In general, central sleep apnea is not as common as obstructive sleep apnea but it is common in patients with heart failure. It has been repeatedly shown that central sleep apnea worsens the prognosis of heart failure. The current concept in the development of CSA is hypocapnia which causes temporary cessation of respiratory neural output. Different methods for supplement of CO2 have been used to eliminate CSA. However, variation of CO2 concentration during overnight treatment and tight-fitting mask made the treatment uncomfortable. It is important to develop a device with a comfortable mask to supply constant low dose CO2 without breathing difficulty. We recently developed a device for treatment of CSA.

Objective: To determine whether the device could improve sleep quality while eliminating CSA during the overnight study. Methods: Patients with central sleep apnea diagnosed by diaphragm EMG will be recruited in this study. CO2 concentration for treatment would be manually titrated during overnight PSG. Patients were then treated with an effective lowest concentration of CO2 derived from titration under PSG on the third night. The sleep apnea hypopnea index (AHI), central sleep apnea index (CHI), arousal index (ArI), Oxygen desaturation index (ODI), sleep structure, blood pressure, heart rate, diaphragm EMG, treatment side effects and treatment preference were to be observed.

Inclusion Criteria:

1. Willing to participate after informed consent
2. Males and females, any race and aged≥18yeras
3. Objectively confirmed central sleep apnea/Cheyne Stokes Respiration with an apnoea-hypopnoea- index (AHI)≥5/h by overnight polysomnography

Exclusion Criteria:

1. Obstructive sleep apnea
2. Severe COPD，FEV1/FVC<70% and FEV1<60%
3. Chronic CO2 retention with unknown reason
4. Severe nasal congestion
5. Poor understanding