RT Journal Article SR Electronic T1 Hygrometric properties of inspired gas and oral dryness in patients with acute respiratory failure during noninvasive ventilation JF Respiratory Care FD American Association for Respiratory Care SP respcare.02351 DO 10.4187/respcare.02351 A1 Jun Oto A1 Emiko Nakataki A1 Nao Okuda A1 Mutsuo Onodera A1 Hideaki Imanaka A1 Masaji Nishimura YR 2013 UL http://rc.rcjournal.com/content/early/2013/06/13/respcare.02351.abstract AB Purpose: Because noninvasive ventilation (NIV) delivers medical gas at high flow, inadequate humidification may cause oral dryness and patient discomfort. A heated humidifier (HH) is often used to humidify inspired gas during NIV but little has been reported about its effects on hygrometric conditions inside of full face masks and oral dryness for a 24 hrs use. Methods: Using a hygrometer, we measured absolute humidity (AH) of inside full face masks applied to patients with acute respiratory failure who were receiving NIV for 24 hrs. A single limb turbine ventilator and a facemask with an exhalation port were used for NIV. Oral moistness was evaluated using an oral moisture-checking device and, three times during the study, patients subjectively scored feeling of dryness on a 0–10 numerical rating scale (NRS; 10 was the most severe dryness). Results: Sixteen patients with acute respiratory failure were enrolled. Full face mask internal AH was 30.0±2.6 mgH2O/L (range 23.1–33.3 mgH2O/L). The median value of oral moistness was 19.2% (inter-quartile range: IQR 4.4%–24.0%) and the median value of NRS was 5.5 (IQR 4–7). AH and inspired gas leak correlated inversely within the patients (correlation coefficient: r = −0.56, p < .001) and between the patients (r = −0.58, p = .02). AH and oral moistness correlated within the patients (r = 0.39, p = .04) Oral breathing was associated with reduced oral moistness (p = .001) and increased NRS (p = .002). Conclusions: AH varied among patients and some complained of oral dryness even with HH. Oral breathing decreased oral moistness and worsened feelings of dryness.