title: Effects of water immersion on pulmonary function in asthmatics.
abstract: Immersion induces air trapping in the lungs, as does asthma. Consequently, when using diving apparatus, asthmatics may face greater risk than non-asthmatics of pulmonary barotrauma (PBT) during ascent. We studied the pulmonary airflows and closing capacities (CC = closing volume + residual volume) in subjects with exercise-induced asthma (A, n = 12) and in healthy controls (C, n = 11) under four conditions: dry and immersed, both before and after exercise (treadmill running, non-immersed). Immersed, both C and A had significant and equivalent reductions in vital capacity, FEV1, FEV1/FVC, and FEF25%-75%. Post-exercise and immersed, pulmonary airflows deteriorated further in A but were better in C: FEV1 (A, 3.6 +/- 0.8 liter vs. 3.3 +/- 0.8 liter, P = 0.001; C, 3.9 +/- 0.5 liter vs. 4.1 +/- 0.6 liter, P = 0.006), FEF25-75% (A, 3.5 +/- 1.0 liter x s(-1) vs. 3.0 +/- 0.8 liter x s(-1). P < 0.05; C, 4.0 +/- 0.9 liter x s(-1) vs. 4.3 +/- 0.9 liter x s(-1), P < 0.05). Therefore, in contrast to C, A subjects had reduced pulmonary airflows during immersion after exercise. Furthermore, A subjects more often had no closing volume phase IV when immersed after exercise than C (P = 0.005). Interpreting the absence of phase IV as indicative of more air trapping in the asthmatics during immersion after exercise would be consistent with the reductions in airflow.
authors.affiliation: Center for Research and Education in Special Environments, Department of Physiology and Biophysics, State University of New York at Buffalo, USA.
authors.forename: J J
authors.initials: JJ
authors.lastname: Leddy
authors.forename: A
authors.initials: A
authors.lastname: Roberts
authors.forename: J
authors.initials: J
authors.lastname: Moalem
authors.forename: T
authors.initials: T
authors.lastname: Curry
authors.forename: C E
authors.initials: CE
authors.lastname: Lundgren
mesh_terms: D000328:Adult; D000704:Analysis of Variance; D001250:Asthma, Exercise-Induced / Q000503:physiopathology*; D016022:Case-Control Studies; D005260:Female; D005540:Forced Expiratory Flow Rates; D005541:Forced Expiratory Volume; D006801:Humans; D007101:Immersion / Q000503:physiopathology*; D008168:Lung / Q000503:physiopathology*; D008297:Male; D011187:Posture; D012119:Respiration; D014797:Vital Capacity