The Effect of Device (Video vs. Direct Laryngoscopy) and Experience (Junior vs. Senior) on Situation Awareness During Simulated Endotracheal Intubation

Research has shown that video laryngoscopy compared to direct laryngoscopy resulted in a lower mental and physical workload (Caldiroli et al., 2014) and improved body posture (Grundgeiger, Roewer, Grundgeiger, Hurtienne, & Happel, 2015). Following a classical cognitive resource theory approach, reduced workload when using a video laryngoscope may enable the anesthesiologist to spend more cognitive resources on perceiving and integrating information and therefore may result in improved situation awareness (Endsley, 1995). In addition, the more upright body posture when using a video laryngoscope (Grundgeiger et al., 2015) may also result in the perception of more environmental variables or easier perception of these variables. In the present study, junior (n = 26) and senior (n = 26) anesthesiologists induced general anesthesia in a simulated patient (high-fidelity patient simulator). Half of the anesthesiologists used a Macintosh blade for direct laryngoscopy and the other half used a C-MAC for video laryngoscopy. During the endotracheal intubation, we implemented several events into the scenario such as a phone call and a drop in patient heart rate within six seconds from 74 to 51 bpm. Immediately after the intubation was finished, the experimenter entered and guided the participant out of the simulation room. The participant completed a questionnaire including questions about non-clinical events (i.e., what was the phone call about) and clinical events (i.e., what was the heart rate of the patient). We intentionally designed the phase of endotracheal intubation to be rather challenging in order to avoid floor effects in our situation awareness assessment. Despite the challenging nature, the clinical authors of this paper and informal feedback of the participants indicated that such a situation is common. Based on the findings that video laryngoscopes reduce mental and physical workload and result in an upright posture, we expected that the group using a video laryngoscope would show better situation awareness than the group using a Macintosh blade. In addition, based on the literature (Endsley, 2006), we expected that senior anesthesiologists would show better situation awareness than junior anesthesiologist. In contrast to our expectations, we observed no effects of device or experience on situation awareness or subjective workload. There may be several reasons for this finding. First, in the hospital under study, the C-MAC is not used as the standard device for laryngoscopy and therefore participants might lack experience in using the device. Second, our situation awareness measure may not have been sensitive enough because it was only based on a single measurement (cf. Wright, Taekman, & Endsley, 2004) and included only a limited number of questions. Third, the benefits in relation to workload (Caldiroli et al., 2014) and posture (Grundgeiger et al., 2015) may have smaller effects on situation awareness than we could have detected with our sample size. To test whether the presented scenario was too demanding to notice changes in the environment and build situation awareness, we ran the scenario with an additional three participants in each group (total n = 12) but did not include any non-clinical events. The workload scores indicated that the laryngoscopy without distractions was still perceived as similarly demanding to the laryngoscopy with the non-clinical and potentially distracting events. The present study did not provide evidence for improved situation awareness during endotracheal intubation when using a video laryngoscope compared to a direct laryngoscope. Furthermore, considering the additional data, it appears that during the brief phase from insertion until the removal of the blade, anesthesiologists do not have the capacity to also perceive relevant elements in the environment. Weinger et al. (2000) concluded that “during high workload airway procedures (e.g., awake fiberoptic intubation), it may sometimes be advantageous to have extra anesthesia personnel available to help. ” (p. 281). Considering the present results, one may question whether there are any low workload airway procedures at all.