Characterizing Upper Airway Collapse to Guide Patient Selection for Oral Appliance Therapy for Obstructive Sleep Apnea

Characterizing Upper Airway Collapse to Guide Patient Selection for Oral Appliance Therapy for Obstructive Sleep Apnea

Characterizing Site and Severity of Upper Airway Collapse to Guide Patient Selection for Oral Appliance Therapy for Obstructive Sleep Apnea

Obstructive Sleep Apnea (OSA) is characterized by collapse of one or more pharyngeal structures during sleep (velum, tongue base, lateral walls, epiglottis). Structure-specific therapies for OSA have emerged as alternatives to positive airway pressure (PAP). Oral appliance (OA) therapy is increasingly being indicated for OSA treatment, although a complete response occurs in approximately 50% of patients. In general, OA devices are designed to maintain the mandible and/or tongue in a protruded posture during sleep, preventing upper airway obstruction. Limited studies in awake or sedated patients have demonstrated the effects of mandibular advancement on aspects of pharyngeal structure and function. The objective of the proposed research is to fully characterize upper airway collapse in OSA patients during natural sleep and use this information to understand why some patients appear to exhibit a large improvement in pharyngeal collapsibility whereas others do not.

OSA patients will undergo a baseline sleep endoscopy study to identify the site of pharyngeal collapse. Subsequently, they will undergo two clinical polysomnographies (PSGs) to measure the effect of an oral appliance (a site specific therapy) on upper airway collapsibility and sleep apnea severity. During the first hour of each clinical PSG, the passive pharyngeal collapsibility will be determined using the standard 5-breath continuous positive airway pressure (CPAP) drop method. During the remainder of the night, patients will be monitored to determine sleep apnea severity (apnea-hypopnea index). These measurements will allow the investigators to determine which pharyngeal collapsing site responds best (both in terms of collapsibility and AHI) to mandibular advancement with an oral appliance. Patients who have their own oral appliance will be recruited. In addition, patients without an oral appliance will be provided with a temporary oral appliance for the study.

Patients without a prescribed oral appliance will have a device provided for the duration of the study (BluePro, BlueSom; used for investigational purposes only). The device provided is a prefabricated thermoplastic customizable mandibular advancement splint.

The passive pressure-flow relationship is characterized by the critical closing pressure (Pcrit) , and the ventilatory flow at atmospheric pressure ( V passive). Pcrit and V passive will be determined using the standard 5-breath CPAP drop method. The change in collapsibility will be compared across subgroups defined by the site of collapse measured using sleep-endoscopy. Patients will sleep supine for this measurement.

The change in apnea-hypopnea index (AHI, 3% desaturation or arousal criteria; OA therapy minus control) will be compared across subgroups defined by the site of collapse measured using sleep-endoscopy. Baseline collapsibility will be incorporated as a predictor of the change in AHI.

During the portion of the night dedicated to measuring sleep apnea severity, peak flow will also be measured during sleep to quantify activated upper airway collapsibility.

Proportion of sleep in Non rapid eyes movement ( NREM) stage 1,one of the standard measures of sleep quality, will be assessed.

Inclusion Criteria: Patients with Obstructive Sleep Apnea Exclusion Criteria: Any unstable cardiac condition (other than well controlled hypertension) or pulmonary problems. Any medication known to influence breathing, sleep/arousal or muscle physiology Concurrent sleep disorders (insomnia, narcolepsy, central sleep apnea or parasomnia) Claustrophobia Inability to sleep supine Periodontal disease and/or insufficient number of teeth Allergy to lidocaine or oxymetazoline hydrochloride For women: Pregnancy