Résumé
Lateral positioning decreases upper airway obstruction in sleeping, anesthetized and muscle relaxed individuals presumably secondary to gravitational effects. Children aged 2-6 yr, requiring computed tomography [CT] examination of the head or neck region, were studied using deep sedation with Ketamine/Midazolam 20:1. Exclusion criteria included any type of anatomical or neurologic entity that could influence upper airway shape or size. Axial spiral CT sections of the upper airway were obtained in the supine and lateral positions, with the head and neck axes maintained neutral. Using advanced GE workstation AW4.0, the CT images were processed to render a three-dimensional reconstruction and virtual endoscopic images of the upper airway. Total airway volumes and cross-sectional areas were computed between the nasal vomer and the vocal cords. Two-way paired t tests were used to compare airway sizes between supine and lateral positions. The total airway volume [mean +/- SD] was 6.6 +/- 3.3 ml in the supine position and 9.5 +/- 3.1 ml in the lateral position [P < 0.001] in seventeen of 18 children analyzed. Maximal relative percent airway increase was at the region between the tip of the epiglottis and vocal cords. This study confirms the well-known clinical observation that sedated children practice less upper airway obstruction in the lateral position when compared with the supine position. This widening occurred at all non cartilaginous areas of the upper airway and was most pronounced in the region at and below the tip of the epiglottis