Do the Head-elevated Position and the Use of a Videolaryngoscope Facilitate Orotracheal Intubation in a Patient Population Without Predictable Difficulty of Intubation

Airway management remains an important determinant of morbidity and mortality in anesthesia, despite progress in recognizing factors of difficult mask ventilation and intubation. Many recommendations have been published regarding the practice of intubation in anesthesia. Our study focuses on two topics which remain under discussion: the position of the patient's head and the use of a videolaryngoscope.

As to patient's head position, most anesthesiologists place the patient in the sniffing position (supine torso with neck flexed forward, and head extended), a position denominated "sniffing"by analogy to that adopted to smell a perfume. However, Adnet et al. questioned this position based on magnetic resonance imaging of eight healthy young volunteers positioned either with their heads in a neutral position or in extension, or with their heads and necks on a pillow. They showed that the sniffing position does not allow the alignment of the three important axes (mouth, pharynx and larynx) in awake patients with normal airway anatomy [1]. The "Head Elevated Laryngoscopic position" (HELP), with a raise of the head and neck so that "An imaginary horizontal line should connect the patient's sternal notch with the external auditory meatus" [2] facilitates the alignment of the pharyngeal, laryngeal, and oral axes of the airway during difficult laryngoscopy [3].

As to videolaryngoscopy, there is no doubt that it is a major advance in airway management. A recent Cochrane Systematic Review concluded that videolaryngoscopy increased easy laryngeal views and reduced difficult views and intubation difficulty [4]. However, its place is still debated: first line or rescue in case of suspected difficult airway. Its systematic use means discarding the standard Macintosh laryngoscope [5] which is not supported by clinical studies, in particular those of Wallace et al. [6] and of Thion et al. [7].

In the present randomized study we will study a combination of two factors in tracheal intubation on patients without suspected airways abnormalities: position (sniffing or HELP) and a McGrath laryngoscope (with or without video). This leads to four groups, A: sniffing position plus McGrath Mac videolaryngoscope with its screen deactivated so as to mimic a plain laryngoscope (R-V-), B: HELP plus McGrath Mac videolaryngoscope with a deactivated video screen (R+V-), C: sniffing position plus a McGrath Mac videolaryngoscope with an activated video screen (R-V+), D: HELP plus a McGrath Mac videolaryngoscope with it video screen activated (R+V+). This protocol allows using the same type of laryngoscope in all cases.