Heated humidification or face mask to prevent upper airway dryness during continuous positive airway pressure therapy

Study objectives: The objectives of this study were (1) to evaluate the way in which nasal continuous positive airway pressure (CPAP) therapy influenc es the relative humidity (rH) of inspired air; and (2) to assess the impact on rH of the addition of an integrated heated humidifier or a full face ma sk to the CPAP circuitry. Design: The studies were performed in 25 patients with obstructive sleep ap nea syndrome receiving long-term nasal CPAP therapy and complaining of nasa l discomfort. During CPAP administration, temperature and rH were measured in the mask either during a night's sleep for 8 patients or during a day ti me study in which the effects of mouth leaks were simulated in 17 patients fitted with either a nasal mask (with or without humidification) or a face mask alone, Setting: University hospital sleep disorders center. Measurements and results: Compared with the values obtained with CPAP alone , integrated heated humidification significantly, increased rH during the s leep recording, both when the mouth was closed (60 +/- 14% to 81 +/- 14%, p < 0.01) and during mouth leaks (43 +/- 12% to 64 +/- 8%, p < 0.01), During the dal-time study, a significant decrease in rH was observed with Cp,yp a lone. Compared with the values measured during spontaneous breathing withou t CP;UP (80 +/- 2%), the mean rH was 63 +/- 9% (p < 0.01) with the mouth cl osed and 39 +/- 9% (p < 0.01) with the mouth open, The addition of heated h umidification to CP;IP prevented rH changes when the mouth was closed (82 /- 12%), but did not fully prevent the rH decrease during simulation of mou th leaks (63 +/- 9%) compared with the control period (80 +/- 2%, p < 0.01) , Finally, attachment of a face mask to the CPAP circuitry prevented rH cha nges both with the mouth;th closed (82 +/- 9%) and with the mouth open (84 +/- 8%), Conclusions: These data indicate that inhaled air dryness during CPAP thera py can be significantly attenuated by heated humidification, even during mo uth leaks, and cart be totally prevented by using a face mask.