OSA with Upper Airway Resistance Syndrome
Upper airway resistance syndrome (UARS) is a variant of OSA that is characterized by a partial collapse of the airway resulting in increased resistance to airflow. The increased respiratory effort required results in multiple sleep fragmentations as measured by very short alpha EEG arousals. Snoring may not be a feature of UARS. The resistance to airflow is typically subtle and does not result in apneic or hypopneic events. However, it does result in increasingly negative intrathoracic pressure during inspiration, which can be measured using an esophageal manometer as an adjunct to a polysomnogram. Therefore, this diagnosis rests on polysomnographic documentation of >10 EEG arousals per hour of sleep correlated with episodes of reduced intrathoracic pressures.