The Application of CT to Localize the Upper Airway Obstruction Plane in Patients with OSAHS

OBJECTIVE: To identify a correlation in terms of airway obstruction between awake and sleep apnea using spiral computed tomography (CT). STUDY DESIGN: Case series with planned data collection. SETTING: College medical center. METHODS: Sixty-one patients diagnosed with obstructive sleep apnea/hypopnea syndrome (OSAHS) underwent CT scans under 3 conditions: quiet breathing while awake, the end of deep inspiration during wakefulness, and apnea while asleep. The upper airway morphology under the 3 conditions was compared, and the accuracy of the obstructive planes as determined by CT scans under the 2 awake conditions was analyzed while considering the obstructive planes that occurred during apnea as a reference. RESULTS: The differences in the anteroposterior diameter, lateral dimension, and cross-sectional area of the retropalatal and retroglossal regions among the 3 states were statistically significant. Obstruction of the retropalatal region occurred in 100%, whereas retroglossal obstruction occurred in 44.3% of the 61 cases during sleep apnea. The coincidence rate between the awake quiet breathing and the sleep apnea was 85.2% in the retropalatal obstruction and 52.5% in the retroglossal obstruction. The coincidence rate between the awake deep inspiration and the sleep apnea was 82.0% in the retropalatal obstruction and 54.1% in the retroglossal obstruction. CONCLUSION: The main obstructive plane in patients with OSAHS was the retropalatal region. An awake upper airway CT scan can properly diagnose palatopharyngeal obstruction; however, it is not suitable for detecting retroglossal obstruction.