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 |
