Cerebral hemodynamic changes in obstructive sleep apnea syndrome after continuous positive airway pressure treatment

Patients with obstructive sleep apnea syndrome (OSAS) are at increased risk for cerebrovascular diseases. The underlying mechanisms remain obscure. It may occur through a reduction in cerebral vascular reactivity. Continuous positive airway pressure (CPAP) is effective in reducing the occurrence of apneas. We hypothesized that treatment with CPAP improves cerebral vascular reactivity. This is a prospective study with OSAS patients. The apnea test (ApT) was calculated as an increase of mean artery velocity during apnea: [Artery velocity in apnea minus Resting artery velocity]/Resting artery velocity expressed as percentage. After 2 years of CPAP treatment, the test was repeated. Seventy-six patients represented the study pool. After 2 years of treatment with CPAP, we were able to conduct a reassessment in 65 patients. Of the 65 patients who finished the clinical study, 56 were men, and 9 were women, with an average age of 48.1 +/- 10.4 years. There was an improvement in the ApT after CPAP treatment (30.8 +/- 12.1 vs 39.8 +/- 15.1; p:0.000). The values of cerebral blood flow velocities, diastolic blood pressure in apnea, and basal heart rate decreased. Cerebral vascular reactivity in OSAS patients measured by ApT improved after 2 years of CPAP.