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

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.

Metric Study of Upper Airway and Trachea in Nomal Korean Adults uing Fiberoptic Bronchoscopy: Study of endotracheal tube fixation positioning in adults / 대한마취과학회지

BACKGROUND: Neck flexion risks endobroncheal intubation when the tracheal tube is not in the proper position. So accurate knowledge of upper airway length is required to prevent malpositioning of endotracheal tubes. Therefore we evaluated the length of various portions of upper airway in Korean adults (n=500) who had no abnormality of upper airway. METHODS: Five hundred patients, composed of 198 males and 302 females who underwent elective surgery, were included in this study. After endotracheal tube was placed under general anesthesia, we measured the distance from tube machine-end to upper incisor (value 1), from tube machine-end to inferior margin of cricothyroid membrane (value 2), and from tube machine-end to carina (value 3) by means of fiberoptic bronchoscopy. RESULTS: The mean length between upper incisor and inferior margin of cricothyroid membrane (value 2 - value 1) was 12.7 cm in males and 11.6 cm in females, while the mean length between superior margin of cricoid cartilage and carina (value 3 - value 2) was 12.9 cm in males and 11.3 cm in females. So the mean length between upper incisor and the mid portion of trachea was nearly 19.6 cm in males and 17.7 cm in females. CONCLUSIONS: We believe that, based on the findings in this study, the safety length for endotracheal tube fixation is 20 cm in Korean adult males and 18 cm in Korean adult females.