The Gas Mask: the Effects on Respiration!

"We have been evaluating breathing patterns, index of respiratory efforts and blood gases in all randomized conditions. A gas mask has been used mask (C4, Airboss Defence, Bromont, Canada).~Airway pressure, inspiratory and expiratory flows have been measured. An esophageal catheter has been introduced at the beginning of the study to measure esophageal pressure (Peso) and calculate indexes of respiratory effort (PTPeso, WOB). SpO2 has been continuously measured and capillary blood bases were drawn at the end of each condition. Each condition lasted 10 minutes, data of the last 2 minutes at a steady state has been considered for analyses."

During the conditions that involved a gas mask, the measurement of the work of breathing is achieved with a oesophageal catheter and two disposable pneumotachs. While the oesophageal catheter has been fixed to the mandibular with an hypo-allergic tape, the two pneumotachs are hooked respectively on the canister and exhalation port of the gas mask. Investigators have induced the hypoxemia with a mixture nitreous and medical gas in a plastic bag that has been setted up to the canister. The FiO2 level has been kept to 14 percent.