Comparison of C-MAC D-blade video laryngoscope with C-MAC and Macintosh laryngoscope: A randomised, controlled trial in patients with normal airways

We recruited 180 patients of ASA physical status 1-3 who were scheduled for elective surgery under general anaesthesia requiring endotracheal intubation. After obtaining written informed consent, patients were assigned, by using a computer-generated randomisation code, to laryngoscopy with either C-MAC D-blade, C-MAC with Macintosh blade or Macintosh laryngoscope. All tracheal intubations were performed by anesthesiologists who had used all the devices more than 60 times in practice. Standard monitoring devices were attached before induction of anaesthesia (pulse oximeter, 3-lead ECG and a non-invasive blood pressure cuff). After the pre-oxygenation with 100% oxygen in order to achieve end-tidal oxygen >80%,anesthesia was induced with intravenous sufentanil 0.2-0.3 µg.kg-1 and propofol 2-3 mg.kg-1. Rocuronium 0.6-0.9 mg.kg-1 was administered for neuromuscular blockade after confirmation of successful manual bag-mask ventilation with patients placed in „sniffing“ head position. 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. Failure of the procedure was declared if intubation was not achieved within 120s, if more than three intubation attempts were required or if oxygen saturation dropped below 95%.. Intubation attempt was defined as commencing with placement of the device past the level of upper incisors (or upper lip if patient had no teeth) and similarly ending with removal of the device past the level of upper incisors(or upper lip if patient had no teeth). The failed attempt was subsequently managed at the discretion of the attending anaesthesiologist and the chosen technique was recorded. Correct placement of the tracheal tube was confirmed by capnography and bilateral chest auscultation. Data were collected by one independent observer.