The prevalence of OSA (Obstructive sleep apnea，OSA) is 2%-4% in general population and 16%-47% in surgical-heart failure patients. Our previous study found that OSA was associated with the increasing incidence of perioperative adverse events.The continuous positive airway pressure (CPAP), as the standard treatment for OSA, is extensively applied clinically. The previous study reported that postoperative AHI was reduced and SPO2 was increased by CPAP treatment. However, whether CPAP treatment can improve OSA postoperative and related adverse events or not in patients with rheumatic valvular heart diseases (RVHD) were not reported.The purpose of this study is to observe the effective of preoperative CPAP on postoperative sleep parameters and adverse events, such as AHI changes, duration of ICU stay and duration of mechanical ventilation.

Between December 1, 2017 and June 30 2019, 200 patients with chronic heart failure caused by rheumatic valvular heart disease waiting for heart valve replacement in Department of Cardiovascular Surgery were screened for obstructive sleep apnea (OSA) by full-night polysomnography (PSG). Of them, 30 OSA patients were enrolled and randomly received CPAP treatment and non-CPAP treatment (15:15).

The CPAP treatment group received both baseline and CPAP treatment. The full-night CPAP treatment was conducted from 21:00 pm to 6:00 am for 7 days preoperatively. The non-CPAP treatment group received baseline treatment.

Preoperative Sleep parameters (AHI, mean and lowest SPO2) and clinical evaluations including NYHA class, electrocardiographic, echocardiographic, arterial blood gas analysis findings, baseline medication, and 6-minute walk test were recorded.

Operation related parameters such as duration of operation, duration of cardiopulmonary bypass and bleeding volume were recorded.

Postoperative adverse events such as duration of ICU stay, postoperative duration of mechanical ventilation, pacemaker use, complicated infection and reintubation are recorded.

A PSG was re-examined before discharge from hospital. The changes of AHI, mean and lowest SPO2 between pre- and post-operative PSG parameters were calculated.

The operation related parameters, postoperative adverse events and the changes of sleep parameters were compared between CPAP and non-CPAP patients.

Inclusion Criteria:

1. Patients aged 18-75 years.
2. Patients with rheumatic valvular heart disease.
3. Patients combined with obstructive sleep apnea (apnea-hypopnea index >=5/h).
4. Received heart valve replacement surgery.
5. The enrolled patients having received patients' informed consent.

Exclusion Criteria:

1. History of stroke or clinical signs of peripheral or central nervous system disorders.
2. History of Chronic obstructive pulmonary disease or asthma.
3. Enrolment in another clinical study.

The individual participant data will not be shared. The informed consent will be ansigned before enrolled in the study and ensured to keep personal information confidential.