Dynamic upper airway changes during sleep in patients with obstructive sleep apnea syndrome

The narrowing pattern of the upper airway in obstructive sleep apnea patients may be different in sleep as compared with awake. Three different types of obstruction were observed in these subjects during drug-induced sleep. The different obstruction pattern during drug-induced sleep suggests that different strategies should be selected in upper airway management.

To identify the sites of narrowing and evaluate dynamic upper airway movement in patients with obstructive sleep apnea syndrome (OSAS) while awake and asleep.

This study included 10 patients treated for OSAS between August 2003 and June 2004. Overnight polysomnography was performed on all patients. Parameters including gender, age, neck circumference, and body mass index were recorded. Ultra-fast MRI during awake and drug-induced sleep was arranged to evaluate the dynamic motion of the upper airway.

The narrowing pattern of the upper airway during awake differed from the narrowing pattern during drug-induced sleep in 3 of 10 subjects. Three different types, palatal obstruction, combined upper and lower pharyngeal obstruction, and circumferential obstruction of the upper airway, were observed in these patients during drug-induced sleep.