Effects of direct laryngoscopy versus Glidescope videolaryngoscopy on subjective and objective measures of cognitive workload: an in-vivo randomized trial.

Background: Laryngoscopy and tracheal intubation are associated with high operators' workload, which potentially causes lower performance and risk of errors. Measuring anesthesiologists' mental workload during instrumental procedures allows to test the usability of the devices and, by managing operators' workload, improve clinical decision making. The aim of this study was to investigate the differences in subjective and objective cognitive workload between videolaryngoscopy with hyperangulated blade (Glidescope) vs. direct laryngoscopy in a real clinical setting.

Methods: Fourteen anesthesiologists were enrolled and performed three intubations for each device, a Glidescope videolaryngoscope (Verathon Inc., Schiltigheim, France) and a Macintosh (Apple Inc., Cupertino, CA, USA) direct laryngoscope, in a random order. The subjective workload was assessed with the NASA Task Load Index questionnaire right after intubation and reaction times to a secondary task were recorded during laryngoscopy and intubation as an objective measure of workload.

Results: The overall perceived workload (P<0.001) and the subscales of physical demand (P<0.001) and effort (P<0.001) were lower during Glidescope than during Macintosh laryngoscopy. Reaction times were faster during Glidescope than during Macintosh laryngoscopy (P<0.014). A significant positive correlation was found between reaction times and the overall perceived workload (P<0.001).

Conclusions: A videolaryngoscope with hyperangluated blade used in a real clinical scenario of elective surgery significantly reduced both subjective and objective workload compared to a direct laryngoscope. Physical demand and effort were the key components in reducing operators' mental workload. Therefore, the expert use of a videolaryngoscope with hyperangulated blade constitutes an ergonomic option that could limit operators' workload and improve patients' safety and operators' well-being.