The CPAP Effect in Severe Obstructive- Sleep- Apnea Patients Without Daytime Sleepiness: A Control Randomized Trial

Specific Aim: 1. To prove our hypothesis that in severe OSA patients without daytime sleepiness, CPAP worked as effectively as in severe OSA patients with daytime sleepiness. Using sham CPAP as the optimal placebo, we conduct a randomized double-blind placebo controlled trial to assess the CPAP effect in severe OSA patients without daytime sleepiness. 2. To establish a model to predict the CPAP effect We use the parameters of five aspects, including changes of polysomnographic parameters, improvement of sleepiness, fatigue and QOL, sympathetic activity, inflammatory mediators and metabolism, to establish a model to predict CPAP effect.