Cormack-Lehane classification system


The Cormack-Lehane system classifies views obtained by direct laryngoscopy based on the structures seen. It was initially described by R.S. Cormack and J. Lehane in 1984 as a way of simulating potential scenarios that trainee anaesthetists might face. A modified version that subdivided Grade 2 was initially described in 1998.
GradeDescriptionApproximate frequencyLikelihood of difficult intubation
1Full view of glottis68-74%<1%
2aPartial view of glottis21-24%4.3-13.4%
2bOnly posterior extremity of glottis seen or only arytenoid cartilages3.3-6.5%65-67.4%
3Only epiglottis seen, none of glottis seen1.2-1.6%80-87.5%
4Neither glottis nor epiglottis seenvery rarevery likely