Non-inferiority Trial Comparing visionPRO to Glidescope Video Laryngoscopes

This trial is a single-centre, pilot, patient-blinded, randomized controlled non-inferiority trial.

Patients who decide to participate in this study will have their surgery and follow up care proceed according to standard of care. Video laryngoscopy is standard of care for this patient population at LHSC. Once eligibility is confirmed and informed, written consent has been obtained, participants be randomized to one of two study groups:

• Laryngoscopy performed using the Glidescope device (Verathon Inc., Bothell, USA)
• Laryngoscopy performed using the visionPRO device (HEINE® Optotechnick, Gilching, Germany)

Surgery, anesthetic management, and intubation protocol will proceed according to standard of care.

(A) All patients are observed for ECG, oxygen saturation (SpO2), and non-invasive blood pressure. Pre-oxygenation is carried out by the provider based on patient characteristics and standard clinical procedures (EtO2 > 80%).

(B) After adequate pre-oxygenation, anaesthesia is initiated using a combination of fentanyl (0.1 - 0.15 µg.kg-1) / sufentanil (0.2 - 0.5 µg.kg-1), and propofol (2 - 3 mg.kg-1), with the choice of drugs and dosages tailored to the specific needs of the patient. Maintenance is achieved either through propofol infusion (TIVA) or inhaled anaesthetics. The selection of a neuromuscular blocking agent is based on the surgery's duration, the need for perioperative neurological monitoring, and the absence of allergies and organ failures. The agents and their dosages used are:

• Rocuronium (0.5 - 1.2 mg.kg-1); and
• Succinylcholine (1 - 2 mg.kg-1).

The train-of-four (TOF) method is employed by the study nurse for continuous quantitative monitoring of neuromuscular transmission. Complete muscle relaxation is confirmed by the absence of tactile and measured twitches in response to maximal TOF stimulation of the ulnar nerve at the adductor pollicis. Study personnel were instructed on the importance of achieving adequate neuromuscular blockade.

(C) The laryngoscopy attempt starts with a TOF count of 0/4, using the device specified by randomization:

• visionPRO (HEINE® Optotechnick, Gilching, Germany) or
• GlideScope (Verathon Inc., Bothell, USA)

The provider aims to achieve the clearest view of the laryngeal structures. External laryngeal manipulations (ELM) may be employed to enhance the view of the glottis, aiming for a Cormack and Lehane grade I or II. The endotracheal tube size and blade size are chosen according to the hospital's standard operating procedures (blade size: #3 for average patients, #4 for taller patients; standard ET sizes: 7.0-7.5 ID for female patients and 7.5-8.0 ID for male patients). The method of glottic visualization and the size of the ET and blade are documented in the case report form (CRF).

(D) An intubation attempt is defined as the insertion and removal of the laryngoscope blade from the mouth, regardless of ET insertion success. A laryngoscopy attempt is considered successful if the tracheal tube is placed with a single blade insertion within 120 seconds and without manipulation of the laryngoscope by another provider. The following times periods until final ET placement are measured by a study nurse via a timer:

• "Time to intubation": duration from the opening of the patient's mouth to the passage of the ET through the vocal cords.
• "Time to view": the time from device insertion to visualization of the glottis;
• "Time to ventilation": the time from device insertion into the mouth until confirmation of the first CO2 wave on the anaesthesia respirator.

If the first attempt fails, the provider makes a second attempt with the same device, with mask ventilation recommended between attempts. A maximum of two laryngoscopy attempts are allowed. After two attempts the clinician switches to a preferred technique and records the direct and/or screen view. If this preferred technique fails after two attempts, the clinician proceeds with a preferred rescue technique. The study protocol recommends this limit of two intubation attempts and alternative technique selection in line with clinical standards. If ELM techniques, such as BURP (specific pressure applied to the cricoid cartilage), are needed during laryngoscopy, they are documented in the CRF. Throughout the induction of anaesthesia, a study nurse not involved in patient care records the study parameters.

24 hours following surgery, the patient will be assessed for presence and severity of sore throat rated on a scale of 0-3 (0 meaning no sore throat and 3 meaning severe sore throat), hoarseness rated on a scale of 0-3 (0 meaning no complaint and 3 meaning severe hoarseness), and cough rated on a scale of 0-3 (0 meaning no cough and 3 meaning severe cough).

Inclusion criteria

• Having elective surgery with general anesthesia
• At least 18 years of age
• requiring mechanical ventilation via an oral endotracheal tube

Exclusion criteria

• More than one predictor of an anticipated difficult airway (eg, body mass index (BMI) >40 kg/m2, unanticipated difficult airway in the medical history (eg, Cormack & Lehane (C&L) ≥III), reduction of the atlanto-occipital joint extension <35°, reduced thyromental distance <6 cm or Mallampati class ≥III)
• Age <18 years
• ASA class IV-VI
• Pregnant or breastfeeding
• Unable to provide informed written consent or under guardianship
• Urgent surgical intervention
• At high risk for aspiration
• Patients undergoing any neck and throat surgery.