Learning curves of the Glidescope, the McGrath and the Airtraq laryngoscopes: a manikin study

Several video and optical laryngoscopes have been developed but few have been compared in terms of their learning curves and efficacy. Using a manikin with normal airways we compared the Glidescope, the McGrath, the Airtraq and the Macintosh laryngoscopes.

Sixty anaesthetists (20 staff, 20 residents and 20 nurses) participated in the study. All subjects were novice with the new devices. They intubated a Laerdal SimMan manikin (with normal airway) five times in a row with all laryngoscopes. The sequence of use of the devices was randomized. Before using a device, a presentation and a demonstration were provided. Outcome measures were: duration of intubation attempt, modified Cormack grades, dental trauma and difficulty of use.

The Airtraq had the most favourable learning curve and mirrored the Macintosh after two intubation attempts. The Glidescope and McGrath had steep learning curves but, after five attempts, differences persisted when compared with the Macintosh and Airtraq. Time taken to visualize the glottis was similar but time taken to position the endotracheal tube was shorter for the Airtraq when compared with the Glidescope and McGrath. Indirect laryngoscopes seemed to have advantages over the Macintosh blade in terms of laryngeal exposure and potential dental trauma.

In a 'normal airway' model, intubation skills with the new devices appeared to be rapidly mastered. The three indirect laryngoscopes provided a better glottic exposure than the Macintosh. The Airtraq displayed the most favourable learning curve, probably reflecting differences in the techniques of endotracheal tube placement: guiding channel versus steering technique.