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

INTERVENTION: ARM 1: Nasotracheal intubation with videolaryngoscope GlideScope Titanium 1. Participants receive Study Information Pack in advance at least 1 hour prior to enrolment (the patients are acute due to maxillofacial trauma/abscess). This pack contains description of interventions, summary of risks associated with videolaryngoscopy and detailed information about the study process, 2. Nasotracheal intubation using the GlideScope Titanium videolaryngoscope a) after standardized induction to general anaesthesia ‐ preoxygenation, 100% oxygen for 5 min, propofol 2mg/kg, sufentanil 0,15 mcg/kg, suxamethonium 1.5 mg/kg ‐ the GlideScope Titanium videolaryngoscope is inserted to the patient mouth in order to visualize the vocal cords. A soft tracheal tube is subsequently introduced into trachea and cuff of the tube is inflated with small amount of air to form a seal. Pressure inside the cuff is measured in order to achieve pressures 20‐22 cmH20. Tracheal tube is kept in place for the duration of surgery. b) time of device (Glidescope Titanium videolaryngoscope) ‐ the device is inserted after induction to general anaesthesia and removed after successful insertion of tracheal tube. c) the device is inserted by a doctor with Board Certification in Anaesthesia ‐ anaesthetist d) approximate duration of the videolaryngoscope in place is one minute e) features differing from the control/comparator videolaryngoscope ‐ different shape of the blade, different monitor for visualization of the vocal cords., CONDITION: maxillofacial trauma predicted difficult airway management surgery requiring nasotracheal intubation PRIMARY OUTCOME: Time to tracheal intubation (sec) ; timer starts at discontinuation of face‐mask ventilation and stops once successful insertion of endotracheal tube is confirmed by anaesthetist (first visible etCO2 tracking on the monitor). SECONDARY OUTCOME: Total number of attempts for tracheal intubation (n) ; Reported by study administrator(s) ‐ independent person present in the operating room during tracheal intubation ‐ to a study logbook Total success rate of tracheal intubation (%) ; Ability to achieve tracheal intubation within three attempts. ; Reported by study administrator(s) ‐ independent person present in the operating room during tracheal intubation ‐ to a study logbook. Maximum three attempts allowed. Visualisation of the vocal cords (1‐4 points) ; Modified Cormack and Lehane score (MCLS) used (Yentis and Lee, Anaesthesia 1998): 1 ‐ full view of glottis, 2a ‐ partial view of glottis, 2b ‐ only posterior extremity of glottis seen or only arytenoid cartilages, 3 ‐ only epiglottis seen, none of glottis seen, 4 ‐ neither glottis nor epiglottis seen. ; Reported by study administrator(s) ‐ independent person present in the operating room during tracheal intubation ‐ to a study logbook. The operator has maximum three attempts to visualize the vocal cords. During the attempts for tracheal intubation, the administrator follows the monitor and scores the MCLS. INCLUSION CRITERIA: 1. emergency procedures of maxillofacial and dental surgery requiring nasotracheal intubation 2. expected difficult airway management ‐ limited mouth opening (less than 2.5 cm), Mallampati score 3 or 4