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 com mon problem during general anesthesia. Chin lift is a commonly used techniq ue to improve upper airway patency, However, little is known about the mech anism 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 w ith propofol during routine magnetic resonance imaging, The minimal anterop osterior and corresponding transverse diameters of the pharynx were determi ned 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-se ctional areas were calculated at these sites, including tracheal areas 2 cm below the glottic level. Results: Minimal anteroposterior diameter of the pharynx Increased signific antly during chin lift at all three levels in all patients. The diameters o f 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 di ameter of the pharynx also increased significantly at all three levels In a ll patients but without significant predominance. The diameters at the leve ls of the soft palate, tongue, and epiglottis increased from 15.8 +/- 5.1 m m 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 a reas 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 c m(2)). Conclusions: This study shows that all children had a preserved upper airwa y at all measured sites during propofol sedation. Chin lift caused a wideni ng 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.