Mechanisms of Pharyngeal Collapse in Sleep Apnea, Study B

Study Overview
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Brief Summary
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In obstructive sleep apnea (OSA), the upper airway recurrently closes during sleep. The mechanisms that lead to airway closure are not completely understood. Some studies have shown that there is progressive narrowing of the pharyngeal airway across breaths during expiration (Progressive Expiratory Narrowing, PEN) preceding an obstructive apnea. The cause of PEN is unknown. The investigators will test if lung volumes and low respiratory drive play a role in PEN.

Detailed Description
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The mechanisms that lead to airway closure in OSA are not completely understood. Some studies have shown that there is progressive narrowing of the pharyngeal airway across breaths during expiration (Progressive Expiratory Narrowing, PEN) preceding an obstructive apnea. The investigators will test if lung volumes and low respiratory drive play a role in PEN. To this end, the investigators will visualize the pharynx of sleep apnea patients during sleep using a thin endoscope during sleep while simultaneously measuring lung volumes, genioglossus electromyogram, and pharyngeal pressure during flow-limited breaths. Flow limitation will be induced by sustained reductions of continuous positive airway pressure (CPAP).

Official Title
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Mechanisms of Pharyngeal Collapse in Sleep Apnea, Study B

Conditions
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Sleep Apnea

Intervention / Treatment
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* Other: Induction of flow limitation


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Normal subjects or patients with OSA Exclusion Criteria: Any unstable cardiac condition (other than well controlled hypertension) or pulmonary problems. Any medication known to influence breathing, sleep/arousal or muscle physiology Concurrent sleep disorders (insomnia, narcolepsy, central sleep apnea or parasomnia) Claustrophobia Inability to sleep supine Allergy to lidocaine or oxymetazoline hydroclhoride For women: Pregnancy

Ages Eligible for Study
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Minimum Age: 21 Years
Maximum Age: 65 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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Accepts Healthy Volunteers

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Other
Intervention Model: Single Group Assignment
Masking: None (Open Label)


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Induction of flow limitation<br>Flow limitation will be induced by sustained reductions in continuous positive airway pressure during sleep | Other: Induction of flow limitation<br> <br> |

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Difference in peak inspiratory flow | Measured peak inspiratory flow will be compared to predicted peak inspiratory flow during flow restricted breaths. The time frame for the outcome will be the duration of induced flow limitation (3 minutes each) . Flow limitation will be induced several times during the night. Flow limited breaths will be averaged. | 3 minutes | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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Sleep Apnea, Pathophysiology