Respiratory Arousal From Sleep: Mechanisms and Significance

Abstract

The mechanisms by which respiratory stimuli induce arousal from sleep and the clinical significance of these arousals have been explored by numerous studies in the last two decades. Evidence to date suggests that the arousal stimulus in nonrapid eye movement sleep (NREM) is related to the level of inspiratory effort rather than the individual stimuli that contribute to ventilatory drive. A component of the arousal stimulus proportional to the level of inspiratory effort may originate in mechanoreceptors either in the upper airway or respiratory pump. Medullary centers responsible for ventilatory drive may also send a signal proportionate to the level of drive to higher centers in the brain which are responsible for arousal. Thus, the arousal stimulus may consist of multiple components, each increasing as inspiratory effort increases. The level of effort triggering arousal is an index of the arousability of the brain (arousal threshold). A deeper stage of sleep, central nervous system depressants, prior sleep fragmentation, and the presence of obstructive sleep apnea (OSA) have been observed to increase the arousal threshold to airway occlusion. Less information is available concerning the mechanisms of arousal from rapid eye movement (REM) sleep. While REM sleep is associated with the longest obstructive apneas in patients with OSA, normal human subjects appear to have a similar or lower arousal threshold to respiratory stimuli in REM compared to NREM sleep. Recent studies have challenged the assumption that the termination of all obstructive apnea is dependent on arousal from sleep. Improvements in methods to detect and quantitate changes in the cortical electroencephalogram (EEG) may better define the relationship between arousal and apnea termination. This may result in improved criteria for identifying EEG changes of clinical significance. While little is known concerning the mechanisms of arousal in central sleep apnea, arousal may play an important role in inducing this type of apnea in some patients.

Genetic Associations with Obstructive Sleep Apnea Traits in Hispanic/Latino Americans

“…As a surrogate for respiratory arousability, we analyzed average apnea and hypopnea event duration length, with shorter duration events indicating greater arousability (49). This phenotype was only moderately correlated with AHI (r = 0.220).…”

Unilateral Ablation of Pre-Bötzinger Complex Disrupts Breathing during Sleep but Not Wakefulness

“…SDB is a significant health problem in adults (6), greatly impacting quality of life (7,8). CSA, characterized by an absence of respiratory effort, is less common in young adults but becomes increasingly prevalent with age (11,12), even in elderly individuals who are relatively ''healthy'' (16). The etiology of CSA is presently unknown; however, we show here and have shown previously (5) that disruption of preBö tC function may be an underlying or contributing cause.…”

Sleep Disorders Associated with Chronic Kidney Disease

“…Treatment resulted in a significant reduction of nocturnal periodic limb movements and improvement on the MWT. SAS, RLS and PLMD are prevalent in patients with advanced kidney disease and could explain EDS, but some studies suggested that other factors related to renal disease or its treatment may contribute to EDS (52,53).…”