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State-related changes in upper airway caliber and surrounding soft-tissue structures in normal subjects
F J Trudo1, W B Gefter, K C Welch
1Departments of Medicine and Radiology, and Center for Sleep and Respiratory Neurobiology, University of Pennsylvania Medical Center, Philadelphia, Pennsylvania, USA.
American Journal of Respiratory and Critical Care Medicine
|October 14, 1998
Summary
Upper airway narrowing during sleep is linked to changes in soft tissues. The retropalatal airway volume decreases significantly, primarily due to lateral pharyngeal wall thickening and soft palate displacement.
Area of Science:
- Sleep Medicine
- Respiratory Physiology
- Medical Imaging
Background:
- Upper airway caliber changes with state, impacting breathing.
- Soft tissue structures like the lateral pharyngeal walls, tongue, and soft palate influence airway dimensions.
Purpose of the Study:
- To investigate state-dependent changes in upper airway caliber using MRI.
- To identify the specific soft tissue contributions to airway narrowing during sleep.
Main Methods:
- 15 healthy subjects underwent MRI during wakefulness and sleep after deprivation.
- Magnetic Resonance Imaging (MRI) was used to measure airway volumes and dimensions.
- Analysis focused on retropalatal (RP) and retroglossal (RG) airway regions.
Main Results:
- Retropalatal airway volume decreased by 19% during sleep (p=0.03).
- Minimal cross-sectional airway area significantly reduced in RP (228%, p=0.004) and RG (22%, p=0.02) regions during sleep.
- Narrowing in the RP region was associated with increased lateral pharyngeal wall thickness (7%, p=0.04) and posterior soft palate displacement.
Conclusions:
- Lateral pharyngeal wall thickening and soft palate displacement are key factors in upper airway narrowing during sleep.
- The retropalatal region is more susceptible to collapse than the retroglossal region.
- These findings highlight the role of soft tissue dynamics in maintaining airway patency during sleep.