Obstructive Sleep Apnea Syndrome (OSAS) is a common condition that leads to daytime sleepiness and loss of vigilance and, in addition, increased risk of cardiovascular events. The most effective treatment consists in ventilation by mask with continuous positive airway pressure (CPAP), that prevents collapse of the upper airway. However the degree of collapsibility of the pharynx may vary in relation to position, sleep stage, or alcohol or sedative consumption. Thus, CPAP treatment (invented in 1981) has evolved with the development of more sophisticated equipment that permits adapted variations in pressure levels (autoCPAP) with the objective adjusted pressure to avoid airways obstruction with minimal pressure.

Different models of autoCPAP function with different signals and event detection algorithms with different modes of reaction to events. These machines are marketed with CE certification, that guarantees electrical security, but there is to date, no requirement for pre-marketing clinical validation. Nonetheless inadequate treatment may leave patients at risk of accidents and cardiovascular events. These machines can be bench tested using test equipment that can measure with accuracy the response to simulated events, but the testing equipment cannot simulate the diversity of clinical situations, nor the residual level of microarousals that may persist. Thus these bench tests need to be supplemented by clinical studies. The investigators objective is to test the efficacy of these machines on residual sleep-related events during a one night autotitration polysomnography. We develop a prospective, multicentre, non randomised study with autotitration polysomnography only for one night. These clinical results will be compared with the results of bench tests in order to evaluate the pertinence of the bench tests and their eventual utility to simplify clinical evaluation. The perspective of developing a reliable testing protocol may eventually play a role in the certification of these machines.

Inclusion Criteria:

• Patients with obstructive sleep apnea syndrome and indication for autoPPC

Exclusion Criteria:

• Patients with COPD, or evolutive heart disease Patients with evolutive cancer Patients already with PPC machine Patients simultaneously included in another clinical study.