Is there an optimal place to hold the endotracheal tube during direct laryngoscopy for patients undergoing surgery under general anesthesia? Protocol for a randomized controlled trial

BACKGROUND: Endotracheal intubation by direct laryngoscopy is a widely performed lifesaving technique. Although there are guidelines for optimal size and depth of insertion of an endotracheal tube (ETT) for successful intubation, there is no consensus on the point at which it should be held along its length. This will arguably affect the time, ease, and success of the technique due to a difference in visualization and torque applied to the ETT after glottic visualization. We aim to compare the effect of 2 different sites of holding the ETT on time to intubation (TTI), intubation difficulty scale (IDS), and complications. METHODS: ASA 1–2 patients (>18 years) posted for surgery under general anesthesia, undergoing supervised intubation by anesthesia trainees (experience < 18 months), will be included. Patients with an anticipated difficult airway or unanticipated difficulty—CL grade 3 or 4 requiring the use of airway adjuncts—will be excluded. Patients will be randomized by a computer-generated number list, and allocation concealed with opaque sealed envelopes. The two sites for holding the ETT will be group 1 at 19 cm and group 2 at 24 cm. ETT marked at the selected site will be handed by the technician once the optimum position of the table, patient, and laryngoscopic view is confirmed by the intubator. The entire procedure will be video recorded. Two blinded assessors will independently review the videos to document the time to intubation and intubation difficulty score. A postoperative sore throat will be recorded. SAMPLE SIZE: To detect a 20% difference in time to intubation between groups with a significance level of 5% and power of 85%, we will need a total of 298 patients. Accounting for data loss, we plan to recruit 180 patients in each group. DISCUSSION: This will be the first study to assess whether the site of holding the tube has any impact on the ease and time taken for intubation. The findings of this study will provide scientific evidence for suggesting an appropriate place for holding the ETT during direct laryngoscopy procedures. TRIAL REGISTRATION: Clinical Trials Registry India CTRI/2019/09/021201