Fig. 2

Comparison of cuff pressures with and without lubrication under continuous flushing with nitrous oxide. Black and red bars in Graph a represent polyvinyl chloride (PVC) cuffs with lubrication and PVC cuffs without lubrication under continuous flushing with N₂O. Gray and blue bars in Graph b represent polyurethane (PU) cuffs with lubrication and PU cuffs without lubrication under continuous flushing with N₂O. Cuff pressure was recorded at 0 min (baseline), 20 min, 40 min, and 60 min of nitrous oxide exposure. # P < 0.05, ## P < 0.01, and ### P < 0.0001 relative to the baseline (0 min) pressure at each time point. ** P < 0.001 and *** P < 0.0001 in the post hoc comparisons between 2 groups at each time point. P-values < 0.0167 (0.05/3) were considered statistically significant in the post hoc comparison of 2 groups at each time point. Data are expressed as mean (SD)