[Significance of oscillatory impedance in etiological determination of arousal in sleep related respiratory disorders].

Conventional registration of cardiorespiratory data may not explain daytime sleepiness in some patients. Polysomnography may detect arousal reactions that can only be explained by additional registration of esophageal pressure. We developed a device (oscillatory impedance [OI]) which applies an oscillating flow via a nasal mask that allows to detect the pathophysiologic findings of upper airway resistance syndrome. 25 patients (age 47.3 +/- 5.6 years, body mass index 26.6 +/- 3.8 kg/m2) underwent conventional polysomnography and additional measurement of OI. In 59% arousal reactions could not be explained by respiratory data whereas OI demonstrated intermittend obstruction of extrathoracic airways. We therefore conclude that patients with daytime sleepiness that cannot be explained by conventional polysomnographic registrations should undergo measurement of OI.