Obstructive Sleep Apnea Phenotyping to Understand Pathophysiology and Improve Treatment and Outcomes

Obstructive sleep apnea (OSA) is an increasingly common disorder associated with major adverse consequences. Recent advances in OSA pathophysiology using detailed upper airway physiology techniques have identified four key pathophysiological traits or “endotypes” that contribute to OSA. These include impaired upper airway anatomy, poor upper airway muscle function during sleep, unstable control of breathing (high loop gain) and a low threshold for awakening to minor reductions in airflow (low respiratory arousal threshold). In addition, clinical OSA phenotypes based on standard diagnostic and clinical criteria have recently been defined to help categorize patients according to a single or a combination of distinct disease features. The overarching goal of these “phenotyping” approaches is to facilitate tailored therapy based on specific causes or features of the disease to reduce the associated adverse consequences in those who are most at risk of harm. This chapter summarizes the latest advances in the research findings aimed at achieving these important objectives.