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).~Recent studies and the FDA have raised concerns that anesthesia for longer than three hours may have effects on behavior and learning. Although investigators do not know if these effects are caused by drugs or the medical condition a child is being treated for, in December 2016, the FDA published the information below regarding anesthesia for children:~General anesthetic and sedation drugs are used to put people into a deep sleep so they do not feel pain during surgery or procedures.~These drugs are usually injected into a vein or breathed in through a mask. General anesthetic and sedation drugs are widely used to ensure the health, safety, and comfort of children and adults undergoing surgery or other procedures.~Recent studies in children suggest that a single, relatively short exposure to general anesthetic and sedation drugs in infants or toddlers is unlikely to have negative effects on behavior or learning. More research is still needed to fully understand how anesthetics might affect brain development, especially longer or repeated exposures and in more vulnerable children. Anesthetic and sedation drugs are necessary for infants, children, and pregnant women who require surgery or other painful and stressful procedures. https://www.fda.gov/Drugs/DrugSafety/ucm532356.htm Research in neonatal and infant animals has demonstrated that sedative and anesthetic agents, like propofol, produce adverse effects on brain development, including loss of brain cells resulting in long-term, possibly permanent changes in learning and behavior. These adverse effects appear to occur mostly after prolonged periods of sedation or anesthesia (generally greater than 3 hours) and when brain development is occurring at a rapid rate (which roughly occurs in children under 3 years of age). It is not known if similar adverse effects occur in humans. Study participants should be advised that the drugs used to accomplish the procedure may have the potential to increase the loss of nerve cells in the developing brain of young child and that the clinical significance of any such changes is not known. There are some animal studies that suggests dexmedetomidine may be better for a growing infant's brain. However, the effects of dexmedetomidine alone or in combination with propofol on the developing brain have not been thoroughly tested to date. 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. Investigators will record 5 additional blood pressures and heart rates. If additional medications are required to complete the scan, investigators will administer whatever is necessary. At the end of the study, an observer will record the time it takes for spontaneous eye opening, to be able to drink liquids and/or eat and to behave as before the study. Also, it is very important that investigators learn in the following day or two how the participant behaved at home; whether eating, behavior and sleeping were unusual. For that reason, the investigator will call the participant a day or so following the MRI scan.~The investigators expect to recruit 70 children between the ages of 12 and 72 months for the study and hope to have the study completed in 2018.
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.