Inverse intubation in entrapped trauma casualties: a simulator based, randomised cross-over comparison of direct, indirect and video laryngoscopy.

Background: Airway management in entrapped casualties with restricted access to the head is challenging. If tracheal intubation is required and conventional laryngoscopy is not possible, intubation must be attempted in a face-to-face approach. Traditionally, this is performed with a standard laryngoscope held in the right hand with the blade facing upward. Recently, alternative methods have been developed to facilitate difficult intubations, and we hypothesised that such techniques are also useful for face-to-face intubations.

Methods: 24 (trainee) anaesthesiologists attempted tracheal intubation in a patient simulator (SimMan, Laerdal, Norway) using three techniques in random order: (1) direct laryngoscopy (Macintosh blade #3), (2) indirect optical laryngoscopy (Airtraq, Prodol, Spain) and (3) video laryngoscopy (McGrath, Aircraft Medical, UK). The manikin was sitting with the neck immobilised and only accessible from the left anterolateral side. Success rate (percentage (95% CI)) and tube insertion time (median (IQR)) were recorded.

Results: Success rate did not differ significantly (Airtraq and McGrath 100% (84% to 100%), direct laryngoscopy 88% (68% to 96%)). Intubation was faster with Airtraq (25 s (22-34), p<0.001) and direct laryngoscopy (34 s (22-48), p<0.05) compared with the McGrath technique (55 s (37-96)).

Conclusions: All three techniques have a high success rate, but the usefulness of the video laryngoscope is limited due to longer intubation duration. Inverse direct laryngoscopy showed reasonable intubation times and, given the widespread availability of Macintosh laryngoscopes, seems a useful technique. Intubation was always successful and tended to be fastest with the Airtraq device, suggesting that this technique may be a promising alternative.