Institute for Continuing Education

Upper Airway Resistance Syndrome

Course Objectives

Upon successful completion of this module, you will be able to:

• Analyze the pathophysiology of Upper Airway Resistance Syndrome (UARS), including mechanisms of increased upper airway resistance, respiratory effort-related arousals (RERAs), sleep fragmentation, and the continuum from normal breathing to obstructive sleep apnea.
• Evaluate the historical evolution and current nosological status of UARS within sleep medicine, including its initial description, controversial classification debates, and integration into current diagnostic frameworks (ICSD-3 and AASM scoring manuals).
• Apply specialized polysomnographic techniques for UARS detection, including esophageal pressure monitoring (gold standard), nasal pressure transducer flow limitation identification, pulse transit time measurement, and respiratory effort-related arousal (RERA) scoring according to AASM criteria.
• Synthesize the clinical features distinguishing UARS from obstructive sleep apnea and primary snoring, including patient demographics, symptom profiles (excessive daytime sleepiness, fatigue, insomnia), physical examination findings, and respiratory disturbance index patterns.
• Compare and contrast diagnostic approaches to UARS, including the necessity and limitations of esophageal pressure monitoring, alternative surrogate measures of respiratory effort, home sleep apnea testing applicability, and the role of clinical judgment in diagnosis.
• Assess treatment options for UARS, including positive airway pressure therapy (CPAP, APAP, bilevel PAP), oral appliances, positional therapy, surgical interventions, weight management, and patient selection for various therapeutic modalities.
• Explain the physiological consequences and clinical significance of respiratory effort-related arousals, including autonomic activation, sleep architecture disruption, neurocognitive effects, cardiovascular implications, and quality of life impact in patients with increased upper airway resistance.

Course Information

Upper airway resistance syndrome (UARS) was first recognized in children in 1982.[1] The term UARS, however, was not used until adult cases were reported in 1993.[2] The description of UARS brought clinicians’ attention to a group of patients left undiagnosed and untreated despite severe impairment. Since the original description, the syndrome has been recognized in patients with clinical and polysomnography presentations different from that of obstructive sleep apnea syndrome (OSAS). However, controversies exist regarding the syndrome. Some have rejected it as a distinct clinical entity or even doubted its existence;[3] others have considered it part of a spectrum that includes benign snoring, UARS, obstructive hypopnea syndrome, OSAS, and hypoventilation. The term sleep-disordered breathing (SDB) is used widely today, often without clear definition by the authors. Supposedly it includes all these breathing abnormalities in sleep, including central apnea and hypoventilation. Clinically, the disease entity of SDB is often called sleep-related breathing disorders. In clinical practice, a label of SDB or sleep-related breathing disorders is applied when a breathing abnormality is found in sleep but no clear distinction between UARS and obstructive apnea-hypopnea syndrome (OSAHS) is attempted or can be made. In the past few years, there have been at least two review articles published on UARS in general[4] and in children.[5] This review is aimed at coverage of recent progress progresses in recognition and understanding of UARS, with greater emphasis on data published over the period of the past 2 years.

Since the first description of a polygraphic pattern called obstructive sleep apnea in the Pickwickian syndrome in 1965,[6,7] sleep medicine has undergone an evolution. UARS was born as part of the efforts to describe a generally unrecognized patient population that is nonobese with clinical features not matching those reported with OSAHS. Unfortunately, many sleep breathing abnormalities are still ignored because of the belief that SDB is synonymous with OSAHS and that patients must be obese. Such limited views have already led to the underdiagnosis and undertreatment of OSAS in women (the forgotten sex).[8] With use of new techniques, such as the esophageal catheter for esophageal pressure measurement (Pes)[9] and nasal cannula/pressure transducer,[10] it has become more convenient to identify subtle changes in breathing patterns during sleep. Recently, UARS has been linked to many somatic, psychiatric, or psychosomatic conditions, including parasomnias, attention deficit disorder or attention deficit hyperactivity disorder, fibromyalgia, and chronic insomnia. Also, to many clinicians, the distinction between UARS and OSAS lies in the clinical severity, such as apnea-hypopnea index (AHI) and level of oxygen desaturation, but research in recent years supports the presence of a different pathophysiology in the two syndromes.