Comparison of McGrath Series 5 video laryngoscope with Macintosh laryngoscope: A randomised, controlled trial in patients with normal airways

INTERVENTION: We recruited 100 patients of ASA physical status 1‐2 who were scheduled for elective surgery under general anaesthesia requiring tracheal intubation. After obtaining written informed consent, patients were assigned, by using a computer‐generated block randomisation, to laryngoscopy with either McGrath videolaryngoscope or the Macintosh laryngoscope. All tracheal intubations with both the Macintosh laryngoscope and McGrath videolaryngoscope were performed by one anesthesiologist who had used both devices more than 50 times clinically. All patients were expected to fast 6‐8 hours before surgery, and no one premedicated. With the patient placed in the supine position, routine monitors (consisting of a pulse oximeter, 3‐lead ECG and a non‐invasive blood pressure cuff) were applied. Baseline measurements were obtained and 3 min of pre‐oxygenation was performed before the induction of general anaesthesia. Standardised anesthetic induction was preformed with 1 mcg/kg fentanyl, 1‐2 mg/kg of propofol, and when consciousness was lost, 0.6 mg/kg of rocuronium was injected. After, making sure that all four TOF responses of the Adductor Pollicis disappeared, which ensures sufficient musclular blockade, intubation was then performed. Number 3 or 4 blades was used in all patients. A size 7.0 mm tracheal tube was used to intubate the trachea in female patients, and a size 7.5 mm tube was used for all male patients. If more than one intubation attempt was required, the patient received bag‐and mask ventilation between attempts and various manoeuvres were employed, including external laryngeal pressure, readjustment of the stylet and use of a bougie. Failed intubation was defined as failure after three attempts and a pre‐determined alternative airway management plan was instituted by the treating anaesthetist. Correct placement of the tracheal tube was confirmed by capnography and bilateral chest auscultation. Data were collected by one independent observer. The time taken for successful tracheal intubation was measured from the time the allocated laryngoscope was inserted in the patient’s mouth until end‐tidal carbon dioxide was detected. The difference between The McGrath videolaryngoscope with the Macintosh laryngoscope is to obtain laryngoscopic view with the help of a monitor. CONDITION: Tracheal intubation to patients with normal airways. PRIMARY OUTCOME: The primary outcome was the laryngoscopy view using percentage of glottic opening (POGO) score (0 to 100%, 100 = full view of glottis from anterior commissure to the inter‐arytenoid notch, 0 = even inter‐arytenoid notch is not seen). SECONDARY OUTCOME: Any complications associated with oro‐tracheal intubation, such as, , injury to lips, oral mucosal or dentition, oesophageal intubation, or hypoxia (SpO2 < 90%). Comparison of the laryngoscopy view using the Cormack and Lehane ; grading system (Grade I to IV). This is assessed by the anaesthetist performing the intubation, the view is seen during intubation. Haemodynamic changes (blood pressure, heart rate) during intubation. This is assessed by the independent observer, using the patient vital record on the monitor ( blood pressure measured by automatic sphygmomanometer, heart rate measured by ECG) Number of attempts needed for successful intubation Time for successful intubation or until alternative management selected. Alternative management will be decided after failed attempt with the allocated device. Failed attempt is defined as more than three intubation attempts. INCLUSION CRITERIA: Scheduled for elective surgery under general anaesthesia requiring tracheal intubation. Airway difficulty score (ADS) under 8 points. Amarican Society of Anesthesiology (ASA) physical status I‐II. Over 18 years of age.