The investigators propose to determine the propofol and remifentanil sparing effects of a single dose of dexmedetomidine in the dental population. The investigators plan to do this by performing a blinded study with 4 test groups (3 experimental and 1 control), using BIS monitoring to titrate TIVA infusion to an acceptable depth of anesthesia.

Purpose:

To determine an optimal dose of dexmedetomidine for its anesthetic sparing effect, without extending post-operative stay.

Hypothesis:

The investigators hypothesize that dexmedetomidine will cause a clinically significant reduction of 30% in the amount of propofol and remifentanil required to maintain adequate depth of anesthesia, as monitored through the Bispectral Index.

Justification:

The dose-sparing effect of dexmedetomidine on TIVA requirements and the dose-response relationship between dexmedetomidine and TIVA dosing regimens has not been explored in young children. This study will have many relevant applications to many areas of pediatric anesthesia practice, such as craniofacial and neurosurgery, sedation techniques in diagnostic and interventional radiology, out of OR sedation, and in all young children in whom minimizing anesthesia exposure is increasingly sought given possible concerns over the long term neurocognitive effects of surgery and anesthesia in early life.

Objectives:

To investigate the dose-sparing effect on a propofol/remifentanil infusion of bolus doses of dexmedetomidine and to characterize the dose-response relationship between dexmedetomidine doses and TIVA dose reduction.

Research Design:

The investigators propose a randomized, 4-group comparative study to characterize the effects of different bolus doses of dexmedetomidine on the infusion requirements of propofol and remifentanil. The study-specific interventions will include a bolus of dexmedetomidine (or placebo) at induction of anesthesia, and maintenance of anesthesia, titrated to a Bispectral index of 50-60, with propofol and remifentanil infusions.

Statistical Analysis:

Standard statistical analysis will be undertaken using R Foundation for Statistical Computing, Vienna, Austria). Summary data will be tabulated and presented as median (IQR). Mean infusion rates of propofol and remifentanil will be compared between groups using Wilcoxon signed-rank test, with 95% confidence intervals obtained by the Hodges-Lehmann estimator. Dose (in mcg/kg) of additional opioids given in PACU will be tabulated and compared using Fisher's exact test. Bonferroni corrections will be applied as appropriate whenever multiple comparisons are performed.

Inclusion Criteria:

• ASA 1-2
• Elective dental surgery
• Planned general anesthesia with TIVA
• Age 2-10 years

Exclusion Criteria:

• General anesthesia with inhalation induction
• Documented seizure disorder
• Cardiac disease
• Cardiac rhythm abnormalities
• Chronic hypertension
• Weight < 5th centile or > 95th centile for age
• Pre-operative administration of anxiolytics (such as benzodiazepines or opioid analgesics)
• Hypersensitivity to dexmedetomidine or any other study medication

Assessor of sedation scores post-procedure will be blinded to group allocation.