Obstructive sleep apnea (OSA) is a common disorder characterized by recurrent choking episodes during sleep. OSA affects over 25 million Americans and is associated with increased risks of hypertension, diabetes, cardiovascular disease, and stroke. The severity of OSA is measured by the number of complete or partial obstructive events per hour of sleep, and quantified for diagnostic and research purposes as the apnea-hypopnea index (AHI). Continuous positive airway pressure (CPAP) is the first line therapy for treating OSA, however, 20-40% of patients do not tolerate wearing a pressurized mask during sleep. Several surgeries can treat OSA, including pharyngeal soft tissue surgery, skeletal advancement surgery, and hypoglossal nerve stimulation which are deemed successful when surgery reduces the AHI to below 5 events per hour. Successful surgical treatment of OSA is highly variable with rates of success as low as 40% in early studies that looked at pharyngeal soft tissue surgery. Selecting OSA patients for surgery based on certain pathophysiologic characteristics has vastly improved surgical success rates, up to 60-80% depending on the surgery. However, the application of OSA pathophysiological assessment for surgical selection remains incomplete. This study will explore a wider range of pathophysiological factors to improve surgical outcomes and anticipate that further understanding of these relationships will support development of new surgical and non-surgical treatments for those who may not benefit from current treatment options.~Drug induced sleep endoscopy (DISE) is currently used to help determine appropriate patients for OSA surgery. During DISE, a fiber optic camera is placed through the nose into the throat to visualize airway collapse patterns during sedation mimicking natural sleep. The standardized method of describing airway collapse is known as the Velum, Oropharynx, Tongue Base, Epiglottis (VOTE) score which assesses the severity and pattern of collapse at four different anatomic sites of the upper airway. Previous studies have shown that airway collapse patterns visualized on DISE affect surgical outcomes.~One overlooked pathophysiologic factor in the evaluation for OSA surgery is lung volume. Studies of lung physiology in OSA patients have found that lower functional residual capacity (FRC) and expiratory reserve volume (ERV) on pulmonary function testing, a commonly used procedure in pulmonary medicine, is associated with increased OSA severity. Experimental studies in OSA patients have shown that when negative pressure was used to expand the chest (e.g., iron lung) during sleep, the subsequent increased lung volume resulted in decreased upper airway collapsibility and reduced OSA severity. Despite this evidence, lung volume is not utilized as part of the evaluation for OSA surgery. The goal of this study is to determine if lung volume is useful in predicting surgical success and whether improving lung volumes can be used as an adjunctive therapy with surgery to treat OSA.~Immediately following DISE performed as part of their routine surgical workup for treatment of OSA, participants will have a repeat a DISE with a non-invasive negative pressure ventilator. Participants will also complete pulmonary function testing.
Obstructive sleep apnea (OSA) is a disorder where a person has recurrent choking episodes during sleep. Surgery can treat OSA and drug induced sleep endoscopy (DISE) is a procedure that surgeons use to evaluate the throat while a person is sedated, mimicking sleep, to help determine if surgery might be effective. Lung volume can influence OSA severity but the relationship between lung function and throat collapse seen on DISE has not been well studied. This study aims to see if lung volume influences what is happening in the throat during DISE. Participants will be recruited from the sleep surgery clinic where they are being evaluated for surgery to treat their OSA. Participants will have a lung function test performed. They will then have a DISE that is performed as part of their routine surgical workup for treatment of OSA. Additionally, a negative pressure turtle shell ventilator will be placed over the participants chest during DISE to manipulate lung volumes to see if it can improve throat collapse. The findings of this study will be important in improving pre-surgical evaluation of patients to better predict if surgery can help as well as potentially develop new surgical therapies for the treatment of OSA.