Abstract WP437: Sleep Apnea and Cerebral Blood Flow: the Role of Autoregulation

Objective: Obstructive sleep apnea (OSA) is a stroke risk factor and is increasingly recognized as a risk factor for cognitive impairment. Altered cerebral autoregulation may play a role in these relationships. We measured the association between OSA and two forms of cerebral autoregulation: (1) dynamic cerebral autoregulation (DCA), which plays a homeostatic role; and (2) vasomotor reactivity (VMR), which is a measure of cerebrovascular reserve. We hypothesized that both VMR and DCA would be impaired in subjects with OSA. Methods: We recruited subjects with untreated OSA. VMR and DCA were measured with continuous transcranial Doppler (TCD) of the middle cerebral arteries (MCA). DCA was measured with phase shift analysis where lower degrees of phase shift indicate greater impairment; values <24 degrees are abnormal. VMR was measured as % change in MCA velocity in response to 5% CO2 inhalation; values <2% change are abnormal. We assessed the relationship between apnea-hypopnea index (AHI) and autoregulatio...