Physiological variables
Wearing an N95 respirator for 4-hour shift was associated with a significant decrease in PH [7.35mmHg (7.32,7.37) at baseline vs. 7.34mmHg (7.32,7.35) at 4 hours, P=0.02] and PvO2[23.2 mmHg (18.2,34.5) at baseline vs. 18.6 mmHg (14.6, 23.8) at 4 hours, P<0.001]. The change in PCO2[49.5mmHg (44.9, 53.1) at baseline vs. 50.5mmHg (47.1, 56.9) at 4 hours, P=0.22] or bicarbonate [26.2mEq/L (25.3, 28.6) at baseline vs. 26.6mEq/L (24.5, 28.7) at 4 hours, P=0.53)] did not reach statistical significance. Results are summarized in Figure 1. There was no significant change in HR or oxygen saturation. Median EtCO2 under normal unmasked conditions and at 4 hours was 32.5mmHg (29.8, 35) vs. 38.5mmHg (34, 41), respectively (p<0.0001).