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Updated: Jul 16, 2026
Investigation into Deep Breathing through Measurement of Ventilatory Parameters and Observation of Breathing Patterns
Published on: September 16, 2019
The bronchoprotective effect of deep inspiration is flow rate dependent
Gwen S Skloot1, Dipak Chandy, Neil Schachter
1Division of Pulmonary and Critical Care Medicine, Department of Medicine, The Mount Sinai School of Medicine, New York, NY 10029, USA. gwen.skloot@mssm.edu
Background And Study Objective:
Deep inspiration (DI) protects against methacholine-induced bronchoconstriction in healthy subjects. We hypothesized that this bronchoprotective effect of DI depends upon the inspiratory flow rate.
Design:
Prospective, controlled study.
Setting:
Pulmonary function laboratory within a large tertiary medical center.
Participants:
Ten healthy nonsmokers without asthma or rhinitis.
Measurements:
First, we performed a methacholine challenge in the absence of DI to determine the concentration sufficient to reduce FEV(1) by 20%. On two subsequent days, the challenge was repeated with the addition of either a fast or slow DI immediately before the threshold concentration of methacholine. We calculated the % reduction in FEV(1) and FVC from baseline.
Results:
Mean % reduction in FEV(1) and FVC was significantly less with a fast DI than with no DI (20+/-3% vs. 34+/-4% for FEV(1), p=0.02; 12+/-3% vs. 23+/-3% for FVC, p=0.03); slow DIs did not significantly affect the methacholine-induced reduction in lung function.
Conclusion:
A fast DI is bronchoprotective while a slow DI is not. Elucidating the conditions that maximize or alternatively, eliminate bronchoprotection in healthy subjects may ultimately provide insight into the pathophysiology of asthma.
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