A comparison of videolaryngoscopes GlideScope and KingVision for nasotracheal intubation in maxillofacial patients with predicted difficult airway

Background: Videolaryngoscopy (VL) may improve intubation conditions in majority of patients, where the classical Macintosh laryngoscopy would be difficult or even may fail. Newer videolaryngoscopes posses smaller screens, they are also more portable and could be used outside the operating room. Modern videolaryngoscopes are also designed for visualization of the vocal cords in patients with limited mouth opening because of more slim shape of the blade. VL GlideScope Titanium is non-channeled videolaryngoscope with a slim reusable titanium blade and attached monitor while the VL KingVision is a portable device that can use a special single-use slim plastic blade theoretically useful in difficult nasotracheal intubation. Design: A randomized, interventional, single-blinded trial Objective: To evaluate in emergency patients scheduled for maxillofacial or dental surgery under general anaesthesia and requiring nasotracheal intubation whether the application of different videolaryngoscopes in the operating room has a different time to the successful placement of endotracheal tube through a nasal route. Primary outcome: time to successful intubation (sec) Secondary outcomes: total number of attempts, total success rate, visualization of the larynx. Methodology and sample size calculation: The average time intubation using GlideScope VL was reported as 49 (SD +/- 9) sec. Statistically significant difference was set as 5 sec (10%) - sample size was calculated using freeware: http://powerandsamplesize.com, with a power of 80% and type I error of 5%, Minimum number of patients in one group was calculated as 51. Including patients who do not complete the study for various reasons we decided to enrol total number of 110 patients (55 per group).