J Rhinol.  2011 May;18(1):53-58.

Comparison of Upper Airway Morphology between Position-Dependent Sleep Apnea Patients and Position-Independent Sleep Apnea Patients

  • 1Department of Otorhinolaryngology-Head & Neck Surgery, School of Medicine, Kyungpook National University, Daegu, Korea. sookim@knu.ac.kr


The aim of this study is to compare polysomnography (PSG) data and upper airway morphology between a position-dependent sleep apnea (PDSA) group and a position-independent sleep apnea (PISA) group.
This is a retrospective analysis into which 58 patients who were evaluated with overnight polysomnography, lateral cephalometry, and multidetector computed tomography (MD-CT, spiral CT scan) to diagnosis obstructive sleep apnea were enrolled. The patients were divided in two groups: the PDSA group who had a supine apnea-hypopnea index (AHI) that was at least two times higher than the non-supine AHI and the PISA group in whom the AHI in the supine position was less than twice that in the lateral position. Twelve cephalometric variables were measured. MD-CT measurements were evaluated in four neck levels from the hard palate to the top of the epiglottis. Minimal cross-sectional area (mCSA) and collapsibility index (CI) were calculated at each level.
AHI was significantly higher in the PISA compared with PDSA. None of the cephalomeric measurements were significantly different between the two groups. In the MD-CT measurements, the mCSA of the low retropalate area (LRP) in the awake state was significantly lower in the PISA group compared to that in the PDSA group. In the sleep state, the CI was significantly higher in the high and low retroglossal areas (HRG and LRG) in the PISA compared to those in the PDSA group.
In the supine position, PISA had increased collapsibility at the levels of the HRG and LRG during sleep compared to those in PDSA. In the future, a further evaluation with MD-CT in a non-supine position is needed.


Sleep apnea; Polysomnography; Spiral CT scan
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