This study aims to assess the use of intranasal dexmedetomidine (IN-dex) as a sole agent in aiding the successful completion of a MRI scans in children. Dexmedetomidine, a routinely used anesthetic agent in our institution, has many benefits including sedation with neuro-protective and respiratory sparing features. We will test its effectiveness in completing MRI scans in children that would otherwise be given a full general anesthetic.

Purpose:

To assess the use of IN-dex as a sole agent in aiding the successful completion of a MRI scan in children.

Hypothesis:

We hypothesize that the optimal dose for IN-dex to produce appropriate sedation for MRI will be between 1 and 3 mcg/kg. We also hypothesize that this dose will be lower in the older age group.

Justification:

The dose required for IN-dex to enable safe sedation for MRI scanning as a sole agent is undetermined at present. This study will enable us to find the optimal dose for effective sedation for MRI scanning in a range of age groups. This will avoid the need for propofol and remifentanil general anesthesia (that is the current standard of care) in this group of patients. Our motivation for avoiding general anesthesia is that there is ongoing concern that general anesthesia causes long term neurocognitive effects in children. Finally, identifying a safe yet effective dose of IN-dex, which can be nurse-administered, will also allow us to improve access to MRI scans that are limited by the access to general anesthesia.

Objectives:

1. To determine the dose of IN-dex that, when used as a sole agent, produces minimal to moderate sedation that is adequate for successful completion of MRI in children with >90% effectiveness.
2. To explore the logistics of a nurse-administered sedation protocol to increase access to the MRI.

Research Design:

We propose a dose finding study of IN-dex using the biased coin design (BCD) method in three different age groups (3 to <8 years, 8 to <12 years, 12 to <19 years). The study specific interventions will include identification of children appropriate for the study following detailed assessment using a scoring system developed by our Child Life specialists for use at their MRI preparation session.

Statistical Analysis:

The dose of IN-Dex that produces mild to moderate sedation in 90% of subjects will be calculated using the pooled adjacent violators algorithm (PAVA) and bootstrap methods will be used to calculate the 95% confidence limits.

Inclusion Criteria:

• ASA 1 or 2
• Scheduled for elective MRI scan on the general anesthesia list
• Child Life MRI simulation score of 6-10 (Figure 1)
• Age 3 - 18

Exclusion Criteria:

• Taking existing opioid, sedative, or cannabinoid medication
• Severe learning disability defined as the inability to follow simple commands
• Severe Cardiac disease
• Chronic hypertension
• Allergy to dexmedetomidine
• Nasal anatomical abnormality
• Known or anticipated difficult airway