THE CHANGES IN CEREBRAL AND MUSCULAR HEMODYNAMICS INDUCED BY SLEEP APNEA/HYPOPNEA EVENTS SHOW DISTINCT PATTERNS UNDER CPAP TITRATION

Abstract

PURPOSE: Obstructive sleep apnea (OSA) can induce hemodynamic changes in the brain and peripheral tissues. OSA is effectively treated with continuous positive airway pressure (CPAP). But the cerebral hemodynamics under CPAP pressures is still unknown. We aim to characterize the changes in cerebral and muscular hemodynamics induced by sleep apnea/hypopnea events under CPAP pressures. METHODS: 33 patients with sleep apnea did CPAP titration. A standard all-night Video-Polysomnography measurement was recorded from each patient. Frequency-domain multi-distance near-infrared spectroscopy (FDMD-NIRS) measurements were conducted to measure the changes of blood volume (BV), tissue oxygen saturation (StO2), oxygenated (HbO2) and deoxygenated hemoglobin (HHb) in the left forehead and the left bicep brachii muscle. RESULTS: In apnea/hypopnea shorter than 15-second we found no significant changes in cerebral hemodynamics but significant desaturation in the muscle after the event onsets, and cerebral BV/HbO2/StO2 increased in the later phase and post-events (Fig(a)). In events longer than 15-second cerebral BV/HbO2/StO2 first quickly decreased and then increased (Fig(b-c)). The increasing cerebral perfusion was followed by a later increment in HHb. The cerebral StO2 decreased post-events. In the muscle BV/ HbO2/StO2 immediately increased in the events and then decreased. Muscular HHb increased in the whole events. CONCLUSIONS: Cerebral and muscular hemodynamics change differently and the patterns of changes depend on the durations of the apnea/hypopnea events. CLINICAL IMPLICATIONS: The interactions between CPAP and pathophysiologies of sleep apnea (e.g., intrathoracic pressure, vasomotor and autonomic activities, cerebral autoregulation) are complicated. The duration of apnea/hypopnea may be an important factor needs to be considered in CPAP therapy.