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The most common imaging procedure requiring sedation/anesthesia for the pediatric population is magnetic resonance imaging (MRI). However, the optimal anesthetic/sedation plan has not been determined for these procedures. Historically, common medications have included the use of pentobarbital and propofol, but in 2015, publication in the New England Journal of Medicine highlighted the accumulating evidence for the possible neurotoxic effects of these types of anesthetics in animal models and a collection of epidemiologic studies in humans. Although these initial possibilities have since been proven as less of a concern, in the interim, data has shown that alternative sedative agents, such as dexmedetomidine, may not have the same neurotoxic effect and could possibly even provide neuroprotection. Dexmedetomidine also possesses other beneficial traits such as reducing risks of pulmonary atelectasis or upper airway collapse, typically found with the administration of propofol.
A concern raised by previous studies has been the possibility that the addition of dexmedetomidine could increase recovery times, leading to disruptions in workflow. Although it has been shown that large doses of dexmedetomidine exposure may lead to longer PACU stays, it is uncertain whether a small dose of dexmedetomidine would have such a significant impact. Based on the investigators' pilot trial6, the investigators found that a bolus of 1 mcg/kg dose of dexmedetomidine with a bolus of titrated propofol of 2-3 mg/kg and an infusion of propofol of 100 mcg/kg/min provided adequate sedation for successful scans, reduced propofol (infusion) exposure by 60%, and did not significantly increase recovery times.
Finally, there is a paucity in literature for studies examining a range of doses subsequently; often, a control group is compared to a single, self-selected dose of choice. Here, the investigators hope to provide a range of doses to minimize selection bias in our study design and determine the dose that would provide the optimal sedation for these scans and minimize excess anesthetic exposure.
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| Label | Type | Description | Intervention Names |
|---|---|---|---|
| Propofol Only (P) | Active Comparator | 1 mg/kg (max 25 kg) of IV lidocaine (standard of care) will be given. 2-4 mg/kg titrated bolus of propofol will be administered, which can be repeated 2x until a Ramsay Sedation Score of 5-6 is achieved. After that, 250 mcg/kg/min infusion of propofol will be initiated and can be titrated up to a maximum of 300 mcg/kg/min to maintain a Ramsay Sedation Score of 5-6. If not sedated after 5 more minutes, record a technique failure and continue sedation at anesthesiologist's discretion. Per standard of care, the propofol infusion may be decreased if the blood pressure decreases by more than 30% from lowest expected norms or if there is any indication of possible airway obstruction. |
|
| Dexmedetomidine (high)-Propofol (DHP) | Active Comparator | 1 mcg/kg dexmedetomidine (DEX) bolus over 5-10 minutes will be delivered by fractionated doses or infusion. After the DEX bolus is complete, 1 mg/kg (max 25 mg) of IV lidocaine will be administered followed by a dose of 2-3 mg/kg titrated bolus of propofol (P), which can be repeated 2x until a Ramsay Sedation Score of 5-6 is achieved. After this, 150 mcg/kg/min infusion of P will be initiated. If the Ramsay Sedation score of 5-6 is not achieved within 2 minutes, 1-2 mg/kg bolus of P may be administered and P infusion will be increased to 200 mcg/kg/min. The P infusion can be titrated up to a maximum of 300 mcg/kg/min if needed to maintain a Ramsay Sedation Score of 5-6. If not sedated after 5 more minutes, record a technique failure and continue sedation at anesthesiologist's discretion. Per standard of care, the propofol infusion may be decreased if the blood pressure decreases by more than 30% from lowest expected norms or if there is any indication of possible airway obstruction. |
|
| Dexmedetomidine (low)-Propofol (DLP) |
| Name | Type | Description | Arm Group Labels | Other Names |
|---|---|---|---|---|
| Dexmedetomidine (IV) 0.5 mcg/kg | Drug | If patient is randomized to the DLP arm, patient will receive an IV bolus of 0.5 mcg/kg dexmedetomidine over 5 minutes. |
|
| Measure | Description | Time Frame |
|---|---|---|
| Total Propofol (mcg/kg/min) consumption | The total amount of propofol (mcg/kg/min) consumed will be measured for the duration of anesthesia time for the P, DLP, and DHP arms. | Up to 120 minutes or from induction of anesthesia/sedation to end of MRI scan |
| Measure | Description | Time Frame |
|---|---|---|
| Peak Pediatric Anesthesia Emergence Delirium (PAED) Score | The peak (highest) PAED score will be obtained in the post-anesthesia recovery area (PACU). | Up to 180 minutes or duration of PACU stay |
| Incidence of Adverse Events |
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Inclusion Criteria:
Exclusion Criteria:
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| Name | Role | Phone | Extension | |
|---|---|---|---|---|
| Samuel Kim, BS | Contact | 617-919-3692 | samuel.kim@childrens.harvard.edu | |
| Rachel Bernier, MPH | Contact | 857-218-5348 | rachel.bernier@childrens.harvard.edu |
| Name | Affiliation | Role |
|---|---|---|
| Joseph Cravero, MD | Boston Children's Hospital | Principal Investigator |
| Facility | Status | City | State | ZIP | Country | Contacts |
|---|---|---|---|---|---|---|
| Boston Children's Hospital | Recruiting | Boston | Massachusetts | 02115 | United States |
| PubMed Identifier | Type | Citation | Retractions |
|---|---|---|---|
| 29882298 | Background | Nagoshi M, Reddy S, Bell M, Cresencia A, Margolis R, Wetzel R, Ross P. Low-dose dexmedetomidine as an adjuvant to propofol infusion for children in MRI: A double-cohort study. Paediatr Anaesth. 2018 Jul;28(7):639-646. doi: 10.1111/pan.13400. Epub 2018 Jun 7. | |
| 36620110 | Background | Ramaprasannakumar SK, Bhadrinarayan V, Venkataramaiah S. The Effectiveness of Three Regimens of Sedation for Children Undergoing Magnetic Resonance Imaging: A Clinical Study. Anesth Essays Res. 2022 Jul-Sep;16(3):345-352. doi: 10.4103/aer.aer_45_22. Epub 2022 Dec 9. |
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| Active Comparator |
0.5 mcg/kg dexmedetomidine (DEX) bolus over 5-10 minutes will be delivered by fractionated doses or infusion. After the DEX bolus is complete, 1 mg/kg (max 25 mg) of IV lidocaine will be administered followed by a dose of 2-3 mg/kg titrated bolus of propofol (P), which can be repeated 2x until a Ramsay Sedation Score of 5-6 is achieved. After this, 150 mcg/kg/min infusion of P will be initiated. If the Ramsay Sedation score of 5-6 is not achieved within 2 minutes, 1-2 mg/kg bolus of P may be administered and P infusion will be increased to 200 mcg/kg/min. The P infusion can be titrated up to a maximum of 300 mcg/kg/min if needed to maintain a Ramsay Sedation Score of 5-6. If not sedated after 5 more minutes, record a technique failure and continue sedation at anesthesiologist's discretion. Per standard of care, the propofol infusion may be decreased if the blood pressure decreases by more than 30% from lowest expected norms or if there is any indication of possible airway obstruction. |
|
|
| Propofol (IV) 2-4 mg/kg | Drug | If patient is randomized to the P arm, patient will receive 2-4 mg/kg titrated, IV bolus of propofol until sleep is induced. |
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| Dexmedetomidine (IV) 1 mcg/kg | Drug | If patient is randomized to the DHP arm, patient will receive an IV bolus of 1 mcg/kg dexmedetomidine over 5 minutes. |
|
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| Propofol (IV) 1-2 mg/kg | Drug | If the patient is randomized to the DLP or DHP arm, following the dexmedetomidine bolus, the patient will receive a titrated, IV bolus of 1-2 mg/kg propofol. |
|
|
| Propofol (IV) Infusion 250 mcg/kg/min | Drug | If the patient is randomized to the P arm, following the bolus of propofol, the patient will be started on an IV propofol infusion of 250 mcg/kg/min. |
|
|
| Propofol (IV) Infusion 150 mcg/kg/min | Drug | If the patient is randomized to the DLP or DHP arm, following the titrated propofol bolus, the patient will be started on an IV propofol infusion of 150 mcg/kg/min. |
|
|
Arterial desaturation, airway obstruction, hypotension and bradycardia
| Up to 240 minutes or from induction of anesthesia/sedation to immediately during recovery |
| Incidences of Patient Movements/MRI Interruptions | If patient moved during their MRI and caused an interruption of the scan. | Up to 90 minutes or duration of MRI scan |
| Incidence of Technique Failure | Lack of adequate sedation for MRI scan in spite of the sedation as described above (based on anesthesiologist's discretion or PSSS) | Up to 120 minutes or from induction of anesthesia/sedation to end of MRI scan |
| Case Duration | Total number of minutes in the MRI scanner | Up to 90 minutes or duration of MRI scan |
| Post Anesthesia Care Unit (PACU) Duration | Total number of minutes in the PACU | Up to 180 minutes or duration of PACU stay |
| Ramsay Sedation Score | Average Ramsay Sedation Score | 10 minutes or from anesthesia induction to MRI scan start |
| 27779360 | Background | Boriosi JP, Eickhoff JC, Klein KB, Hollman GA. A retrospective comparison of propofol alone to propofol in combination with dexmedetomidine for pediatric 3T MRI sedation. Paediatr Anaesth. 2017 Jan;27(1):52-59. doi: 10.1111/pan.13041. Epub 2016 Oct 25. |
| 34036674 | Background | Vinson AE, Peyton J, Kordun A, Staffa SJ, Cravero J. Trends in Pediatric MRI sedation/anesthesia at a tertiary medical center over time. Paediatr Anaesth. 2021 Sep;31(9):953-961. doi: 10.1111/pan.14225. Epub 2021 Jun 22. |
| 40349256 | Background | Kim SY, Booth JM, Staffa SJ, Kordun A, Yu J, Cravero JP. A dose-ranging pilot trial of dexmedetomidine-propofol in children undergoing magnetic resonance imaging. J Anesth. 2025 Dec;39(6):989-994. doi: 10.1007/s00540-025-03511-z. Epub 2025 May 11. |
| 25714157 | Background | Rappaport BA, Suresh S, Hertz S, Evers AS, Orser BA. Anesthetic neurotoxicity--clinical implications of animal models. N Engl J Med. 2015 Feb 26;372(9):796-7. doi: 10.1056/NEJMp1414786. |
| 36173243 | Background | Mallory MD, Travers C, Cravero JP, Kamat PP, Tsze D, Hertzog JH. Pediatric Sedation/Anesthesia for MRI: Results From the Pediatric Sedation Research Consortium. J Magn Reson Imaging. 2023 Apr;57(4):1106-1113. doi: 10.1002/jmri.28392. Epub 2022 Aug 12. |
| ID | Term |
|---|---|
| D000071257 | Emergence Delirium |
| ID | Term |
|---|---|
| D003693 | Delirium |
| D003221 | Confusion |
| D019954 | Neurobehavioral Manifestations |
| D009461 | Neurologic Manifestations |
| D009422 | Nervous System Diseases |
| D011183 | Postoperative Complications |
| D010335 | Pathologic Processes |
| D013568 | Pathological Conditions, Signs and Symptoms |
| D012816 | Signs and Symptoms |
| D019965 | Neurocognitive Disorders |
| D001523 | Mental Disorders |
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| ID | Term |
|---|---|
| D020927 | Dexmedetomidine |
| D015742 | Propofol |
| ID | Term |
|---|---|
| D007093 | Imidazoles |
| D001393 | Azoles |
| D006573 | Heterocyclic Compounds, 1-Ring |
| D006571 | Heterocyclic Compounds |
| D010636 | Phenols |
| D001555 | Benzene Derivatives |
| D006841 | Hydrocarbons, Aromatic |
| D006844 | Hydrocarbons, Cyclic |
| D006838 | Hydrocarbons |
| D009930 | Organic Chemicals |
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