The goal of this clinic trial is to evaluate the impact of dexmedetomidine as an adjunct pain pain medication on opioid-free recovery in children undergoing adenotonsillectomy with Suprazygomatic maxillary nerve block (SZMB). The main questions it aims to answer are:

• Does SZMB with the local anesthetic ropivacaine and the adjuvant dexmedetomidine result in less pain
• Is dexmedetomidine associated with an improved quality of recovery at home Researchers will compare pain in participants given an SZMB with ropivacaine and an adjuvant dexmedetomidine, participants given SZMB with ropivacaine only, and a SZMB with ropivacaine and dexmedetomidine given intravenously.

Participants will:

• Be given the SZMB during the surgery.
• Be evaluated after surgery to measure their opioid consumption, pain severity, level of agitation, and level of delirium
• Complete a daily questionnaire for 7 days after surgery on the patients pain and recovery

Inclusion Criteria:

• Scheduled for elective partial adenotonsillectomy,
• STUBR score ≥ 3, indicating significant sleep-disordered breathing
• Patients whose parents are fluent in French of English will be enrolled

Exclusion Criteria:

• Scheduled to undergo total extracapsular adenotonsillectomy or adenoidectomy-only procedures
• Patient requires prolonged intubation postoperatively
• the anesthesiologist does not adhere to the standardized anesthesia protocol
• Patients with neurological or cardiac congenital deficits, with cardiac arrhythmias (non-sinus rhythm), implanted pacemakers, on chronic therapy with drugs that have known effects on sympathetic and parasympathetic activity (antimuscarinics, beta-2 adrenergic agonists, alpha-1 adrenergic antagonists or antiarrhythmic agents, tricyclic antidepressants)
• ASA physical status III or higher
• Parent/legal guardians refuses to participate
• Patients scheduled for surgery without an appointment at the Montreal Children's Hospital (MCH) Preoperative Clinic will not be enrolled in the study.