School of Medicine

Background : A method to discern a trainee's expertise with direct laryngoscopy would be useful for following progress and determining readiness for call or advanced assignments. We have developed methodology to record laryngoscopy motion and performance. The goal of this study was to determine whether laryngoscopy skill could be evaluated by electronic assessment of technique. Methods : Three anesthesia faculty with three to 23 years experience performed laryngoscopy five times each on a Medical Plastics Intubation Mannequin. Blade path and force were measured with a Mini-Bird magnetic position sensor (Ascension) and a 6-axis force transducer (ATI), respectively, attached to the laryngoscope handle and recorded on a Dell laptop computer. A Matlab (Mathworks) program digitally aligned the separate laryngoscopy trajectories and a virtual curvilinear tube was calculated within the mannequin airway that encompassed all the expert trajectories. Twelve residents were studied on the first day of their anesthesia residency. They performed laryngoscopy three times on the same mannequin with the instrumented handle. The percentage of the trajectory that fell within the expert tube was measured for each laryngoscopy. Residents were divided into high and low experience groups, high being > 20 previous laryngoscopy attempts in an airway model, and into upper and lower 50th percentiles based on laryngoscopy success in their first 10 patient attempts. Trajectory percentages, force, torque, and jerks were compared between groups by T-test. Results : A trajectory from one expert generally fell within the tube derived from the other two experts. Resident laryngoscopies fell within the expert tube an average 74% ± 6% (mean ± SE) of the path length (P < 0.001 vs. 100%). Conformity to the expert path was greater in the upper third of the airway (93% ± 3%) than near the larynx (61% ± 10%, P < 0.01). Conformity did not appear to differ among residents as a function of previous experience or patient laryngoscop.