DISE: Phenotyping Obstruction Patterns

Obstructive sleep apnea (OSA) is characterized by recurrent upper airway obstruction due to inadequate muscle tone during sleep leading to nocturnal hypercapnia, repeated oxyhemoglobin desaturations and arousals. Continuous positive airway pressure (CPAP) is the therapeutic mainstay for OSA, but adherence remains poor. Currently, there exist 3 classes of surgical therapy for OSA, each addressing a specific pathologic structure: skeletal surgery (target: jaw bones), neurostimulation (target: tongue), and soft tissue (target: soft palate). Unfortunately, there is a critical knowledge gap in terms of accurately identifying a patient's underlying mechanism of obstruction; as a result, the efficacy of surgical treatment is limited. Drug-induced sleep endoscopy (DISE) represents an opportunity to evaluate the upper airway in sleep-like conditions. In its current clinical form, however, DISE does not routinely determine the functional impact of anatomic and neuromuscular factors on airflow obstruction. In June 2020, the investigators implemented a pilot protocol (IRB # 833511) to utilize measures of airflow, pressure catheters, and ultrasound to enhance DISE exams. Over the course of 100 patients, they refined the research protocol to generate a safe, efficient, and comprehensive physiologic exam of the upper airway in the clinical setting (Dedhia et al, ORL, 2021, in press). Upper airway pressure-flow relationships will be characterized during a standard-of-care DISE by stepping through a range of nasal pressure (CPAP) levels to derive functional determinants of upper airway obstruction during sleep. The investigators' preliminary work in this area has shown patients requiring lower pressures to restore airflow experience improved outcomes with neurostimulation surgery. Their overall hypothesis is that upper airway pressure-flow relationships can be used to predict response to all 3 major classes of sleep surgery: skeletal, neurostimulation, and soft tissue. They will address this hypothesis by characterizing upper airway pressure-flow relationships while utilizing objective anatomic measurements from CT and ultrasound. These findings will allow investigators to streamline the upper airway exam during DISE, and will further the goal of developing personalized solutions that address specific pathogenic mechanisms of pharyngeal collapse and airflow obstruction during sleep.