Upper airway resistance syndrome

Obstruction of the upper airway may cause arousals resulting in daytime sleepiness and cardiovascular disturbances. The upper airway resistance syndrome may easily be overlooked because conventional measurements of oronasal airflow and thoracic and abdominal efforts are not sensitive enough. By measuring esophageal pressure even small disturbances can be detected, but the esophageal gauge may disturb sleep. We conclude that other, less invasive methods like measurements of impedance by forced oscillation technique, or flattening of the inspiratory flow contour could be valid alternatives in the diagnosis of the upper airway resistance syndrome. Other methods, such as measurements of the pulse transit time, phase angle, or systolic blood pressure profile are promising, but need further evaluation.