PROJECT SUMMARY/ABSTRACT Obstructive sleep apnea (OSA) affects 1-4% of children, can lead to cognitive, behavioral, and cardiovascular morbidity, and is associated with a 226% increase in healthcare utilization. Guidelines recommend adenotonsillectomy (AT) as first-line treatment for pediatric OSA and nearly half a million are performed in U.S. children annually. However, AT is a one-size-fits-all procedure for a condition with pathophysiology that can differ dramatically between individuals based on differences in upper airway anatomy and dynamics. These differences likely account for the high rate of persistent post-AT OSA. Drug-induced sleep endoscopy (DISE) is a flexible fiber-optic assessment of the upper airway performed under sedation that has potential to direct individualized surgical treatment and improve outcomes in children with OSA. While early series have demonstrated good outcomes after DISE-assisted surgery, there is currently no well-controlled, prospective data to support the use of DISE in children. Prospective research on pediatric DISE has been fundamentally hindered by the lack of a standardized sedation protocol for the procedure. Choice of sedative may be important as anesthetic drugs impact upper airway patency to various degrees. Fundamental questions about how DISE findings should be interpreted and applied cannot be answered without first understanding which anesthetic facilitates the most useful assessment of upper airway obstruction. The goal of this project is to determine which anesthetic should be used for DISE. We will perform a randomized controlled trial comparing the two anesthetic drugs most commonly used to sedate children for the procedure: dexmedetomidine (DEX) and propofol. The central hypothesis of this proposal is that PROP exaggerates dynamic obstruction compared to DEX, and thus DISE under DEX provides a more useful and predictive measurement of upper airway obstruction during sleep. To test this, we will 1) compare mean DISE obstruction scores under sedation with PROP versus DEX and 2) test the predictive value of obstruction seen on DISE but left untreated by AT on post-AT outcomes (improvement in symptoms, behavior, quality-of-life, and polysomnography measures) and need for further treatment for persistent post-AT OSA. To accomplish these aims, Dr. Kirkham will receive mentorship, focused didactic coursework and training in pediatric sleep medicine and on the design and implementation of randomized controlled trials. Dr. Kirkham’s long-term goal is to become a leading independent clinical investigator and expert in the surgical treatment of pediatric OSA. An NHLBI K23 award will provide Dr. Kirkham with the protected time and needed training to achieve her career goals and improve outcomes for children with sleep apnea.