The effect of continuous positive airway pressure on total cerebral blood flow in 23 healthy awake volunteers

Continuous positive airway pressure (CPAP) is the gold standard treatment for obstructive sleep apnea (OSAS). However, the influence of CPAP on cerebral blood flow (CBF) is not well understood. Ultrasound can be used to estimate CBF, but there is no widespread accepted protocol. This study investigates the influence of CPAP on total CBF in 23 healthy awake subjects by measuring flow velocity (FV) and lumen diameter of the left and right proximal Internal Carotid Arteries (ICA), Vertebral Arteries (VA), and Middle Cerebral Arteries (MCA) using Duplex Color Doppler Ultrasound (US) with and without CPAP at a level of 15 cm H 2 O. Transcutaneous Carbon Dioxide (PtcCO2) level, heart rate, Blood Pressure (BP), and oxygen saturation (SaO 2 ) were monitored before and after each test. The measurements indicate that CPAP results in a decrease of CBF by 12.5% (p-value