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Why don't all heavy snorers have obstructive sleep apnea?
1Gui de Chauliac Medical Center, ENT Department, St. Charles Hospital, Montpellier, France.
The American Review of Respiratory Disease
|June 1, 1991
Summary
Obstructive sleep apnea (OSA) patients experience airway collapse due to a narrow velopharynx and large hypopharynx. This study differentiates their airway morphology from heavy snorers without apnea.
Area of Science:
- Respiratory Medicine
- Sleep Medicine
- Anatomy
Background:
- Patients with obstructive sleep apnea (OSA) and heavy snorers exhibit similar intrathoracic suction pressures during sleep.
- Airway occlusion occurs only in OSA patients, suggesting morphological differences.
- Upper airway morphology may influence airflow dynamics and airway collapse during sleep.
Purpose of the Study:
- To investigate differences in upper airway morphology between patients with OSA, nonapneic heavy snorers, and control subjects.
- To determine if airway dimensions correlate with the propensity for airway collapse during sleep.
Main Methods:
- Pharyngeal computed tomography (CT) was used to measure upper airway cross-sectional areas in awake subjects.
- Nocturnal breathing was monitored using a static charge-sensitive bed (SCSB).
- Airway dimensions were analyzed at the velopharyngeal (VP), tongue base (TB), and hyoid bone (HB) levels.
Main Results:
- OSA patients had a narrower velopharyngeal airspace compared to controls.
- Nonapneic snorers had narrower airways at the tongue base and hyoid bone levels compared to controls.
- The velopharyngeal/hyoid bone (VP/HB) ratio was significantly lower in OSA patients, distinguishing them from nonapneic snorers.
Conclusions:
- Airway collapse in OSA may be linked to a narrow velopharynx combined with a large hypopharynx.
- Heavy snorers without apnea might avoid collapse due to airway damping in the hypopharynx.
- Upper airway morphology plays a critical role in the pathophysiology of obstructive sleep apnea.