This study focuses on a sleep disorder called **Obstructive Sleep Apnea (OSA)**, which causes people to choke during sleep. **Drug Induced Sleep Endoscopy (DISE)** is a procedure used to see how the throat behaves while a person is sedated, similar to sleeping. The study explores how **lung volume** affects the throat during DISE. Participants will be from sleep surgery clinics and will have a DISE as part of their usual evaluation for OSA surgery. During DISE, they will be in one of two groups: one group will use a "turtle shell" ventilator to change lung volume, and the other will use electrodes on the neck to stimulate the **phrenic nerve** (a nerve that helps the diaphragm, a muscle that aids breathing) to change lung volume. Both groups will have a lung function test. This study aims to help predict if surgery for OSA will work and may lead to new treatments.

• Study involves one DISE procedure as part of routine surgical evaluation.
• Participants are assigned to one of two groups for lung volume manipulation.
• No major risks have been identified in similar, past studies.