Low Skill Fibreoptic Intubation I-gel vs Air-Q

Tracheal intubation under general anaesthesia is the gold standard for securing the airway and for protecting the lungs against gastric aspiration. The conventional technique involves the use of a metal laryngoscope inserted into the mouth to create an air space, to allow insertion of an endotracheal tube.

Alternatively, an oral airway device (called a supraglottic device (SGD)) can be used for tracheal intubation. The SGD is first inserted. A fibrescope is inserted down the shaft of the SGD and into the trachea. This allows an endotracheal tube (previously pre-loaded onto the fibrescope) to be railroaded of the fibrescope and into the trachea. This technique is called 'low skill fibreoptic intubation' as the SGD acts as a guide for the fibrescope. Our study compares the performance of two SGD: i-gel and air-Q. The investigators will compare intubation success rate, insertion rate, and times for SGD insertion and intubation.

The investigators are testing to see if fibreoptic intubation in patients via a supraglottic airway device i.e. 'low skill fibreoptic intubation' (LSFOI) is more successful via the i-gel® than in the air-Q®. Patients are those scheduled for elective surgery under general anaesthesia who would normally require tracheal intubation. The investigator's hypothesis is based on the results of the investigator's recent manikin study (CIRB 2014/2039). The investigators would like to see if this hypothesis translates to patients. It will also test secondary outcomes e.g. SGD insertion success rates and times, and intubation times. In the aforementioned manikin study, the air-Q® performed better with the SGD insertion rates and times. However, the i-gel® performed better with intubation success rates and times. The devices may perform different due to differences between the devices: design (shape, volume, length, aperture), material composition, and technique required for insertion and intubation.

24 adult patients undergoing elective surgery requiring general anaesthesia and endotracheal intubation in the major operating theater of Singapore General Hospital will be enrolled. The patient will then be randomised in equal proportions into two groups, either the air-Q® or i-gel®. Patients will undergo induction of general anaesthesia in a standardised fashion and in accordance with usual practice in the investigator's department of anaesthesia. Intubation will then proceed with the assigned airway device. Data collected will include successful endotracheal intubation, as evidenced by the presence of end tidal carbon dioxide on a capnograph. Time to intubation (from the initial handling of the airway device until successful intubation is confirmed with successful lung ventilation), the number of attempts required and the view achieved (according to the modified Cormack and Lehane scoring system) will also be recorded. Injuries to the lips, teeth or upper airway will be sought and documented by a blinded observer in the Post Anesthetic Care Unit.

A protocol will be provided to standardise the induction of general anaesthesia. This will involve the application of standard patient monitors, a period of pre-oxygenation, and administration of anaesthetic agents and muscle relaxants. If the patient desaturates to SpO2 \< 94% during intubation, the intubation attempt via either the air-Q® or i-gel® will be abandoned and intubation will proceed using the conventional direct laryngoscope.

Eligibility Criteria:
Inclusion Criteria:

* Patients with a physical status of American Society of Anesthesiologists (ASA) grade I/II and over 21 years old, having elective surgery, who require endotracheal intubation

Exclusion Criteria:

* ASA class III/IV
* Patients with history of previous difficult endotracheal intubation
* Patients with two or more predictors of difficult airway management (criteria 1-8, below)

  1. Airway masses
  2. Mallampati (oropharygneal space grading) III or IV
  3. Thyromental distance \< 6.5cm
  4. Inter-incisor distance \< 3 cm
  5. Head extension \< 30 degrees
  6. Edentulous
  7. Large beard
  8. Obstructive sleep apnoea (OSA) or snorer
* Patients needing a rapid sequence induction
* Pregnant women