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Table 1 Changes in respiratory parameters of pregnant subjects breathing through N95 masks compared to controls breathing ambient air

From: Respiratory consequences of N95-type Mask usage in pregnant healthcare workers—a controlled clinical study

N95 Mask vs Control Mean difference SE (95 % CI) P value
Pre exercise rest period
 VO2 −0.40 0.30 (−1.02, 0.23) 0.20
 VCO2 −0.04 0.02 (−0.07, −0.003) 0.035
 Tidal volume −0.15 0.04 (−0.23, −0.08) < 0.001
 Breathing frequency 0.31 0.69 (−1.13, 1.75) 0.66
 Minute ventilation −2.23 0.66 (−3.60, −0.85) 0.003
 FeO2 −0.52 0.97 (−0.79, −0.25) 0.001
 FeCO2 0.25 0.07 (0.11, 0.40) 0.002
 Fi O2 −0.02 0.07 (−0.16, 0.12) 0.76
 Fi CO2 −0.01 0.01 (−0.03, 0.01) 0.47
Exercise period
 VO2 −1.30 0.47 (−2.3, −0.31) 0.01
 VCO2 −0.10 0.25 (−0.15, −0.05) 0.001
 Tidal volume −0.21 0.05 (−0.32, −0.11) < 0.001
 Breathing frequency −0.51 0.67 (−1.92, 0.89) 0.45
 Minute ventilation −5.55 0.97 (−7.58, −3.51) < 0.001
 FeO2 −0.54 0.08 (−0.70, −0.38) < 0.001
 FeCO2 0.30 0.06 (0.18, 0.42) < 0.001
 Fi O2 0.02 0.08 (−0.13, 0.17) 0.81
 Fi CO2 0.004 0.01 (−0.23, 0.03) 0.75
Post exercise rest period
 VO2 −0.22 0.21 (−0.67, 0.23) 0.32
 VCO2 −0.01 0.01 (−0.04, 0.01) 0.29
 Tidal volume −0.08 0.03 (−0.14; −0.01) 0.02
 Breathing frequency 0.48 0.50 (−0.56, 1.53) 0.34
 Minute ventilation −1.10 0.47 (−2.10, −0.11) 0.031
 FeO2 −0.30 0.09 (−0.49, −0.11) 0.004
 FeCO2 0.19 0.05 (0.09, 0.29) 0.001
 Fi O2 −0.03 0.09 (−0.2, 0.16) 0.77
 Fi CO2 0.00 0.02 (−0.03, 0.03) 0.99
  1. (bolded values: statistically significant)