This is a pilot study to determine if a standard bolus dose and infusion of dexmedetomidine can significantly decrease the dose of propofol (infusion) required for accomplishing an MRI. The investigators studied three arms to examine the effectiveness of dexmedetomidine. Arm 1 was a single bolus of 1.0 mcg/kg with 1.0 mcg/kg/hr infusion followed by propofol infusion. Arm 2 was a bolus of 1.0 mcg/kg with 0.5 mcg/kg/hr infusion followed by propofol infusion. Arm 3 was only a single bolus of 1.0 mcg/kg with no infusion followed by propofol infusion.
A recent publication in the New England Journal of Medicine highlighted the accumulating evidence for neurotoxic effects of anesthetics in animal models and a collection of epidemiologic studies in humans. Recent studies of anesthesia in fetal and neonatal primates are yielding more evidence of neurotoxicity associated with many common anesthesia and sedation techniques (e.g. propofol, etomidate, sevoflurane, desflurane and isoflurane). On the other hand, the data suggests that some alternative sedative agents, such as Dexmedetomidine, may not have the same neurotoxic effect. Children routinely undergo sedation for MRI scanning with large doses of propofol and other sedatives. Many of these scans occur at young ages when these children may be at risk of neurological injury from sedative exposure. In addition, these scans do not involve any stimulation - which could be protective against neurodegeneration. The investigators propose a pilot study to determine if a standard bolus dose and infusion of dexmedetomidine can significantly decrease the dose of propofol (infusion) required for accomplishing an MRI. Based on previous work with the combination of propofol with dexmedetomidine for other procedures, the investigators propose a standard dose of dexmedetomidine (1 mcg/kg bolus followed by an infusion at 1.0 mcg/kg/hour, 0.5 mcg/kg/hour, or no infusion). The investigators will augment this sedation with propofol 2-3 mg/kg titrated bolus followed by 100 mcg/kg/min infusion which can also be titrated up or down to a maximum of 300 mcg/kg/min to keep the blood pressure and heart rate within 30% of baseline levels). The investigators hypothesize that the use of low dose propofol with dexmedetomidine will be effective undergoing MRI while sparing exposure to the high dose of the sedative.
Study Type
INTERVENTIONAL
Allocation
NON_RANDOMIZED
Purpose
HEALTH_SERVICES_RESEARCH
Masking
NONE
Enrollment
71
First, the investigators will administer dexmedetomidine 1mcg/kg over 5 minutes. Next, the investigators will begin an infusion at 1mcg/kg/hour. At the 5 minute point, propofol will be given (2-3mg/kg bolus followed by 100mcg/kg/min infusion). The attending clinician will determine whether or not the child is in an adequate state to begin the MRI scan. If the sedative effect of the dexmedetomidine-propofol does not produce a sufficiently sedated state within 10 minutes, a repeat bolus of propofol 2mg/kg will be administered. The dose of Dexmedetomidine will not be changed. The dose will be repeated if the child is not adequately sedated in 2 more minutes. At this time infusion rate of propofol will be increased to 200 mcg/kg/minute. If the child is not sedated in 5 more minutes, the outcome will be recorded as a technique failure and sedation will continue at the discretion of the anesthesiologist.
First, the investigators will administer dexmedetomidine 1mcg/kg over 5 minutes. Next, the investigators will begin an infusion at 0.5mcg/kg/hour. At the 5 minute point, propofol will be given (2-3mg/kg bolus followed by 100mcg/kg/min infusion). The attending clinician will determine whether or not the child is in an adequate state to begin the MRI scan. If the sedative effect of the dexmedetomidine-propofol does not produce a sufficiently sedated state within 10 minutes, a repeat bolus of propofol 2mg/kg will be administered. The dose of Dexmedetomidine will not be changed. The dose will be repeated if the child is not adequately sedated in 2 more minutes. At this time infusion rate of propofol will be increased to 200 mcg/kg/minute. If the child is not sedated in 5 more minutes, the outcome will be recorded as a technique failure and sedation will continue at the discretion of the anesthesiologist.
First, the investigators will begin by administering dexmedetomidine 1mcg/kg over 5 minutes. When this is completed, they will administer propofol 2-3mg/kg titrated bolus followed by 100mcg/kg/min infusion which can also be titrated up or down to a maximum of 300mcg/kg/min to keep the blood pressure and heart rate within 30% of baseline levels.
Boston Children's Hospital
Boston, Massachusetts, United States
Dosage/Consumption
Dosage and consumption of dexmedetomidine infusion
Time frame: Prior to beginning the MRI and throughout the MRI scan - approximately one hour.
Incidence of Patient Movement and MRI Interruption
If patient moved during their MRI and caused an interruption of the scan.
Time frame: During the MRI scan, until completion, approximately one hour.
Incidence of Adverse Events
arterial desaturation, airway obstruction, hypotension and bradycardia
Time frame: From the time the medication is initiated just (5 minutes) prior to the MRI scan and during the MRI scan and immediately during recovery - approximately one hour and twenty minutes in total.
Case Times
Number of minutes from the start of sedation medication administration to the time the patient is adequately sedated for the MRI scan,
Time frame: Timeframe immediately before the MRI scan while sedation medication is administered - approximately 10 minutes
Incidence of Technique Failure
lack of adequate sedation for MRI scan in spite of the sedation as described above
Time frame: During the MRI scan until completion - approximately one hour
Sedation Infusion Time
The number of minutes that the patient was receiving dexmedetomidine infusion
Time frame: For the duration of the MRI scan - approximately one hour
Case Duration
total number of minutes in the MRI scanner,
Time frame: Duration of the MRI scan - approximately one hour
Recovery Time
number of minutes in the recovery area until the patient appeared awake (eye opening),
Time frame: from completion of the MRI scan until prepared for discharge - approximately 90 minutes
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