Fig. 3.
Upper panels show absolute humidity, relative humidity and temperature in the four study steps. Boxes indicate median [interquartile range] values, whiskers indicate minimum and maximum values. Dotted line in the absolute humidity panel marks the threshold of 15 mgH2O/L that has been indicated as the lowest humidity value to avoid discomfort during facemask NIV and CPAP [16]. When no external gas conditioning was applied (NoH step) both temperature and humidity were lower, albeit median absolute humidity was above 15 mgH2O/L, the 25th percentile being 12 mgH2O/L (i.e., most patients received an adequate level of humidification). Lower panels show VAS dyspnea, VAS discomfort and subjective observator-assessed fog effect (on a scale from 1 to 3) in the four steps (black circles indicate median value, range indicates interquartile range). Discomfort and fog effect were lowest in the NoH step