Video Laryngoscopic Techniques Associated with Intubation Success in a Helicopter Emergency Medical Service System

Objectives. Video laryngoscopy (VL) is a technical adjunct to facilitate endotracheal intubation (ETI). VL also provides objective data for training and quality improvement, allowing evaluation of the technique and airway conditions during ETI. Previous studies of factors associated with ETI success or failure are limited by insufficient nomenclature, individual recall bias and self-report. We tested whether the covariates in prehospital VL recorded data were associated with ETI success. We also measured association between time and clinical variables. Methods. Retrospective review was conducted in a non-physician staffed helicopter emergency medical service system. ETI was typically performed using sedation and neuromuscular-blockade under protocolized orders. We obtained process and outcome variables from digitally recorded VL data. Patient characteristics data were also obtained from the emergency medical service record and linked to the VL recorded data. The primary outcome was to identify VL covariates associated with successful ETI attempts. Results. Among 304 VL recorded ETI attempts in 268 patients, ETI succeeded for 244 attempts and failed for 60 attempts (first-pass success rate, 82% and overall success rate, 94%). Laryngoscope blade tip usually moved from a shallow position in the oropharynx to the vallecula. In the multivariable logistic regression analysis, attempt time (p = 0.02; odds ratio [OR] 0.99), Cormack-Lehane view (p < 0.001; OR 0.23), bodily fluids obstructing the view (p = 0.01; OR 0.29), and VL equipment failure (p < 0.001; OR 0.14) were negatively associated with successful attempts. Bodily fluids obstructing the view (p < 0.001; hazard ratio [HR] 0.51), VL equipment failure (p = 0.003; HR 0.42), shallow placement of blade tip within 4 seconds (p < 0.001; HR 0.40), number of forward movements (p < 0.001; HR 0.84), trauma (p = 0.04; HR 0.65), and neurological diagnosis (p = 0.04; HR 0.60) were associated with longer ETI attempt time. Conclusions. Bodily fluids obstructing the view, equipment problems, higher Cormack-Lehane view, and longer ETI attempt time were negatively associated with successful ETI attempts. Initially shallow blade tip position may associate with longer ETI time. VL is useful for measuring and describing multiple factors of ETI and can provide valuable data.