Oral Dexmedetomidine in Pediatric MRI

MRI is an important and robust medical imaging technique that has become the cornerstone for radiologic studies. Superior image quality and resolution especially for soft tissue imaging, without the use of ionizing radiation, has made MRI a dominant imaging modality in pediatrics. Despite its many advantages, MRI is not child friendly. Lengthy scan times, the need for lying motionless in a confined space, excessive noise and vibration during image acquisition, are all factors that have made anesthesia an integral part of pediatric MRI.

General anesthesia is a state of medically induced unconsciousness, analgesia and muscle relaxation which is required for most invasive medical procedures. Despite being painless, MRI scans are highly susceptible to motion artifact and require a state of immobility that may not be obtainable in awake uncooperative children. While very safe, general anesthesia carries potential risk of serious morbidity and mortality secondary to aspiration during instrumentation of the airway, hypoxia and hypoventilation secondary to laryngospasm/bronchospasm and hemodynamic instability. Therefore, sedation may be an appropriate technique to offer anxiolysis, amnesia and immobility while maintaining airway reflexes with limited impact on ventilation and hemodynamics for non-stimulating procedures such as imaging. Aside from having a more favorable risk/benefit profile as compared to general anesthesia when it comes to radiologic studies, sedation is also less costly and burdensome on anesthesia departments and could provide immense cost-saving measures for healthcare institutions at large.

While there are many intravenous (IV) sedatives, establishing IV access while awake could be very traumatizing, leaving a lasting negative impression of the healthcare environment in a child's mind. Hence, enteral medications may be more acceptable and child friendly. This is especially valuable in patients who require repeated surveillance imaging and who demonstrate heightened level of anxiety and fear with each visit. Among sedative agents that could be administered enterally, dexmedetomidine may be superior due to minimal respiratory depression while providing anxiolysis and analgesia. Of note, dexmedetomidine is a highly selective alpha2-adrenoreceptor agonist that exerts its hypnotic action through activation of central pre- and postsynaptic alpha2-receptors in the locus coeruleus, mimicking natural sleep.

Inclusion criteria

• Participants 3-6 years old, male and female, all races and ethnicities
• Requiring a clinically indicated MRI with general anesthesia

Exclusion criteria

• Refusal to take oral dexmedetomidine
• Known allergy to dexmedetomidine
• Inability to take dexmedetomidine at least 90 minutes prior to start of the MRI
• Medical contraindications to administration of dexmedetomidine including:

• Unstable cardiac status including life threatening arrhythmias, abnormal cardiac anatomy, significant cardiac dysfunction
• Current use of digoxin
• Moya Moya disease
• New onset stroke
• American Society of Anesthesiologists (ASA) physical status classification > II
• Contraindications to administering sedation including:

• Active and uncontrolled gastroesophageal reflux
• Active and uncontrolled vomiting
• Current or recent history of apnea
• Active respiratory disease including pneumonia, bronchitis, respiratory syncytial virus infection, asthma exacerbation
• Craniofacial anomalies
• Inability to have MRI scans
• Non-English speaking volunteers