Variable site of oropharyngeal narrowing and regional variations of oropharyngeal collapsibility among snoring patients during wakefulness and sleep

Abstract

The oropharynx shows rhythmic caliber changes in accordance with the respiratory cycle. Dynamic imaging of the oropharynx is required to evaluate airway changes associated with snoring and obstructive sleep apnea. The purpose of this study was to determine the sites of narrowing/obstruction and to measure the regional collapsibility of the oropharynx during respiration during the sleep and awake cycles in snoring patients. Seven snoring patients were included for this study. Electron Beam Tomograms of the oropharynx were taken while the patient was awake and asleep, and dynamic views were reconstructed. The site of narrowing or obstruction varied widely among patients and differed from awake to asleep. The mean of smallest minimum cross-sectional area of the oropharynx was 60.38+/-42.97 mm2 in the awake state and 16.90+/-20.43 mm2 in the asleep state. Although the collapsibility of the oropharynx showed considerable regional variations, it increased during sleep at the overall oropharynx. The low retropalatal region showed the smallest minimum cross-sectional area and the highest collapsibility; however, the most prominent changes in the minimum cross-sectional area and collapsibility during sleep were observed in the high retroglossal region.