The impact of central and obstructive respiratory events on cerebral oxygenation in adults with sleep disordered breathing

Obstructive sleep apnea(OSA)and central sleep apnea(CSA)are two main types of sleep disordered breathing(SDB).While the changes in cerebral hemodynamics triggered by OSA events have been well studied using near-infrared spectroscopy(NIRS),they are essentially unknown in CSA in adults.Therefore,in this study,we compared the changes in cerebral oxygenation between OSA and CSA events in adult patients using NIRS.Cerebral tissue oxygen saturation(StO_(2))in 13 severe SDB patients who had both CSA and OSA events was measured using frequency-domain NIRS.The changes in cerebral StO_(2)desaturation and blood volume(BV)in the¯rst hour of natural sleep were compared between different types of respiratory events(i.e.,277 sleep hypopneas,161 OSAs and 113 CSAs)with linear mixed-effect models controlling for confounders.All respiratory events occurred during non-rapid eye movement(NREM)sleep.We found that apnea events induced greater cerebral desaturations and BV°uctuations compared to hypopneas,but there was no difference between OSA and CSA.These results suggest that cerebral autoregulation in our patients are still capable to counteract the pathomechanisms of apneas,in particularly the negative intrathoracic pressure(ITP)caused by OSA events.Otherwise larger BV°uctuations in OSA compared to CSA should be observed due to the negative ITP that reduces cardiac stroke volume and leads to lower systematic blood supply.Our study suggests that OSA and CSA may have similar impact on cerebral oxygenation during NREM sleep in adult patients with SDB.

Near-infrared spectroscopy(NIRS)as a useful tool to evaluate the treatment efficacy of positive airways pressure therapy in patients with obstructive sleep apnea syndrome(OSAS):A pilot study

In obstructive sleep apnea syndrome(OSA)the periodic reduction or cessation of breathing dueto narrowing or occlusion of the upper airway during slep leads to an impaired cerebral vascularautoregulation that is associated with an increased cardiovascular risk,including stroke.Con-tinuous positive airways pressure(CPAP)therapy at night is the most effective treatment forOSA and has been shown to reduce the cardiovascular risk in OSA patients.However,there is nosuitable bedside monitoring method evaluating the recovery of cerebral hemodynamics duringCPAP therapy.Near-infrared spectroscopy(NiRS)is idelly suited for non-invasive monitoringthe cerebral hemodynamics during sleep due to its properties of local measurement,totally sa feapplication and good tolerance to motion.In this pilot study,we monitored cerebral hemody-namics during standard CPAP therapy at night in thre patients with severe OSA using NIRS.We found periodic oscllations in HbO2,HHb,tisue oxygenation index(TO1)and blood volume(BV)associa ted with periodic apnea events without CPAP in all OSA patients.These osillationswere eliminated under the optimal CPAP pressures in all patients.These results sugg ested thatthe recovery of cerebral hemodynamics impaired by apnea events can be evaluated by bedsideNIRS measurements in real time during ll night CPAP therapy.NIRS is a usefi bedsidemonitoring tool to evaluate the treatment elicacy of CPAP therapy in patients with OSA.