Selective Continuous Positive Airway Pressure Withdrawal With Supplemental Oxygen During Slow-Wave Sleep as a Method of Dissociating Sleep Fragmentation and Intermittent Hypoxemia-Related Sleep Disruption in Obstructive Sleep Apnea

Obstructive sleep apnea (OSA) is considered to impair memory processing and increase the expression of amyloid-β (Aβ) and risk for Alzheimer’s disease (AD). Given the evidence that slow-wave sleep (SWS) is important in both memory and Aβ metabolism, a better understanding of the mechanisms by which OSA impacts memory and risk for AD can stem from evaluating the role of disruption of SWS specifically and, when such disruption occurs through OSA, from evaluating the individual contributions of sleep fragmentation (SF) and intermittent hypoxemia (IH). In this study, we used continuous positive airway pressure (CPAP) withdrawal to recapitulate SWS-specific OSA during polysomnography (PSG), creating conditions of both SF and IH in SWS only. During separate PSGs, we created the conditions of SWS fragmentation but used oxygen to attenuate IH. We studied 24 patients (average age of 55 years, 29% female) with moderate-to-severe OSA [Apnea-Hypopnea Index (AHI); AHI4% > 20/h], who were treated and adherent to CPAP. Participants spent three separate nights in the laboratory under three conditions as follows: (1) consolidated sleep with CPAP held at therapeutic pressure (CPAP); (2) CPAP withdrawn exclusively in SWS (OSASWS) breathing room air; and (3) CPAP withdrawn exclusively in SWS with the addition of oxygen during pressure withdrawal (OSASWS + O2). Multiple measures of SF (e.g., arousal index) and IH (e.g., hypoxic burden), during SWS, were compared according to condition. Arousal index in SWS during CPAP withdrawal was significantly greater compared to CPAP but not significantly different with and without oxygen (CPAP = 1.1/h, OSASWS + O2 = 10.7/h, OSASWS = 10.6/h). However, hypoxic burden during SWS was significantly reduced with oxygen compared to without oxygen [OSASWS + O2 = 23 (%min)/h, OSASWS = 37 (%min)/h]. No significant OSA was observed in non-rapid eye movement (REM) stage 1 (NREM 1), non-REM stage 2 (NREM 2), or REM sleep (e.g., non-SWS) in any condition. The SWS-specific CPAP withdrawal induces OSA with SF and IH. The addition of oxygen during CPAP withdrawal results in SF with significantly less severe hypoxemia during the induced respiratory events in SWS. This model of SWS-specific CPAP withdrawal disrupts SWS with a physiologically relevant stimulus and facilitates the differentiation of SF and IH in OSA.

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Baseline Lighter Sleep and Lower Saturation Are Associated With Improved Sleepiness and Adherence on Continuous Rather Than Autotitrating Positive Airway Pressure

Clinical EEG and Neuroscience ◽

10.1177/1550059419892759 ◽

2019 ◽

Vol 51 (3) ◽

pp. 174-179 ◽

Cited By ~ 2

Author(s):

R. Bart Sangal ◽

Nimish Sudan

Keyword(s):

Obstructive Sleep Apnea ◽

Sleep Apnea ◽

Side Effects ◽

Continuous Positive Airway Pressure ◽

Airway Pressure ◽

Positive Airway Pressure ◽

Arousal Index ◽

Cpap Titration ◽

Obstructive Sleep ◽

Lower Saturation

The objective was to test whether there were better outcomes on switching from autotitrating positive airway pressure (APAP) to continuous positive airway pressure (CPAP) in a clinic sample of patients with obstructive sleep apnea (OSA). Patients prescribed APAP in 2015-2016 and belonging to a subset characterized by side effects, or suboptimal response or adherence, were advised a switch to CPAP following a CPAP titration polysomnography. The main analysis was for improvement (after switch from APAP to CPAP) in (1) sleepiness, wakefulness inability, and fatigue, using change from baseline in the Sleepiness–Wakefulness Inability and Fatigue Test (delta SWIFT), and Epworth Sleepiness Scale (delta ESS), and (2) adherence using percentage of days with ≥4-hour use and whether there was ≥4-hour use on ≥70% days. To determine possible predictors for switching, additional analysis was performed for differences at baseline between patients switching and those staying on APAP. A total of 148 patients were switched from APAP to CPAP and had greater improvement in delta SWIFT (5.2 vs 4.1, P = .004), greater improvement in delta ESS (3.6 vs 2.9, P = .011), and better adherence (79.4% vs 74.3%, P = .006) on CPAP than on APAP. More patients were adherent on CPAP than on APAP (83.1% vs 68.9%, P = .006). Patients switching had higher baseline arousal index and stage N1 sleep, and lower nadir oxygen saturation, than 96 patients not switching. Thus, there is a subset of patients with better outcomes after switching to CPAP than on APAP. Patients with baseline lighter sleep (indicated by more arousals and stage N1), or greater desaturation, may be more likely to do better on CPAP than on APAP. CPAP may be the preferable treatment in a significant subset of patients. If APAP is used first anyway, side effects, or suboptimal response or adherence, should lead to consideration of switching to CPAP based on a CPAP titration polysomnography.

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