Effect of increasing depth of dexmedetomidine anesthesia on upper airway morphology in children

Objective: This prospective study examines the dose-response effects of dexmedetomidine on upper airway morphology in children with no obstructive sleep apnea (OSA). Aim: To determine the effect of increasing doses of dexmedetomidine on static and dynamic magnetic resonance (MR) images of the upper airway in spontaneously breathing children with no OSA. Background: General anesthetics and sedatives attenuate upper airway muscle activity, rendering the airway vulnerable to obstruction. Dose-response effects of dexmedetomidine on upper airway of children are not known. We prospectively examined the dose-response effects of dexmedetomidine on upper airway morphology in children. Methods/Materials: Increasing doses of dexmedetomidine was administered to 23 children scheduled for MR imaging of the brain while breathing spontaneously via the native airway. Static axial and dynamic sagittal midline MR cine images of the upper airway were obtained during low (1 mcg.kg(-1).h(-1)) and high (3 mcg.kg(-1).h(-1)) doses of dexmedetomidine. The airway anteroposterior diameter, transverse diameter, and cross-sectional areas were measured manually by two independent observers. Static airway measurements were taken at the level of the nasopharyngeal airway (sagittal images) and retroglossal airway (RGA) (sagittal and axial images). Dynamic change in cross-sectional area of airway between inspiration and expiration was considered a measure of airway collapsibility. Results: Static axial measurements of RGA did not change with increasing dose of dexmedetomidine. Most sagittal airway dimensions demonstrated clinically modest, although statistically significant, reductions with high dose compared to low dose dexmedetomidine. Although, the dynamic changes in nasopharyngeal and retroglossal area with respiration were marginally greater for high dose than for low dose dexmedetomidine, no subject exhibited any clinical evidence of airway obstruction. Conclusion: Upper airway changes associated with increasing doses of dexmedetomidine in children with no OSA are small in magnitude and do not appear to be associated with clinical signs of airway obstruction. Even though these changes are small, all precautions to manage airway obstruction should be taken when dexmedetomidine is used for sedation.