This research study is designed to learn, first, whether two anesthetics have different effects on collapse seen within the upper airway during sleep endoscopy. A second purpose is to learn whether collapse at several levels of the upper airway is associated with obstructive sleep apnea that persists after adenotonsillectomy, the surgery that removes the tonsils and adenoids.

Inclusion Criteria:

1. Diagnosed with Obstructive sleep apnea (OSA) by the following criteria: Obstructive Apnea Index (OAI) ≥ 1 or Apnea Hypopnea Index (AHI) ≥ 1.5, confirmed on nocturnal, laboratory-based polysomnography within the previous 12 months scored using American Academy of Sleep Medicine pediatric criteria in an accredited sleep lab.

2. Considered to be a surgical candidate for adenotonsillectomy to treat OSA by an board-certified or board-eligible otolaryngologist.

3. Clinical determination by the child's otolaryngologist surgeon that the child would benefit from sleep endoscopy prior to adenotonsillectomy due to one or more reported risk factors for residual sleep apnea after surgery, which may include:

   1. Obese (>95th percentile of body mass index for age)
   2. Severe preoperative OSA (AHI ≥10 events/hour)
   3. Discordance between awake physical exam (eg. small tonsils) and sleep apnea symptoms or severity;
   4. African American race
   5. Age ≥7 years old

4. Male or Female ages 3.00 - 11.99 years of age at the time of consent

5. Parent/guardian ability to understand and willingness to sign a written informed consent..

6. Parent/guardian must understand/read/speak English or Spanish and be able and willing to complete questionnaires.

Exclusion Criteria:

1. Previous adenotonsillectomy or other upper airway surgery (including tracheostomy) with the exception of isolated adenoidectomy if it occurred >18 months prior to recruitment.
2. Major medical diagnosis that may be exacerbated by the study treatment, pose undue risk to the patient, or that may impact interpretation of study results
3. History of allergic reaction to or contraindication to receiving propofol, dexmedetomidine, ketamine or sevoflurane
4. Allergy to eggs, egg products, soybeans or soybean products.
5. Contraindication to receiving general anesthesia

A coordinator and anesthesiologist will be unblinded.