Obstructive sleep apnea (OSA) is a situation of repetitive upper airway obstruction during sleep. For patients with severe OSA, continuous positive airway pressure (CPAP) therapy was the standard therapy, especially those with daytime sleepiness and cardiovascular comorbidities. Although CPAP is effective in OSA treatment, the poor adherence due to high pressure was often reported. Instead, oral appliance (OA) was the alternative for those who could not tolerance CPAP or mild to moderate OSA. Oral appliance was less effective in compared with CPAP, but OA is more tolerable and acceptable in OSA patients.

Only one observation study addressed the effects of the combinations of OA and CPAP in OSA patients . The pilot study displayed combination therapy of CPAP and OA is effective in OSA patients and could decrease CPAP pressure. However, the study enrolled the patients with CPAP intolerance according to the subjective chief complaint, not the objective CPAP pressure data. In the present study, we studied the effects of combinations of CPAP and OA for patients with severe OSA who could not tolerate CPAP with high-pressure setting.

This is a prospective study in a tertiary teaching hospital, National Taiwan University Hospital. Patients are eligible with age ≧ 20 years old, severe OSA [apnea-hyponea index (AHI) >= 30/hr] who could not tolerate CPAP pressure >15 cmH2O, determined by manual titration (first titration) and willing to use OA.

The study designed was found out the patients with severe OSA (AHI >= 30/hr ). With first titration, the investigators excluded the severe OSA patients using CPAP (CPAP pressure < 15 cmH2O) and could tolerate CPAP. Those patients who could not tolerance CPAP high pressure setting started a three-month oral appliance trial. Then, the investigators repeated the full-channel polysomnography (PSG) with second titration on those with residual AHI ≧ 10/hr while patients were on OA. Therefore, those patients treated with combinations of OA and CPAP for three months and then repeated the PSG. The washout period in each therapy was two weeks. The total follow-up period is about 6 months after enrolled.

The investigators collected the demographic data from medical records and PSG data, including age, gender, body mass index (BMI), CPAP titration, AHI, total sleep time, oxygen desaturation, and arousal index…et al.

Our primary end point is the changes in AHI compared with combination therapy, and OA use. The secondary end points are the difference in titrated CPAP pressure, BMI, blood pressure, and daytime sleepiness compared with combination therapy and OA use.

Statistics analysis Data are presented as mean ± standard deviation (SD). Continuous variables were tested by paired Student's t test in group comparisons. Statistical significance was assumed when a null hypothesis could be rejected at p<0.05. The investigators compared the difference between combination therapy, OA, and baseline by ANOVA, repeated measure. Statistical analysis was done using the SPSS 22.0 for Windows.

Inclusion Criteria:

1. New diagnosed obstructive sleep apnea patients older than 20 years old
2. AHI more than 30/hr with moderate to severe obstructive sleep apnea
3. Willing to accept CPAP and OA treatment

Exclusion Criteria:

1. nasal problems causing CPAP intolerance
2. status post uvulopalatopharyngoplasty
3. alcohol abuse and dependence
4. life expectancy less than 6 months
5. severe cardiopulmonary distress.