title: Heated humidification or face mask to prevent upper airway dryness during continuous positive airway pressure therapy.
abstract: OBJECTIVE
  The objectives of this study were (1) to evaluate the way in which nasal continuous positive airway pressure (CPAP) therapy influences 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 mask to the CPAP circuitry.
  
  
  METHODS
  The studies were performed in 25 patients with obstructive sleep apnea syndrome receiving long-term nasal CPAP therapy and complaining of nasal discomfort. During CPAP administration, temperature and rH were measured in the mask either during a night's sleep for 8 patients or during a daytime 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.
  
  
  METHODS
  University hospital sleep disorders center.
  
  
  RESULTS
  Compared with the values obtained with CPAP alone, integrated heated humidification significantly increased rH during the sleep 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 daytime study, a significant decrease in rH was observed with CPAP alone. Compared with the values measured during spontaneous breathing without CPAP (80 +/- 2%), the mean rH was 63 +/- 9% (p < 0.01) with the mouth closed and 39 +/- 9% (p < 0. 01) with the mouth open. The addition of heated humidification to CPAP prevented rH changes when the mouth was closed (82 +/- 12%), but did not fully prevent the rH decrease during simulation of mouth 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 changes both with the mouth closed (82 +/- 9%) and with the mouth open (84 +/- 8%).
  
  
  CONCLUSIONS
  These data indicate that inhaled air dryness during CPAP therapy can be significantly attenuated by heated humidification, even during mouth leaks, and can be totally prevented by using a face mask.
authors.affiliation: Physiological Sciences Graduate Program, Biomedical Center, Federal University of Espirito Santo, Vitoria, ES, Brazil.
authors.forename: M T
authors.initials: MT
authors.lastname: Martins De Araújo
authors.forename: S B
authors.initials: SB
authors.lastname: Vieira
authors.forename: E C
authors.initials: EC
authors.lastname: Vasquez
authors.forename: B
authors.initials: B
authors.lastname: Fleury
mesh_terms: D002940:Circadian Rhythm; D005145:Face; D006358:Hot Temperature; D006801:Humans; D006813:Humidity; D008397:Masks; D008875:Middle Aged; D009297:Nasal Mucosa / Q000473:pathology; D009668:Nose Diseases / Q000209:etiology / Q000517:prevention & control*; D011175:Positive-Pressure Respiration / Q000009:adverse effects*; D020181:Sleep Apnea, Obstructive / Q000628:therapy*; D016896:Treatment Outcome