The dynamics of cerebral vascular reserve in sleep apnea patients during continuous positive airway pressure therapy

Abstract

Objective. To explore the possibility of cerebral hemodynamic reserve (CHR) normalization in patients with obstructive sleep apnea syndrome (OSAS), aged over fifty, who received continuous positive airway pressure (CPAP) therapy. Material and methods. The main group (20 patients, aged 50—65 years, with severe OSAS) and the control group (20 volunteers without snoring and OSAS matched for age and physical status) were studied. Diagnosis included cardio-respiratory monitoring of nocturnal sleep and ultrasound examination of cerebral blood flow with functional tests (breath holding and hyperventilation) and calculating the coefficient of vasomotor reactivity (CVMR) before the start of CPAP-therapy and after one month therapy. Results. The significant CVMR decrease in vertebral (VA) and basilar arteries (BA) in patients with OSAS compared to the control group was identified: 38.9±8.5 and 55.7±11.3 for VA, 36.8±15.7 and 54.0±5.4 for BA. After one month CPAP-therapy, no significant coefficient gains was observed: 38.9±8.5 and 42.3±9.1 for VA, 36.8±15.7 and 37.2±7.7 for BA. Conclusion. The reduction of CVMR in patients older than 50 years with severe OSAS suggests the disturbance of CHR. The absence of its recovery within one month of CPAP therapy may be indicative of the irreversible damage of the cerebral blood flow regulation mechanisms. Continued observations for a longer period are needed.