Reliability of Paramedic Ratings of Laryngoscopic Views during Endotracheal Intubation

Abstract

Background.Prior studies have related prehospital endotracheal intubation (ETI) difficulty to paramedic visualization of the vocal cords using the Cormack-Lehane (C-L) scale. However, the reliability of paramedic C-L ratings has not been formally studied.Objective.To evaluate the reliability of C-L anda more recently described scale, percentage of glottic opening (POGO), when used by paramedics to rate laryngoscopic views during ETI.Methods.Twenty-five standard slide images of laryngoscopic views were obtained during ETI. The 25 images were duplicated to facilitate evaluation of intrarater agreement (total 50 slides). Seven paramedics rated the degree of vocal cord visualization in each image using C-L (I–IV, ordinal scale; I = full visualization of vocal cords, IV = only epiglottis seen) andPOGO (0–100 continuous scale; 0 = no vocal cords seen, 100 = full visualization of vocal cords). We assessed intra- andinterrater reliabilities using Cohen's multirater kappa for C-L andintraclass correlation coefficients (ICCs) for POGO.Results.C-L showed variable intrarater reliability (kappa range = 0.37–0.90) andpoor interrater reliability (Cohen's multirater kappa = 0.22). POGO demonstrated good to excellent intrarater reliability (one-way random-effects ICC range = 0.57–0.87) andfair to good interrater reliability (two-way random-effects ICC = 0.59, 95% Confidence interval: 0.48–0.71).Conclusions.Paramedic C-L ratings exhibit poor intra- andinterrater reliabilities. Paramedic POGO ratings exhibit fair to good intra- andinterrater reliabilities. POGO may be more appropriate than C-L for prehospital clinical andscientific application. Reliability must be formally evaluated for any proposed laryngoscopic exposure classification system.

Keywords:

• laryngoscopy
• paramedics
• endotracheal intubation
• Cormack-Lehane scale
• percentage of glottic opening
• reliability