Dataset Information

Arousal-Induced Hypocapnia Does Not Reduce Genioglossus Activity in Obstructive Sleep Apnea.

ABSTRACT:

Study objectives

To determine whether arousals that terminate obstructive events in obstructive sleep apnea (OSA) (1) induce hypocapnia and (2) subsequently reduce genioglossus muscle activity following the return to sleep.

Methods

Thirty-one untreated patients with OSA slept instrumented with sleep staging electrodes, nasal mask and pneumotachograph, end-tidal CO2 monitoring, and intramuscular genioglossus electrodes. End-tidal CO2 was monitored, and respiratory arousals were assigned an end-arousal CO2 change value (PETCO2 on the last arousal breath minus each individual's wakefulness PETCO2). This change value, in conjunction with the normal sleep related increase in PETCO2, was used to determine whether arousals induced hypocapnia and whether the end-arousal CO2 change was associated with genioglossus muscle activity on the breaths following the return to sleep.

Results

Twenty-four participants provided 1137 usable arousals. Mean ± SD end-arousal CO2 change was -0.2 ± 2.4 mm Hg (below wakefulness) indicating hypocapnia typically developed during arousal. Following the return to sleep, genioglossus muscle activity did not fall below prearousal levels and was elevated for the first two breaths. End-arousal CO2 change and genioglossus muscle activity were negatively associated such that a 1 mm Hg decrease in end-arousal CO2 was associated with an ~2% increase in peak and tonic genioglossus muscle activity on the breaths following the return to sleep.

Conclusions

Arousal-induced hypocapnia did not result in reduced dilator muscle activity following return to sleep, and thus hypocapnia may not contribute to further obstructions via this mechanism. Elevated dilator muscle activity postarousal is likely driven by non-CO2-related stimuli.

SUBMITTER: Cori JM

PROVIDER: S-EPMC6251523 | biostudies-literature | 2017 Jun

REPOSITORIES: biostudies-literature

ACCESS DATA

Publications

Arousal-Induced Hypocapnia Does Not Reduce Genioglossus Activity in Obstructive Sleep Apnea.

Cori Jennifer M JM Thornton Therese T O'Donoghue Fergal J FJ Rochford Peter D PD White David P DP Trinder John J Jordan Amy S AS

Sleep 20170601 6

<h4>Study objectives</h4>To determine whether arousals that terminate obstructive events in obstructive sleep apnea (OSA) (1) induce hypocapnia and (2) subsequently reduce genioglossus muscle activity following the return to sleep.<h4>Methods</h4>Thirty-one untreated patients with OSA slept instrumented with sleep staging electrodes, nasal mask and pneumotachograph, end-tidal CO2 monitoring, and intramuscular genioglossus electrodes. End-tidal CO2 was monitored, and respiratory arousals were ass ...[more]

PMID: 28419356

Similar Datasets

Project description:Obstructive sleep apnea syndrome (OSA) and restless legs syndrome (RLS) with periodic limb movement during sleep (PLMS) are two sleep disorders characterized by repetitive respiratory or movement events associated with cortical arousals. We compared the cerebral hemodynamic changes linked to periodic apneas/hypopneas with arousals (AHA) in four OSA-patients with periodic limb movements (PLMA) with arousals in four patients with RLS-PLMS using near-infrared spectroscopy (NIRS). AHA induced homogenous pattern of periodic fluctuations in oxygenated (HbO2) and deoxygenated (HHb) hemoglobin, i.e., the decrease of HbO2 was accompanied by an increase of HHb during the respiratory event and resolved to reverse pattern when cortical arousal started. Blood volume (BV) showed the same pattern as HHb but with relative smaller amplitude in most of the AHA events.These changing patterns were significant as Wilcoxon signed-rank tests gave p < 0.001 when comparing the area under the curve of these hemodynamic parameters to zero. By contrast, in PLMA limb movements induced periodic increments in HbO2 and BV (Wilcoxon signed-rank tests, p < 0.001), but HHb changed more heterogeneously even during the events coming from the same patient. Heart rate (HR) also showed different patterns between AHA and PLMA. It significantly decreased during the respiratory event (Wilcoxon signed-rank test, p < 0.001) and then increased after the occurrence of cortical arousal (Wilcoxon signed-rank test, p < 0.001); while in PLMA HR first increased preceding the occurrence of cortical arousal (Wilcoxon signed-rank test, p < 0.001) and then decreased. The results of this preliminary study show that both AHA and PLMA induce changes in cerebral hemodynamics. The occurrence of cortical arousal is accompanied by increased HR in both events, but by different BV changes (i.e., decreased/increased BV in AHA/PLMA, respectively). HR changes may partially account for the increased cerebral hemodynamics during PLMA; whereas in AHA probable vasodilatation mediated by hypoxia/hypercapnia is more crucial for the post-arousal hemodynamics. The differences between changes of cerebral hemodynamics and HR may indicate different pathological mechanisms behind these two sleep disorder events.

Project description:RationaleA total of 20-30% of respiratory events in obstructive sleep apnea are terminated without clear arousal. Arousals are thought to predispose to further events by promoting hyperventilation, hypocapnia, and upper-airway dilator muscle hypotonia. Therefore, events terminated without arousal may promote stable breathing.ObjectivesTo compare physiologic changes at respiratory event termination with American Sleep Disorders Association (ASDA) Arousal to No Arousal, and determine whether secondary respiratory events are less common and have higher dilator muscle activity after No Arousal compared with ASDA Arousal.MethodsPatients with obstructive sleep apnea wore sleep staging, genioglossus (EMG(GG)), and tensor palatini (EMG(TP)) electrodes plus a nasal mask and pneumotachograph. During stable sleep, continuous positive airway pressure (CPAP) was lowered for 3-minute periods to induce respiratory events. Physiologic variables were compared between events terminated with (1) ASDA Arousal, (2) No Arousal, or (3) sudden CPAP increase (CPAPinc, control).Measurements and main resultsSixteen subjects had adequate data. EMG(GG), EMG(TP), and heart rate increased after ASDA Arousal (340 ± 57%, 215 ± 28%, and 110.7 ± 2.3%) and No Arousal (185 ± 32%, 167 ± 15%, and 108.5 ± 1.6%) but not CPAPinc (90 ± 10%, 94 ± 11%, and 102.1 ± 1%). Ventilation increased more after ASDA Arousal than No Arousal and CPAPinc, but not after accounting for the severity of respiratory event. Fewer No Arousals were followed by secondary events than ASDA Arousals. However, low dilator muscle activity did not occur after ASDA Arousal or No Arousal (EMG(GG) rose from 75 ± 5 to 125 ± 7%) and secondary events were less severe than initial events (ventilation rose 4 ± 0.4 to 5.5 ± 0.51 L/min).ConclusionsRespiratory events that were terminated with ASDA Arousal were more severely flow-limited, had enhanced hyperventilation after event termination, and were more often followed by secondary events than No arousal. However, secondary events were not associated with low dilator muscle activity and airflow was improved after both No Arousal and ASDA Arousal.

Dataset Information

Arousal-Induced Hypocapnia Does Not Reduce Genioglossus Activity in Obstructive Sleep Apnea.

Study objectives

Methods

Results

Conclusions

Publications

Arousal-Induced Hypocapnia Does Not Reduce Genioglossus Activity in Obstructive Sleep Apnea.

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