Effects of Lung Volume on Upper Airway Patency During Drug Induced Sleep Endoscopy

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 DISE that is performed as part of their routine surgical workup for treatment of OSA. Additionally, during the DISE, they will participate in one of two study groups. One group will have a negative pressure "turtle shell" ventilator placed over the participants chest during DISE to manipulate lung volumes to see if it can improve throat collapse. A second group will have phrenic nerve stimulation to contract the diaphragm to improve lung volumes to see if it can improve throat collapse. Both groups will also have a lung function test performed. 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.

Inclusion Criteria: * Adult patients (≥ 18 yrs) willing and capable of providing informed consent * Obstructive sleep apnea (AHI ≥ 5 events/hour) * Must be willing and able to provide informed consent to participate in the study. * Interested in surgical treatments of OSA and have consented for a DISE procedure as part of their routine clinical evaluation. * Patients are evaluated and cleared by anesthesia prior to the procedure. Exclusion Criteria: * No significant uncontrolled medical co-morbidities (e.g., uncontrolled hypertension, unstable angina, uncompensated heart failure or COPD). * Any medical comorbidity that would prevent the patient from receiving anesthesia or having surgery * Inability to tolerate negative pressure ventilator or perform PFT (i.e. claustrophobia) * No incapacitating disability that interferes with execution of the protocol