We read with interest the article by Teoh et al  comparing intubating characteristics of three different video laryngoscopes with those of the Macintosh laryngoscope.
Video laryngoscopy is becoming increasingly popular, especially to aid tracheal intubation in patients with difficult airways. Like Mines and Ahmad  we have concerns about the use of the Cormack and Lehane grading system during video laryngoscopy as a clinical information sharing tool.
When Cormack and Lehane originally designed their grading system more than two decades ago, their purpose was to encourage training and to aid decision making during direct laryngoscopy . Cormack has reinforced this issue in recent correspondence .
Since then the system has become widely used on anaesthetic charts to aid subsequent anaesthetists with decision making and planning. Although not designed as an information sharing tool, the Cormack and Lehane grading has served this purpose well for direct laryngoscopy. However, we feel it is not an appropriate tool for information sharing for videolaryngoscopy.
During direct laryngoscopy the larynx is viewed from outside the oral cavity. The distance between the object (vocal cords) and the viewer (laryngoscopist’s eye) and the angle of vision that is 15 to 30 degrees, contribute to the restricted view. During videolaryngoscopy, a camera or a viewing lens is situated near the tip of the laryngoscope blade, near to the larynx with an angle of view of 50 to 60 degrees. With these advantages, the view using videolaryngoscopy is almost certain to be better than with direct laryngoscopy. Many studies have demonstrated that videolaryngoscopy improves the view; however this does not always translate into easier tracheal intubation [5, 6].
Regarding research studies of videolaryngoscopy the intubation difficulty scale (IDS), proposed by Adnet et al  could be considered. It incorporates seven separate variables and captures indices of difficulty common to both direct and indirect laryngoscopes. It is, however, a complex scoring system and may not be so useful clinically as an information sharing tool.
Video laryngoscopes all vary slightly in design and function so developing a single robust scoring system may not be possible. Instead we recommend concise documentation to aid future anaesthetic management which should include: (i) name and size of the video laryngoscope, (ii) grade/experience of the laryngoscopist, (iii) number of attempts (iv) optimising position/use of adjuncts, (v) easy/difficult/failed intubation.
S. P. Angadi
University Hospitals of Leicester NHS Trust,
Northampton General Hospital NHS Trust,
No external funding and no competing interests declared.
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2. Mines R, Ahmad I, Teoh WHL, Shah MK, Sia ATH. Can you compare the views of videolaryngoscopes to the Macintosh laryngoscope? Anaesthesia 2011; 66: 315-7
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7. Adnet F, Borron SW, Racine SX, et al. The intubation difficulty scale (IDS): proposal and evaluation of a new score characterising the complexity of endotracheal intubation. Anesthesiology 1997; 87: 1290-7.
S Pradeep Angadi