Evaluation of Fitness to Utilize Self-Contained Breathing Apparatus (SCBA)

Abstract

Background. Breathing dry, cold air may cause bronchoconstriction in asthmatics working with self-contained breathing apparatus (SCBA). Air delivered by SCBA is cooler than ambient air. It is unclear whether a bronchial challenge test using mannitol (BCTM) can predict a fall in forced expiratory volume in one second (FEV₁) during exercise with SCBA. Methods. A prospective study of army recruits assigned to work with SCBA was carried out. Participants completed self-administered questionnaires on respiratory symptoms, BCTM, and measurement of exhaled nitric oxide. A subgroup of participants with a positive BCTM (BTCM+) and with negative BCTM underwent exercise test on bicycle ergometer (ET) while using SCBA. Results. One hundred and six recruits participated in this study. One hundred and two underwent BCTM and 28 ET. Nineteen out of 97 participants had a positive BCTM and 6 out of 27 had a positive ET. Seventeen out of 19 participants with a positive BCTM had current respiratory symptoms such as wheeze, cough, chest tightness, or dyspnea. Sensitivity, specificity, positive predictive value, and negative predictive value for a positive ET under SCBA were 100%, 64%, 43%, and 100% for the BCTM, respectively. BCTM-positive participants with respiratory symptoms had more physician consultations during MBT compared to BCTM-negative participants. Conclusion. Despite medical evaluation and exclusion of asthmatics by a physician during conscription, a high proportion of recruits assigned to work with SCBA smoke, have respiratory symptoms, and have a positive BCTM suggesting current asthma. BCTM has a high sensitivity to predict a significant fall in FEV₁ after exercise with SCBA and participants with a positive BCTM tend to use more health care resources during basic military training. Recruits should be counseled about smoking cessation prior and during basic military training.

Keywords :

• asthma
• exercise test
• mannitol
• military
• SCBA

Acknowledgments

We would like to thank all members of the SAF medical service team for their invaluable help for conducting this study, as well as Pharmaxis Ltd., Frenchs Forest, Australia, for providing the Aridol(tm) test kits and ndd Medizintechnik AG, Zurich, Switzerland, for providing two Easyone spirometers with printer and mouthpieces at no charge for this study. Further, we would like to thank Alicia Wright, M.Sc. Exercise Science, for her help in preparing the manuscript.