We read with interest the article by Karsli et al. [1], which demonstrated the usefulness of the paediatric GlideScope® video laryngoscope (Verathon Medical Inc., Bothell, WA, USA) in children with a difficult airway, relative to conventional direct laryngoscopy using the Macintosh blade. We agree with the authors’ view that the backward, upward and right-sided pressure on the larynx provides better glottic exposure using the paediatric GlideScope. 

 

Overall, the paediatric GlideScope, with or without the backward, upward and right-sided pressure manoeuvre, provided a better glottic view than the Macintosh laryngoscope in the same study [1]. However, in 6 of their 18 children, the use of the paediatric GlideScope without the backward, upward and right-sided pressure  manoeuvre provided a view of the glottis that was equal to or worse than that provided by the Macintosh laryngoscope, without the backward, upward and right-sided pressure manoeuvre (Cormack-Lehane grade 3 and 4). Even when the GlideScope was used with the backward, upward and right-sided pressure manoeuvre, it provided a worse view (grade 3 and 4 versus grade 2 and 3) in two children, and a similar view to that by the Macintosh laryngoscope (grade 3) in one child. 

 

We had similar cases in which a worse view of the glottis was obtained using the paediatric GlideScope than with the Macintosh laryngoscope [2]. The GlideScope exposes the glottic opening through the Complementary Metal Oxide Semiconductor camera, which is placed at the front of the glottis, and in theory, there is no need for the backward, upward and right-sided pressure manoeuvre to view the glottis using the device. We propose the following reasons for the occasional failure of the paediatric GlideScope to expose the glottis and the need for the backward, upward and right-sided pressure manoeuvre for glottic exposure in paediatric patients. The view of the paediatric GlideScope (size 3, reusable blade) includes a 13-mm wide blind area just below the tip of the blade [3]. The camera's field of view does not cover the tangent of the distal half of the blade. The 13 mm-wide blind spot may require a more anterior direction of the camera view and the backward, upward and right-sided pressure manoeuvre in order to obtain a better exposure of the glottis. 

 

Anaesthetists performing laryngoscopy should pay attention to the fact that the paediatric GlideScope camera has a blind spot just below the tip of the blade, especially in patients with short necks, restricted neck movement or significant macroglossia.

 

Y Hirabayashi

Y Otsuka

 

Jichi Medical University

Tochigi, Japan

E-mail: yhira@jichi.ac.jp

Y. Hirabayasi received an honorarium from Verathon Medical Inc. for a lecture. No other person involved in this correspondence has any financial relationship with the GlideScope® video laryngoscope or any other equipment from other companies.

No external funding and no competing interests declared

References

1  Karsli C, Armstrong J, John J. A comparison between the GlideScope® Video Laryngoscope and direct laryngoscope in paediatric patients

　 with difficult airways – a pilot study. Anaesthesia 2010; 65: 353-7

2  Hirabayashi Y, Otsuka Y. Early clinical experience with GlideScope® video laryngoscope in 20 infants. Paediatric Anaesthesia 2009; 19: 802-4

3  Hirabayashi Y, Otsuka Y. Apparent blind spot with the GlideScope video laryngoscope. British Journal of Anaesthesia 2009; 103: 461-2