Use of Macintosh Laryngoscope No. 2 for Adult Patients with a Short Thyromental Distance

Abstract

takenaka.i@ns.yawata-mhp.or.jpWe read with great interest the article by Tripathi and Pandey1reporting that the use of the Macintosh laryngoscope No. 3 (Mac #3) in patients with a short thyromental distance was associated with great difficulty in laryngoscopy and intubation compared with the Mac #2. We previously assessed the laryngeal aperture fiberoptically during direct laryngoscopy with the Mac #3 in 17 patients whose glottis was invisible under direct vision (difficult laryngoscopy).2In one fourth of these patients, the laryngoscope could not provide an adequate fiberoptic view of the laryngeal aperture because of an inability to lift the collapsed laryngeal tissues caused by general anesthesia and the muscle relaxant.3That is, in these patients, it is difficult to place the blade tip of the Mac #3 in the position necessary to lift the epiglottis and the laryngeal soft tissues. The authors clarified this problem by measuring the intubation distance and overcame it by using the Mac #2 with its thinner flange and greater curvature of the spatula. We respect their ideas. However, adult patients whose airway is predicted as difficult by a short thyromental distance have a small mandible, but the size of their maxilla is usually normal (defined as micrognathia), which is different from pediatric patients. Moreover, they often have protruding upper incisors. Thus, we are concerned that when the Mac #2, which is 1.5–2 cm shorter than the Mac #3, is used with these patients, the whole blade gets into the oral cavity, and a good laryngoscopic view is not obtained even if the blade tip reaches the optimal position required to lift the laryngeal soft tissues.*Nippon Steel Yawata Memorial Hospital, Kitakyushu, Japan.takenaka.i@ns.yawata-mhp.or.jp