Airway Dimension Study in Children Undergoing MRI Sedated With Propofol and Dexmedetomidine

Comparison of Changes in Upper Airway Dimensions With Dexmedetomidine and Propofol in Children Undergoing MRI

Sedation is required in infants and children to successfully complete MRI while maintaining respiratory and hemodynamic stability. Limited access to the patient may pose a safety risk during MRI examination. Therefore, appropriate drugs need to be selected, administered, and titrated to achieve these objectives. Propofol is commonly used for sedation in children in the MRI setting because of its predictability, rapid onset, and offset of action. Dexmedetomidine has sedative and analgesic properties without affecting cardiovascular and respiratory stability. The rationale of this research is to assess the effect of these drugs on the upper airway and validate their use in children with upper airway disorders.

Objectives The objective of this study is to compare the changes in upper airway configuration at the level of soft palate, base of tongue and tip of the epiglottis in children sedated with dexmedetomidine and propofol in children undergoing MRI. We hypothesize that the upper airway caliber will be smaller in children receiving propofol than with dexmedetomidine. Primary Outcome To measure the cross-sectional area (CSA) of the upper airway at the level of soft palate, base of the tongue and epiglottis in both groups of children at high doses of propofol and dexmedetomidine and thus compare the decrease in CSA with increasing doses of both drugs. Secondary Outcomes To measure the anteroposterior (AP) diameter transverse (Tr) diameter of the upper airway at the three levels in both groups of children at both low and high doses of propofol and dexmedetomidine and compare the decrease in AP and Tr diameter at increasing doses of dexmedetomidine.

Administer dexmedetomidine at 1mcg/kg over 10min followed by an infusion of dexmedetomidine at 1mcg/kg/hr and image the upper airway. After the initial set of images is obtained, the depth of anesthesia will be increased by administering a bolus dose of dexmedetomidine 2mcg/kg followed by increase in the infusion rate to 3mcg/kg/hr. Upper airway images will be repeated 5mins after increasing infusion Image acquisitions will be repeated approximately 5 min after the increase in infusion rate.

Administer propofol bolus at 2mg/kg,followed by an infusion of propofol at 100 mcg/kg/min. Upper airway images will be obtained 5 mins after the patient is stable on this infusion. After the initial set of images is obtained, the depth of anesthesia will be increased by administering a bolus dose of 1mg/kg propofol and infusion increased to 240mcg/kg/min. Image acquisitions will be repeated approximately 5 min after the increase in infusion rate.

Cross-sectional Area (CSA) of the Upper Airway at the Level of Soft Palate, Base of the Tongue and Tip of the Epiglottis

At each anatomic level, measurements will be obtained during three successive respiratory cycles and values will be averaged.

When expired sevoflurane is 0% during the procedure on an average of 5 - 10 mins after discontinuation of sevoflurane, airway measurements will be done

Anteroposterior Diameter of the Airway at the Level of Soft Palate, Base of Tongue and Tip of the Epiglottis

At each anatomic level, measurements will be obtained during three successive respiratory cycles and values will be averaged

When the the expired sevoflurane is 0% during the procedure on an average of 5 - 10 min after discontinuation of devoflurane, measurement will be obtained

Transverse Diameter of the Airway at the Level of Soft Palate, Base of Tongue and Tip of the Epiglottis

At each anatomic level, measurements will be obtained during three successive respiratory cycles and values will be averaged

When the the expired sevoflurane is 0% during the procedure on an average of 5 - 10 min after discontinuation of sevoflurane, measurement will be obtained

Inclusion Criteria: Children undergoing MRI brain Age 2 - 5 yrs ASA I - II Exclusion Criteria: OSA Pathology of upper airway Craniofacial anomalies Gastroesophageal reflux Increased intracranial pressure Body weight of 20% more than ideal Contraindication to the use of either drug Failure to maintain a patent airway during the study