The usefulness of the modified laryngoscopic blade for training novice laryngoscopists

Abstract

Study Objective The objective of this study was to evaluate the effectiveness of a modified Macintosh blade for reducing the chances of directly contacting the teeth and providing a satisfactory laryngoscopic view during laryngoscopies by novice laryngoscopists. Design This is a prospective clinical comparison study. Setting The study took place at an operating room of a university hospital. Patients Seventy-two patients with American Society of Anesthesiologists physical statuses I and II, aged 16 to 64 years, who were scheduled for elective surgery requiring general anesthesia with endotracheal tube placement participated in this study. Interventions Laryngoscopy was performed twice on each patient, once with a regular Macintosh no. 3 blade and once with a blade in which the flange was partially removed. Measurements As an indirect parameter for anticipating potential dental injury during laryngoscopy, the perpendicular distance from the tip of the maxillary central incisor to the flange of each blade (the blade-tooth distance) was measured when a novice laryngoscopist lifted up the laryngoscope and visualized the glottis. We compared the blade-tooth distances, the chances of directly contacting the tooth, laryngoscopic views, and the subjective feeling of difficulty in handling the laryngoscope between the 2 blades. Main Results Blade-tooth distance varied significantly between the 2 blades: the median/interquartile range was 1.2/2.3 mm vs 3.0/4.3 mm for the regular Macintosh no. 3 and the modified blade, respectively ( P < .01). The modified blade was associated with decreased chances of directly contacting the teeth ( P < .05). In addition, the modified blade provided a better laryngoscopic view than did the regular blade ( P < .01). Most novice laryngoscopists felt that laryngoscopy with the modified blade was significantly easier than that with the regular Macintosh blade ( P < .01). Conclusions The modified Macintosh blade used in this study proved to be a useful device for training novice laryngoscopists with respect to procedure effectiveness and patient safety.