Comparing the Efficiency of Three Third-generation Supraglottic Airways as an Intubation Route

This outcome corresponds to the time required to intubate with endotracheal tube (ET) through the supra-glottic airway device. The timer will be started when the flexible fiberoptic intubation scope is inserted in the SGA, and will be stopped when the air cuff of the ET is inflated inside the trachea and carbon dioxide (CO2) is obtained. This outcome will be assessed by the either the performer or second person responsible for data collection.

This outcome is dichotomic and represents success of intubation through the SGA on the first attempt. An attempt will be defined as any lowering of the ET towards the glottis. Thus, any raise of the ET to its original position on the fiberoptic intubation scope will be considered as a failed attempt. Similarly, any removal of the fiberoptic scope from the SGA will be considered as a failed attempt, regardless of an attempt to lower the ET. This primary outcome is dichotomous and answers to the question: "Was the first attempt successful?"

Regardless of the number of attempts, this outcome will be considered positive if the ET penetrated the trachea, the air cuff was inflated and capnography is positive, sustained and with normal values. A failed intubation would be, for example, to leave the SGA in place for the whole surgery or to remove the SGA to complete the endotracheal intubation.

For example, the ET is lowered and does not enter the glottis, and is raised up again while the scope is removed from the SGA : "one" failed attempt will be noted. If the scope is entered in the SGA, no attempt to lower the ET and the scope is removed : "one" failed attempt will also be noted. However, if the scope is inserted in the SGA, the ET is lowered a first time and raised on the scope, and the ET is lowered a second time and raised again on the scope, "two" failed attempts will be considered.

The time for whole procedure corresponds to the sum of the time required for installation of the SGA device and the time required for intubation through the device.

An evaluation of the laryngeal view on the first attempt of fibroscopy will be evaluated by the attending anesthesiologist with the following scale :

• Grade 1 : whole vocal cords are seen, the epiglottis is not seen at all
• Grade 2 : larynx plus the posterior surface of epiglottis are seen
• Grade 3 : the anterior tip of the epiglottis is seen
• Grade 4 : the anterior tip of the epiglottis is seen and encroaching on the view of vocal cords obstructing <50% of view
• Grade 5 : the epiglottis is completely obstructing the SGA opening, no view is seen

The easiness of insertion and ventilation will be graded using the following scale, as proposed by Talaat and al. in his trial on Air-Q and Fastrach devices.

• Easy means obtaining an effective airway, defined as normal chest movement and a square wave capnograph trace, from the first attempt
• Moderate means obtaining an effective airway in the second or third attempt with some manipulation of the technique of insertion
• Difficult means failure to obtain an effective airway after three attempts

The easiness of intubation will be subjectively evaluated by the attending anesthesiologist using the following scale:

• Easy, meaning that railing the ET into the trachea was easy
• Moderate, meaning that railing the ET needed mild corrective manoeuvers and the procedure was mildly longer than expected
• Difficult, meaning that railing the ET was considerably longer than expected and that many corrective manœuvres were done, as removing and reinserting the fiberoptic scope.

The anesthesiologist will be asked to report a subjective evaluation of the removal of the SGA once the patient is intubated.

• Easy removal
• Moderate difficulty
• Hard
• Impossible

The research team will report any adverse events. For example, accidental extubation during the removal of the SGA, blood on the device when removed, desaturation under 90%. As previously mentioned, if the attending anesthesiologist wants to stop the protocol for different reasons, as unsatisfactory ventilation, the standardized manipulations will be stopped and the anesthesiologist will pursue airway management according to his preferences.