Use of Direct Laryngoscope Improves a Hypopharyngeal Position of Laryngeal Mask Airway

Lee, Younsuk; Cho, Byoung Woo; Oh, Yong Seok; Lee, Kook Hyun; Ko, Hong; Kim, Kwang Woo

Abstract

BACKGROUND: Laryngeal mask airway (LMA) partly can be replaced for a role of endotracheal tube intraoperatively. Even with selecting one from various insertion techniques of LMA, one cannot achieve its perfect hypopharyngeal position. Furthermore, which is chosen by most anesthesiologists in this country, use of muscle relaxant for LMA insertion appears to have a harmful effect on its position. We tried to confirm whether we can improve the hypopharyngeal position of LMA with additional elevation of epiglottis using direct laryngoscope during LMA insertion.
METHODS
Forty healthy patients scheduled for surgical procedure under general anesthesia were randomly divided to two groups; Laryngoscope group (n=20) and Jaw thrust group (n=20). No premedicant was administered. Anesthesia was induced with thiopental, vecuronium plus 2~3 vol% enflurane in oxygen. Full muscular relaxation was judged by no adductor response of thumb to train-of-four stimuation. In Jaw thrust group, using Brain's standard technique with additional jaw thrust, LMA was inserted, while in Laryngoscope group, LMA was introduced into oral cavity and advanced farther with additional elevation of epiglottis with direct laryngoscope. Bronchoscopic grading of hypopharyngeal position of LMA was performed. Blood pressure and heart rate were recorded at arrival (control), preintubation and until postintubation 5 minutes at 1 minute interval. Each measured values were compared between groups.
RESULTS
Bronchoscopic grade of Laryngoscope group was significantly better than that of Jaw thrust group (p<0.001). Mean arterial pressure and heart rate changes were not different between groups.
Conclusion
In the case of LMA insertion using muscle relaxant, we can markedly improve the hypopharyngeal placement of LMA with help of direct laryngoscope.