A Randomized Controlled Trial to Compare the First-pass Intubation Success of the Airtraq Laryngoscope Versus the Macintosh Direct Laryngoscope in Patients Requiring General Anaesthesia for Elective Operation.

In recent decades, numerous videolaryngoscopes have been introduced to facilitate tracheal intubation. However, it remains unclear whether videolaryngoscope will increase the successful tracheal intubation compared with usual Macintosch laryngoscope. In a quantitative review on the performance of several non-standard laryngoscopes (e.g. Bonfils, CTrach, Glidescope), no strong evidence has been identified to support these devices to supersede the Macintosh laryngoscope. Owing to the lacks of randomized trials at the time, Airtraq has not been reviewed in the analysis.

The Airtraq laryngoscope is one of the optical indirect laryngoscopes, which provides glottis display without any deviation in the normal position of the oral, pharyngeal or the tracheal axes. Unlike other videolaryngoscopes, the Airtraq larygoscope is a non-steering novel airway device which has a guide channel for tracheal tube alongside with the blade. Its use has been showed to improve the ease of intubation in difficult airway situations. Up to date, randomized controlled trials comparing the Airtraq and Macintosh direct laryngoscopes are either small scaled or focusing on specific populations. And instead of the first-attempt success rate, the primary endpoints adopted have focused on the glottic view, intubation time, and cervical spine movement. The Difficult Airway Society has highlighted the importance of a robust and high standard of evidence to assess the use of new devices in airway management. Knowing that failed tracheal intubation has remained a major contribution to anesthetic-related morbidity and mortality, clinical relevant endpoint is essential to guide the selection of airway devices for tracheal intubation. Considering reports on unsuccessful tracheal intubation under satisfactory video-laryngoscopic view, using laryngoscopic view as a surrogate measure for successful intubation can give false assurances of device efficacy. While improvement in first-pass laryngoscopic success confers less airway trauma and possibly the prevention in deterioration to a 'Cannot Intubate Cannot Ventilate' scenario, it then translates into much more success than the improvement with multiple attempts and shortened intubation time. Meta-analyses have demonstrated that the Airtraq significantly decreased intubation time both in novice and in experienced anaesthetists compared with the Macintosh laryngoscope. Whereas in the first-attempt intubation, an increase in the first-pass success rate was only found in novice anaesthetists with significant analysis heterogeneity.

In view of these, a large pragmatic effectiveness trial using first-pass intubation success as the primary endpoint to compare the Airtraq and Macinotosh direct laryngoscope is necessary. The trial population should include normal and abnormal airways, a variety of elective and non-elective patients and proceduralists with mixed experience to allow results to be generalizable. A large trial would allow testing of subgroup effects that has not been previously possible and results would be generalizable due to its pragmatic design. The results of this trial will provide improved guidance for current airway algorithms.