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 and a 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) and POGO (0-100 continuous scale; 0 = no vocal cords seen, 100 = full visualization of vocal cords). We assessed intra- and interrater reliabilities using Cohen's multirater kappa for C-L and intraclass correlation coefficients (ICCs) for POGO. RESULTS: C-L showed variable intrarater reliability (kappa range = 0.37-0.90) and poor 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) and fair 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- and interrater reliabilities. Paramedic POGO ratings exhibit fair to good intra- and interrater reliabilities. POGO may be more appropriate than C-L for prehospital clinical and scientific application. Reliability must be formally evaluated for any proposed laryngoscopic exposure classification system.
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 and a 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) and POGO (0-100 continuous scale; 0 = no vocal cords seen, 100 = full visualization of vocal cords). We assessed intra- and interrater reliabilities using Cohen's multirater kappa for C-L and intraclass correlation coefficients (ICCs) for POGO. RESULTS: C-L showed variable intrarater reliability (kappa range = 0.37-0.90) and poor 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) and fair 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- and interrater reliabilities. Paramedic POGO ratings exhibit fair to good intra- and interrater reliabilities. POGO may be more appropriate than C-L for prehospital clinical and scientific application. Reliability must be formally evaluated for any proposed laryngoscopic exposure classification system.
Authors: Joseph S Turner; Timothy J Ellender; Enola R Okonkwo; Tyler M Stepsis; Andrew C Stevens; Christopher S Eddy; Erik G Sembroski; Anthony J Perkins; Dylan D Cooper Journal: Intern Emerg Med Date: 2016-06-14 Impact factor: 3.397