To the Editor:—
An established technique for assessing the anatomical position of the laryngeal mask airway is to pass a fiberoptic scope to the distal end of the airway tube.1An alternative technique, which has become routine practice at one of our institutes, is to use a rigid endoscope that is usually used for laparoscopic surgery. The technique involves disconnecting the extraglottic device from the anesthesia breathing system, adopting the sniffing position to align the glottis and mouth, and advancing a 30° rigid endoscope (Hopkins II Forward-Oblique Telescope; Karl Storz, Tuttlingen, Germany) to the distal end of the airway tube. The high resolution images are then viewed on an external monitor. The rigid endoscope uses a rod-lens optical system (invented in 1959 by Harold H. Hopkins, Ph.D. [1918–1994; Professor in Physics, University Reading, Reading, United Kingdom]) and fiberoptic light transmission (invented in 1960 by Karl Storz, M.D. [1911–1996; Founder Karl Storz GmbH & Co., Tuttlingen, Germany]).2A 6.5-mm-OD rigid endoscope is suitable for adults, and a 3-mm-OD rigid endoscope is suitable for children. The 30° angle allows a greater field of view by simply rotating the scope around its longitudinal axis. It is useful to apply an antifog solution (Aesculap; B. Braun, Tuttlingen, Germany) before insertion, but lubrication is rarely needed. We have used this technique in 600 patients using laryngeal mask and other extraglottic airway devices. In most situations, it was used to evaluate the anatomical position, but in some, it was used to diagnose glottic pathology. The technique has only failed on six occasions, and all of these were related to limited mouth opening preventing full insertion of the endoscope along the airway tube. A potential advantage is the high resolution images (fig. 1). Potential disadvantages are the risk of dental trauma and displacement of the extraglottic device; however, to date, these problems have not occurred. Finally, the technique is unsuitable for extraglottic devices with rigid or narrow airway tubes, such as the intubating or ProSeal ™ (Laryngeal Mask Company, Ltd., Nicosia, Cyprus) laryngeal mask airways, respectively.
*Catharina Hospital–Brabant Medical School, Eindhoven, The Netherlands. email@example.com