Randomized evaluation of the performance of single-use laryngoscopes in simulated easy and difficult intubation

Single-use laryngoscopes are becoming used more widely.

We compared six types of single-use laryngoscope with the standard Macintosh laryngoscope using the Laerdal SimMan patient simulator. Twenty anaesthetists attempted to intubate the simulator with standardized airway settings allowing a full view of the vocal cords ('easy intubation'). The airway settings were then changed so that only the posterior part of the glottis was visible ('difficult intubation') and the anaesthetists were asked to intubate the simulator again.

The time to intubate with the standard laryngoscope was less in both easy (P<0.05) and difficult (P<0.01) intubations. The performance of five laryngoscopes during easy intubation (P<0.01) and four during difficult intubation (P<0.001) was significantly worse than that of the Macintosh. There was a significant difference in Cormack and Lehane grading between the laryngoscopes tested in both easy (P<0.05) and difficult (P<0.05) intubation. The percentage of glottic opening visible (POGO score) also differed between laryngoscopes in both the easy (P<0.01) and difficult (P<0.001) groups. The highest POGO scores were obtained with the Macintosh laryngoscope. During the difficult intubation simulation, the reusable Macintosh laryngoscope needed less use of a bougie and had fewer failed intubations than the single-use laryngoscopes, but these differences did not reach statistical significance.

Of the laryngoscopes tested, the standard reusable Macintosh laryngoscope performed best. The Europa was the best single-use laryngoscope. Some single-use laryngoscopes tested were significantly inferior to the Macintosh. This raises concern over their use in clinical practice, particularly if intubation is difficult.