Site of upper airway obstruction in patients with idiopathic obstructive sleep apnea.

We developed a technique to determine the site of upper airway obstruction in patients with idiopathic obstructive sleep apnea (OSA). This technique is based on the analysis of inspiratory airflow pressures at various levels of the pharyngeal airway during sleep. Pharyngeal pressure was measured by a moveable Millar catheter pressure transducer. The catheter's position in the airway was localized radiographically. Ten patients with OSA were tested: five patients were found to have upper airway obstruction at the level of the soft palate, and five had upper airway obstruction at the base of the tongue. We concluded that measuring airway pressures at multiple sites along the airway is useful in localizing the site of obstruction in patients with OSA, and may have important implications in terms of the patient's response to surgical treatment.