Ventilation index during exercise under 3 conditions
 surgical maskurethane maskno maskp value
Ti (sec)1.02±0.180.92±0.160.85±0.160.001
RR (rate/min)30.44±6.8232.41±6.7634.28±7.470.01
ETCO2 (%)6.58±0.496.42±0.466.30±0.530.001
VE/VO226.21±2.9027.53±2.7528.22±3.290.05