Fiberoptic Laryngoscopic View of the Laryngeal Mask Airway Placed in the Hypopharynx

Kim, Woo Sun; Lee, Sang Kyi; Yoo, Chun Won; Ko, Seong Hoon

Abstract

BACKGROUND: The laryngeal mask airway (LMA) should be correctly placed into the hypopharynx for adequate ventilation. The purpose of this study was to evaluate a LMA position relation to the laryngeal skeleton and narrowing degree of a LMA lumen by the epiglottis.
METHODS
The LMA (# 3 or # 4) was placed into the hypopharynx after induction of anesthesia and muscle paralysis. The fiberoptic laryngoscopic findings through the lumen of LMA were recorded at ten minutes after LMA placements. The position of the LMA was estimated in relation to its distal aperture to the laryngeal skeleton as central, posterior, right and left lateral position. The narrowing degree of the LMA by the epiglottis was estimated as 0%, 1~25%, 26~50%, 51~75%, or 76~100%.
RESULTS
The fiberoptic laryngoscope showed central positions in 70.1%, lateral deviations to the left or right in 21.2% and posterior positions in 9%. The most frequent incidence (84/231, 36.4%) of narrowing by the epiglottis is 76~100% but ventilating problems were not developed. However, ventilation was impossible immediately after LMA placement in one patient, so the LMA was removed and the trachea was intubated. Esophageal enterance was visible in one patient without regurgitation of the stomach content.
CONCLUSIONS
These findings show that LMA provides a reliable and safe airway management technique, although inadequate positioning and narrowing of LMA lumen by the epiglottis may frequently occur.