The effects of nasal continuous positive airway pressure on vascular functions and serum cardiovascular risk factors in obstructive sleep apnea syndrome

We investigated whether the nasal continuous positive airway pressure (nCPAP) could have impacts on impaired vascular functions and serum cardiovascular risk factors in obstructive sleep apnea syndrome (OSAS). We enrolled 25 OSAS patients of moderate to severe degree. After polysomnography, carotid-femoral pulse wave velocity (cfPWV) and flow-mediated dilation (FMD) were measured. Also, serum levels of C-reactive protein (CRP), total cholesterol, triglyceride, high-density lipoprotein (HDL) cholesterol, glucose, and insulin were measured. After nCPAP treatment (mean duration, 138.7 +/- 42.6 days), these tests were performed again. The mean apnea hypopnea index prior to nCPAP was 64.9 +/- 20.0/h, which decreased to 4.1 +/- 2.0/h with nCPAP (p < 0.001). After nCPAP, cfPWV (m/s) decreased from 11.2 +/- 4.5 to 9.3 +/- 2.1 (p = 0.031), and FMD (%) was improved from 5.52 +/- 2.49 to 6.58 +/- 2.50 (p = 0.006). Body mass index, serum levels of CRP, total cholesterol, triglyceride, HDL cholesterol, or glucose did not change after nCPAP. Insulin resistance was not improved either. The cfPWV and FMD were significantly improved after nCPAP treatment, even though there was no significant change in body weight or serum cardiovascular risk factors. The nCPAP treatment could decrease risks of cardiovascular complications in OSAS patients through improving vascular functions.