Effect of combined mouth closure and chin lift on upper airway dimensions during routine magnetic resonance imaging in pediatric patients sedated with propofol

Background: in pediatric patients, obstruction of the upper airway is a common problem during general anesthesia. Chin lift is a commonly used technique to improve upper airway patency, However, little is known about the mechanism underlying this technique. Methods: The authors studied the effect of the chin lift maneuver on airway dimensions in 10 spontaneously breathing children (aged 2-11 yr) sedated with propofol during routine magnetic resonance imaging, The minimal anteroposterior and corresponding transverse diameters of the pharynx were determined at the levels of the soft palate, dorsum of the tongue, and tip of the epiglottis before and during the chin lift maneuver. Additionally, cross-sectional areas were calculated at these sites, including tracheal areas 2 cm below the glottic level. Results: Minimal anteroposterior diameter of the pharynx Increased significantly during chin lift at all three levels in all patients. The diameters of the soft palate, tongue, and epiglottis increased from 6.7 +/- 2.8 mm (SD) to 9.9 +/- 3.6 mm, from 9.6 +/- 3.6 mm to 16.5 +/- 3.1 mm, and from 4.6 +/- 2.5 mm to 13.1 +/- 2.8 mm, respectively. The corresponding transverse diameter of the pharynx also increased significantly at all three levels In all patients but without significant predominance. The diameters at the levels of the soft palate, tongue, and epiglottis increased from 15.8 +/- 5.1 mm to 22.8 +/- 4.5 mm, from 13.5 +/- 4.9 mm to 18.7 +/- 5.3 mm, and from 17.2 +/- 3.9 mm to 21.2 +/- 3.7 mn, respectively. Cross-sectional pharyngeal areas increased significantly at all levels (soft palate, from 0.88 +/- 0.58 cm(2) to 1.79 +/- 0.82 cm(2); tongue, from 1.15 +/- 0.45 cm(2) to 2.99 +/- 1.30 cm(2); epiglottis, from 1.17 +/- 0.70 cm(2) to 3.04 +/- 0.99 cm(2)), including the subglottic level (from 0.44 +/- 0.15 cm(2) to 0.50 +/- 0.14 cm(2)). Conclusions: This study shows that all children had a preserved upper airway at all measured sites during propofol sedation. Chin lift caused a widening of the entire pharyngeal airway that was most pronounced between the tip of the epiglottis and the posterior pharyngeal wall. In pediatric patients, chin lift may be used as a standard procedure during propofol sedation.