At rest and effort, what would be the impacts for the work of breathing and gas exchange? In order to avoid hypoxemia and hyperoxia, what would be the optimal means to restore proper oxygenation? We hypothesised: i. The gas mask design and its components may lead to these respiratory load issues. Consequently, gas masks are usually studied separately from other respirators and Self-Contained Breathing Apparatus (SBCA). Conventionally, the military gas mask covers a large spectrum of protection aspects and matched with their specific canisters. The military gas mask is part of the respirator classification but owes its specific features. That originated from Dr Cluny Macpherson's initiatives whom was a Canadian military physician.
The current technology of a gas mask has been used to protect the respiratory system as far back as the First World War. The principal way of penetration of CBRNE agents is the respiratory system. Other: measurement of the work of breathing Device: Gas mask Our results and method may be used as a reference for evaluating tolerance with different designs of gas masks. This study is the first to directly assess the indexes of efforts with esophageal pressure in this situation. Conclusions: This study demonstrated an increase of the indexes of respiratory effort during an exercise with the gas mask.
This may explain in part the increased work of breathing with masks. We measured on bench the inspiratory and expiratory resistances of the tested gas mask (C4: inspiratory resistances = 3.2 cmH2O at 1 L/sec expiratory resistances = 0.9 cmH2O at 1 L/sec). Data for induced hypoxemia are under analysis. There was no difference for the breathing pattern and arterial blood gases data with and without mask. During the effort, the respiratory index increased (WOB 4.0☒.6 vs. At rest, in 8 out of 10 healthy subject the indexes of effort were higher with the gas mask, a statistical trend was observed with the WOB (0.22☐.13 vs. Comparing the wearing of the gas mask and without, most of the respiratory index increased in the tested conditions (at rest, during induced hypoxemia and during effort). Results: The preliminary analyses based on 10 subjects are presented here. Each condition lasted 10 minutes, data of the last 2 minutes at a steady state were considered for analyses. SpO2 was continuously measured and capillary blood bases were drawn at the end of each condition. An esophageal catheter was introduced at the beginning of the study to measure esophageal pressure (Peso) and calculate indexes of respiratory effort (PTPeso, WOB). Airway pressure, inspiratory and expiratory flows were measured. Seven conditions have been tested in a randomized order: at rest, during effort (on a tread mill, standardized at 7 METs for all subjects) and during induced hypoxemia with and without a mask (C4, Airboss Defence, Bromont, Canada). Methods: We are completing our study with 14 healthy subjects to evaluate breathing patterns, index of respiratory efforts and blood gases.
The aim of the study was to evaluate the impact of the gas mask on respiratory patterns and indexes of the respiratory effort.
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