Impact of gas masks on work of breathing, breathing patterns, and gas exchange in healthy subjects

Abstract

BACKGROUND: The gas mask is used to protect military and non-military personnel exposed to respiratory hazards (chemical, biologic, radiologic, and nuclear agents). The objective was to evaluate the impact of the gas mask on indexes of respiratory effort and breathing patterns in a human model because no data exist. METHODS: The design of the study was a crossover evaluation with four 10-min conditions in a randomized order: with and without wearing the gas mask when at rest and when exerting a standardized effort. During the studied conditions, 14 healthy subjects were evaluated for breathing patterns, indexes of respiratory effort (work of breathing, pressure-time product for esophageal pressure, and esophageal pressure swing) and capillary blood gases. Continuous SpO2 was recorded during the tested conditions. RESULTS: The indexes of respiratory effort significantly increased when subjects wore the gas mask under the tested conditions (at rest and during effort). The work of breathing was significantly augmented with the mask (at rest, 0.40 = 0.32 J/cycle vs 0.25 = 0.10 J/cycle; effort, 5.96 = 3.32 J/cycle vs 4.43 = 2.50 J/cycle; P