Computerized tomography in obstructive sleep apnea. Correlation of airway size with physiology during sleep and wakefulness

Pathophysiologic changes during sleep in patients with obstructive apnea are often associated with alterations in upper airway function during awake periods. To determine whether these functional changes are related to abnormal airway structure, we performed computerized tomography (CT) in 20 awake patients with obstructive apnea and in 10 control subjects. The CT scan measurements of cross-sectional areas of the nasopharynx, oropharynx, and hypopharynx in apneic patients were significantly reduced (p<0.05) compared with those in the control subjects. Sites of obstruction varied, and apparent airway occlusion occurred in 6 patients. Reduced pharyngeal size correlated with increased sleep-disordered breathing rates (p<0.05), more severe nocturnal oxygen desaturation (p<0.05), and the presence of a saw-tooth pattern of flow-volume curves obtained during awake periods (p<0.05). Structural upper airway narrowing is detectable with CT in awake patients with obstructive sleep apnea.