[Expiratory pressure reduction (C-Flex Method) versus fix CPAP in the therapy for obstructive sleep apnoea].

Introduction: The REM star C-Flex (Fa. Respironics) was introduced in 2003. In contrast to the conventionel fix CPAP mode, the C-Flex mode is characterised by a pressure reduction at the beginning of expiration. In a randomised cross-over design, we investigated if this C-Flex-mode has advantages compared to the fix CPAP mode in terms of treatment quality and patient satisfaction.

Methods: In this prospective randomised single-blinded cross-over study we investigated 20 patients with obstructive sleep apnoea treated with fix CPAP versus treatment with the C-Flex mode (level 2) for 6 weeks, respectively. We compared the polysomnographically measured quality of treatment and the subjective satisfaction of either form of therapy. Additionally, we measured long-term compliance of the C-Flex therapy in a 3-year follow-up with the integrated counter of the C-Flex devices.

Results: The mean levels of pressure of the fix CPAP and the C-Flex therapies were 8.4 +/- 2.9 mbar in both groups. There was an identical quality of treatment in terms of respiratory events, arousal index, slow wave sleep and Epworth sleepiness scale. The compliance of nocturnal use of the C-Flex and the fix CPAP was identical (6.0 +/- 0.67 C-Flex use vs. 5.8 +/- 0.98 CPAP use [h/night]). The subjective satisfaction was higher in the C-Flex mode at the end of the study since 18 of 20 patients (90%) subjectively prefered the C-Flex mode because of the easier expiration. 19 patients received a C-Flex device for long-term therapy. The 3-year-follow-up showed a regular utilisation of the C-Flex by 16 of 19 (84.2%) of these patients (mean nocturnal use 6.0 +/- 0.9 h/night). 3 of the 19 patients (15.8%) did not use their C-Flex regulary. None of the patients has terminated therapy completely.

Conclusion: C-Flex mode and the conventional fix CPAP therapies show an equivalent treatment quality according to polysomnographic data. The expiratory pressure reduction compared to conventional CPAP was felt to be more comfortable by 90% of patients. The long-term-compliance as measured by regular use of the C-Flex device was 84.2% (16 out of 19 patients) after 3 years, these numbers are higher than published data on compliance with conventional CPAP therapy.