Mean values (standard deviations) of physiological and pulmonary function variables measured when wearing prototype respirators.

SpO2 (pulse oximetry-derived oxygen saturation; tcPCO2 (partial pressure of transcutaneous carbon dioxide); HR (heart rate); RR (respiratory rate); VO2 (volume of oxygen utilization); VCO2 (volume of carbon dioxide production); VE (minute ventilation); VT (tidal volume); TTymp (tympanic temperature). * significant time effect. ¶ indicates the point at which the PR was donned