sports & Exercise: Post Acceptance: September 12, 2017
doi: 10.1249/MSS.0000000000001424
Original Investigation: PDF Only

ABSTRACTPurposeProtective self-contained breathing apparatus (SCBA) used for firefighting delivers decompressed (cold), dehumidified air that may enhance the severity of exercise-induced bronchoconstriction (EIB) in those susceptible. We investigated the effect of SCBA during exercise on airway caliber in people with asthma and healthy controls.MethodsTwo exercise challenges (EC) designed to elicit EIB were performed on separate days within one week. The initial challenge was breathing room air (ECRA) with workload titrated to elicit >60% estimated maximum voluntary ventilation. The exercise intensity was repeated for the second challenge using SCBA (ECSCBA). Forced expiratory volume in one second (FEV1) was measured before and up to 20min after exercise. Bronchial hyperresponsivenss (BHR) to the hyperosmolar mannitol test was measured in the subjects with asthma.ResultsTwenty subjects with current asthma (mean[SD] age 27[6] years) and 10 healthy controls (31[5] years, p=0.1) were studied. The % fall in FEV1 following ECSCBA was greater in the mannitol positive asthma subjects (14.4 [15.1]%) compared to mannitol negative asthmatic subjects (1.6 [1.7]%, p=0.02) and controls (2.3 [2.3]%, p=0.04). The FEV1 response was not different between ECRA and ECSCBA (0.49 [5.57] %, p=0.6). No BHR to mannitol (n=7) was highly sensitive for identifying a negative response to ECSCBA (negative predictive value 100%).ConclusionsSCBA does not increase the propensity or severity for EIB in subjects with BHR. Those subjects with asthma but no BHR to inhaled mannitol did not exhibit EIB. BHR to a hyperosmolar stimulus maybe considered a useful screening tool for potential recruits with a history of asthma.

Purpose

Protective self-contained breathing apparatus (SCBA) used for firefighting delivers decompressed (cold), dehumidified air that may enhance the severity of exercise-induced bronchoconstriction (EIB) in those susceptible. We investigated the effect of SCBA during exercise on airway caliber in people with asthma and healthy controls.

Methods

Two exercise challenges (EC) designed to elicit EIB were performed on separate days within one week. The initial challenge was breathing room air (ECRA) with workload titrated to elicit >60% estimated maximum voluntary ventilation. The exercise intensity was repeated for the second challenge using SCBA (ECSCBA). Forced expiratory volume in one second (FEV1) was measured before and up to 20min after exercise. Bronchial hyperresponsivenss (BHR) to the hyperosmolar mannitol test was measured in the subjects with asthma.

Results

Twenty subjects with current asthma (mean[SD] age 27[6] years) and 10 healthy controls (31[5] years, p=0.1) were studied. The % fall in FEV1 following ECSCBA was greater in the mannitol positive asthma subjects (14.4 [15.1]%) compared to mannitol negative asthmatic subjects (1.6 [1.7]%, p=0.02) and controls (2.3 [2.3]%, p=0.04). The FEV1 response was not different between ECRA and ECSCBA (0.49 [5.57] %, p=0.6). No BHR to mannitol (n=7) was highly sensitive for identifying a negative response to ECSCBA (negative predictive value 100%).

Conclusions

SCBA does not increase the propensity or severity for EIB in subjects with BHR. Those subjects with asthma but no BHR to inhaled mannitol did not exhibit EIB. BHR to a hyperosmolar stimulus maybe considered a useful screening tool for potential recruits with a history of asthma.

Corresponding author: Dr Leigh Michelle Seccombe, Department of Thoracic Medicine, Level 7 West, Concord Repatriation General Hospital, Hospital Rd, Concord 2139 NSW Australia. Email: leigh.seccombe@sswahs.nsw.gov.au

Acknowledgments: Health and Safety Branch, Fire and Rescue New South Wales, provided some funding support. The conduct of the research and preparation of the article was independent from the funder. Competing interests: None declared for L Seccombe, L Buddle, M Peters or C Farah.

J Brannan’s prior employee, Royal Prince Alfred Hospital (RPAH) receives royalties for the sale of the mannitol test (Aridol/Osmohale), however does not receive royalties on Australian sales. J Brannan receives a 10% portion of the royalties paid to RPAH. The results of this study are presented clearly, honestly, and without fabrication, falsification, or inappropriate data manipulation. The results of the present study do not constitute endorsement by ACSM.

Accepted for Publication: 1 September 2017

© 2017 American College of Sports Medicine