Transverse maxillary deficiency is one of the main etiological factors for obstructive sleep apnea. In adults, increased nasal airflow resistance due to decreased nasal cavity volume can be treated with maxillary expansion using the Surgically Assisted Rapid Maxillary Expansion (SARME) technique. A decrease in the negative pressure in the airways, which is responsible for the collapse of the pharyngeal and nasal walls, and enlargement of the internal nasal valve (INV), which is the region most resistant to airflow intake, alleviates nasal obstruction symptoms following SARME. Deep palatal vault, crossbite, and oral breathing are the main diagnostic findings of transverse maxillary deficiency. Practitioners should be aware of the potential cardiopulmonary diseases in patients with obstructive sleep apnea before SARME. The bony resistance regions in the piriform aperture, zygomatic buttress, pterygoid junction, and fused midpalatal suture should be carefully released during the surgical procedure. Bone-borne devices can be chosen for the activation period to reduce relapse and dehiscence in the molar–premolar region because of the minimized unintended tooth movements.