Does Pre and Postoperative Dextromethorphan Reduce Post-tonsillectomy Pain in Children?

With Institutional ethics board and Health Canada approval and parental consent and child assent, pediatric patients (ages 3-12) undergoing tonsillectomy or adenotonsillectomy (under standardized anesthesia) will be randomized to receive dextromethorphan hydrobromide (1mg/kg orally) 30 min preoperatively and again 8 hours postoperatively OR placebo (syrup identical in taste, appearance and volume) at the same time points. The primary outcome is an integrated assessment of perioperative pain scores and opioid use for 24 hours postoperatively. Pain scores were collected preoperatively at rest and then at 1,2,3,8,9,10 and 24 hours postoperatively using the validated Children's Hospital of Eastern Ontario Pain Scale (CHEOPS). Secondary outcomes include nausea, vomiting, respiratory depression, and bleeding recorded by blinded observers for 24 hours postoperatively.

Our hypothesis is that dextromethorphan will decrease the incidence/severity of post-tonsillectomy pain. The improved pain control will be apparent through reduced opioid consumption and integrated pain scores. This will result in a reduced incidence of opioid-related side effects and adverse events.

Inclusion criteria

• American Society of Anesthesiologist's (ASA) physical classification I and II
• tonsillectomy or adenotonsillectomy
• admission to extended postoperative care unit

Exclusion criteria

• use of monoamine oxidase inhibitors, serotonin reuptake inhibitors or tricyclic antidepressants
• requirement of preoperative sedation
• recent dextromethorphan use (<24 h before surgery)
• intolerance, sensitivity or contraindication to any agents used in the study
• pre-existing chronic pain or chronic analgesic use
• body mass index (BMI) for age percentile greater than 90
• confounding procedural factors which might affect the validity of the data
• inability to adhere to study protocol
• contraindication to volatile anesthetics