Dexmedetomidine and Propofol for Pediatric MRI Sedation

The purpose of this study is to compare the results of combining two anesthetic medications (dexmedetomidine and propofol) in low doses with a standard dose of a single drug that is commonly used to provide sedation/anesthesia for MRI studies in young children (propofol). The drugs used for the MRI scan in this study will be chosen randomly. Half the patients will receive small doses of propofol and dexmedetomidine. The other half will receive propofol administered constantly throughout the scan. Other drugs that may be used include sevoflurane and nitrous oxide at the start of the sedation (for placing an intravenous), lidocaine (to reduce the pain of propofol injection) and glycopyrrolate (to prevent the heart rate from decreasing too low. The investigators will record 5 additional blood pressures and heart rates. If additional medications are required to complete the scan, the investigators will administer whatever is necessary. At the end of the study, the investigators will have an observer record the time it takes for participants to spontaneously open eyes , to be able to drink liquids and/or eat and to behave as before the study. Also, it is very important that the investigators find out from participants about changes in behavior, or if eating or sleeping habits were unusual following completion of the study. For that reason, the investigators will call participants in a day or so following the MRI scan. The investigators expect to recruit 40 children between the ages of 12 and 72 months for the study and hope to have the study completed in December 2018.