Mask leakage in continuous positive airway pressure and C-Flex

Many patients with obstructive sleep apnea syndrome (OSAS) receiving continuous positive airway pressure (CPAP) complain of leaky masks or too high pressure during expiration. C-Flex is a breathing mode with a constant CPAP pressure during inspiration and a reduced pressure during expiration. We compared the leakage data between CPAP and C-Flex and their influence on patients' compliance. Thirty patients (22 men, 8 women, aged 55.4 +/- 11.7 yr, BMI 32.0 +/- 7.4 kg/m(2)) with polysomnographically diagnosed OSAS got a CPAP or C-Flex therapy in a randomized double-blind and cross-over design. After 6 weeks, an adjustment to the other mode followed. Leakage data were sampled during all polysomnographic examinations. Twelve patients dropped out of the study (7 after C-Flex, 5 after CPAP), 4 of them gave up CPAP therapy completely (2 after CPAP, 2 after C-Flex). The leakage in CPAP mode was 27.5 +/-11.5 l/min and in C-Flex mode 28.0 +/-10 l/min (ns). The average nightly use in CPAP mode was 350.0 +/- 70.2 min and in C-Flex mode 347.0 +/- 70.8 min (ns). In the final decision of therapy, 9 patients chose C-Flex and 4 patients CPAP (P=0.001). Five patients had no preference regarding the therapy mode. There is no difference in leakage and compliance between CPAP and C-Flex. But significantly more patients decided for a therapy with the C-Flex mode. There must be other unknown factors that influence the decision for the mode of therapy.