Dataset Information

Mechanisms used to restore ventilation after partial upper airway collapse during sleep in humans.

ABSTRACT:

Background

Most patients with obstructive sleep apnoea (OSA) can restore airflow after an obstructive respiratory event without arousal at least some of the time. The mechanisms that enable this ventilatory recovery are unclear but probably include increased upper airway dilator muscle activity and/or changes in respiratory timing. The aims of this study were to compare the ability to recover ventilation and the mechanisms of compensation following a sudden reduction of continuous positive airway pressure (CPAP) in subjects with and without OSA.

Methods

Ten obese patients with OSA (mean (SD) apnoea-hypopnoea index 62.6 (12.4) events/h) and 15 healthy non-obese non-snorers were instrumented with intramuscular genioglossus electrodes and a mask/pneumotachograph which was connected to a modified CPAP device that could deliver either continuous positive or negative pressure. During stable non-rapid eye movement sleep the CPAP was repeatedly reduced 2-10 cm H2O below the level required to eliminate flow limitation and was held at this level for 5 min or until arousal from sleep occurred.

Results

During reduced CPAP the increases in genioglossus activity (311.5 (49.4)% of baseline in subjects with OSA and 315.4 (76.2)% of baseline in non-snorers, p = 0.9) and duty cycle (123.8 (3.9)% of baseline in subjects with OSA and 118.2 (2.8)% of baseline in non-snorers, p = 0.4) were similar in both groups, yet patients with OSA could restore ventilation without cortical arousal less often than non-snorers (54.1% vs 65.7% of pressure drops, p = 0.04). When ventilatory recovery did not occur, genioglossus muscle and respiratory timing changes still occurred but these did not yield adequate pharyngeal patency/ventilation.

Conclusions

Compensatory mechanisms (increased genioglossus muscle activity and/or duty cycle) often restore ventilation during sleep but may be less effective in obese patients with OSA than in non-snorers.

SUBMITTER: Jordan AS

PROVIDER: S-EPMC2094262 | biostudies-literature | 2007 Oct

REPOSITORIES: biostudies-literature

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Publications

Mechanisms used to restore ventilation after partial upper airway collapse during sleep in humans.

Jordan Amy S AS Wellman Andrew A Heinzer Raphael C RC Lo Yu-Lun YL Schory Karen K Dover Louise L Gautam Shiva S Malhotra Atul A White David P DP

Thorax 20070405 10

<h4>Background</h4>Most patients with obstructive sleep apnoea (OSA) can restore airflow after an obstructive respiratory event without arousal at least some of the time. The mechanisms that enable this ventilatory recovery are unclear but probably include increased upper airway dilator muscle activity and/or changes in respiratory timing. The aims of this study were to compare the ability to recover ventilation and the mechanisms of compensation following a sudden reduction of continuous positi ...[more]

PMID: 17412778

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Project description:Importance:Adenotonsillar hypertrophy is an important cause of obstructive sleep apnea (OSA) in children. However, residual OSA and abnormal polysomnographic findings have been reported in up to 75% of cases after adenotonsillectomy. Other anatomical and functional factors that influence upper airway structures, including the lateral pharyngeal wall, have rarely been studied in children with OSA. Objective:To determine whether the upper airway structures can be evaluated using head and neck ultrasonography and if there is an association between the ultrasonographic measurements for these structures and severity of OSA seen on polysomnography in children. Design, Setting, and Participants:Prospective, single-center, observational study of 82 children younger than 18 years with a diagnosis of sleep-disordered breathing (20 with primary snoring, 62 with OSA, as determined by the apnea-hypopnea index) and admitted to a tertiary teaching hospital for adenotonsillectomy. Exposures:Ultrasonography and polysomnography. Main Outcomes and Measures:Ultrasonographic measurements of upper airway structures. Results:Of the 82 children studied, 62 (76%) were boys; mean (SD) age, 7.7 (6.2). There was no significant difference found in tonsillar dimensions or volume between the children with OSA and those with primary snoring. However, the mean (SD) total lateral pharyngeal wall and the total neck thicknesses at the retropalatal level were both greater in children with OSA than in those with primary snoring at rest (24.9 [4.4] mm vs 21.3 [2.6] mm; difference, 3.61 mm; 95% CI of difference, 1.48-5.74 mm for lateral pharyngeal wall; and 59.9 [14.4] mm vs 49.9 [11.2] mm; difference, 10.9 mm, 95% CI of difference, 3.8-17.9 mm for the total neck). Conclusions and Relevance:Estimated tonsillar volume measured using ultrasonography had no relationship with the apnea-hypopnea index in childhood sleep-disordered breathing. However, the lateral pharyngeal wall was significantly thicker in children with OSA than in those with primary snoring at rest.

Dataset Information

Mechanisms used to restore ventilation after partial upper airway collapse during sleep in humans.

Background

Methods

Results

Conclusions

Publications

Mechanisms used to restore ventilation after partial upper airway collapse during sleep in humans.

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