The upper airway resistance syndrome

The upper airway resistance syndrome (UARS) is a recently described form of sleep-disordered breathing in which repetitive increases in resistance to airflow within the upper airway lead to brief arousals and daytime somnolen ce, This review will first describe the chronological progression of our un derstanding of UARS within the broader context of sleep-disordered breathin g, The primary symptom, daytime somnolence, appears to result directly from repetitive EEG arousals. The level of negative intrathoracic pressure is t he most likely stimulus for arousal, possibly mediated by mechanoreceptors in the upper airway. A general consensus regarding the exact clinical defin itions and the physiologic measurement techniques leading to a diagnosis do es not exist, although esophageal manometry and pneumotachographic airflow measurements taken during polysomnography are the "gold standard." Less inv asive diagnostic modalities have been proposed, but none of them have been well-validated, Aside from daytime somnolence, hypertension is an important sequela of this disorder, likely resulting from autonomic and cardiovascul ar changes induced by increased negative intrathoracic pressure, Nasal cont inuous positive airway pressure is the most efficacious form of therapy, al though low patient compliance may limit its practical application. The safe ty and efficacy of surgical treatments are poorly documented in the literat ure, Palatal tissue reduction by radiofrequency ablation and the use of ora l appliances hold promise as safe and effective modalities, but these treat ments require further study.