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.[1] A modified version that subdivided Grade 2 was initially described in 1998.[2]
Grade | Description | Approximate frequency | Likelihood of difficult intubation |
---|---|---|---|
1 | Full view of glottis | 68-74% | <1% |
2a | Partial view of glottis | 21-24% | 4.3-13.4% |
2b | Only posterior extremity of glottis seen or only arytenoid cartilages | 3.3-6.5% | 65–67.4% |
3 | Only epiglottis seen, none of glottis seen | 1.2-1.6% | 80–87.5% |
4 | Neither glottis nor epiglottis seen | very rare | very likely |