A randomized cross-over study of auto-continuous positive airway pressure versus fixed-continuous positive airway...

To compare the efficacy of auto-CPAP (AutoSet Spirit, ResMed) versus fixed-CPAP (S6 Elite, ResMed) in improving daytime sleepiness, health status, objective compliance and the ultimate treatment preference in patients with severe OSA.

The study recruited 43 subjects aged 18-65 years with newly diagnosed severe OSA (AHI >30/h). Patients were initially treated with either auto-CPAP or fixed-CPAP for 2 months and then crossed over after a washout period of 1 week for another 2 months.

The study was completed by 41 patients. Results are presented as mean (SE). Use of auto-CPAP in the first and the second month was significantly higher than that of fixed-CPAP [129.7 (9.9) and 130.5 (10.7) h vs 115.2 (9.5) and 113.2 (9.4) h, P = 0.04 and 0.01], whereas mean hourly use per night was 4.3 and 4.4 h versus 3.8 and 3.7 h, respectively. The Epworth sleepiness scores improved after 1 month in both treatments (13.4 to 8.5 and 8.2, P < 0.01 for both). The Sleep apnoea quality of life index improved in the first month in both compared with baseline [4.6 (0.2) to 5.0 (0.2) for auto-CPAP and 4.9 (0.2) for fixed-CPAP, P = 0.01 and 0.04, respectively], with no difference between the two treatments. Nine and 30 patients preferred auto-CPAP and fixed-CPAP, respectively, at the end of the trial, whereas 14 and 25 patients would have chosen the same treatments if cost had not been a consideration.

Auto-CPAP and fixed-CPAP were equally effective in improving symptoms and health status in patients with severe OSA. Usage was higher with auto-CPAP, but more patients ultimately chose fixed-CPAP.