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 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. DESIGN: 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. 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 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.

Long-term efficacy of fixed CPAP recommended by Autoset for OSAS.

The Autoset autotitration system (Resmed, Australia) was designed as an aid for determination of the effective level of CPAP. Two studies have shown that the 95% pressure centile during a night with Autoset, after excluding any periods with severe leak (P95), was well correlated with the pressure determined manually according to the reference method. However, the suitability of P95 under Autoset for treatment with conventional CPAP needed to be evaluated outside of the context of titration. The objective of this study was to measure the compliance and efficacy of CPAP at P95 determined by Autoset, after 3 months. Twenty-four patients who had undergone routine autotitration by Autoset under polysomnographic control in the laboratory for previously untreated OSAS were evaluated after 3 months of treatment with CPAP at P95. This evaluation was based on compliance, daily usage, determined by reading the hourly counter, Epworth sleepiness score and home respiratory recording under CPAP. Polysomnography under Autoset showed a significant reduction of abnormal respiratory events (apnea-hypopnea index (AHI): 5.7 (+/-4.6) vs 69.6 (+/-29.8) n/h; p<0.001). P95 was between 8.5 and 15 cm H2O (mean: 11.2 (+/-1.6)). Two patients were lost to follow-up. At 3 months, 18 out of 22 (82%) patients declared that they were still using their machine with a daily usage of 5.25 (+/-1.82) h. The Epworth sleepiness scale was significantly decreased (5 (+/-4.1) vs 11.4 (+/-5.4); p<0.05). P95 recommended by Autoset remained effective on abnormal respiratory events with a low AHI (4.1 (+/-3.2) n/h) and a low 4% oxygen desaturation index (3.6 (+/-4.5) n/h) under CPAP. This study confirms the efficacy of autotitration and the suitability of P95 determined by Autoset for long-term treatment by conventional CPAP at home.