A Comparison of Two GlideScope Intubation Techniques

A Difficult intubation is still one of the most daunting challenges in anesthesiology. One of the tools used to assist with a difficult tracheal intubation is the GlideScope (GS) (Verathon, Bothell, WA, USA). The GS is a video laryngoscope that has a 60 degree angle blade with a built-in high-resolution camera and a light source assembled beside it. The image is transmitted onto a mobile bedside monitor. It has been widely used in medicine for over a decade. The GS was designed to provide an improved view of the glottis during difficult intubations without alignment of the oral, pharyngeal and tracheal axes, as it is able to "look around the corner" to facilitate the intubation.

The standard technique of the GS intubation involves a midline laryngoscopy followed by the insertion of a styleted endotracheal tube (ETT) once an adequate view of the vocal cords has been achieved. The ETT insertion process requires the operator to look away from the monitor during the laryngoscopy while maintaining the blade position in order to insert it into its initial position.

An alternative GS intubation technique has been described for cases in which there is limited mouth opening, a big tongue or other anatomical impediments. In these cases the ETT is inserted under direct vision as a "fish hook" at the side of the mouth before the GS blade is introduced into the oropharynx.

There are several advantages to this alternative technique. The first advantage is that this technique of ETT insertion would minimize the laryngoscopy time as a part of it is performed before the blade is introduced and the stimulating effect occurs. This technique thus has the potential of reducing the sympathetic response. Minimizing oropharyngo-laryngeal stimulation time would theoretically attenuate the hemodynamic response.

Inclusion criteria

• Patients of ASA physical status 1-2
• Patients aged 18 years and older
• Patients undergoing elective surgery that requires tracheal intubation

Exclusion criteria

• Patients in whom a rapid sequence intubation or alternative intubation method is indicated
• Patients with a known or suspected oral, pharyngeal or laryngeal mass
• Patients previously flagged as a difficult intubation
• Patients with hypertension (treated or untreated, poor dentition, symptomatic gastro-esophageal reflux or cervical spine instability