Author(s): Sivaraj P, K. R. Padmanaban

BACKGROUND Anaesthesiologists are confronted daily with the task of determining whether endotracheal intubation will be of increased difficulty in a patient. Several clinical tests were designed to predict difficult intubation. But none of the tests has provided satisfactory results in terms of sensitivity and specificity. A reasonable explanation is that the clinical tests are all physical examinations according to the surface markers, so the effect of bones may not be included. Lateral neck radiography may be regarded as an important predictor of difficult laryngoscopy. MATERIALS AND METHODS Two hundred and eight patients in the age group of 25-65 years of either sex were included in the study. We assessed the radiological variables: the atlanto-occipital distance, cervical vertebra C-2 spine depth, effective mandibular length, anterior mandibular depth, posterior mandibular depth in all the patients. Patients with tumours or malformations of head and neck and oral cavity, edentulous patients, pregnant patients and those requiring emergency surgeries were excluded. A Cormack-Lehane grade of I and II were considered as easy intubation and III and IV were considered as difficult intubation. RESULTS Thirty-eight patients had difficult intubation. The Atlanto-Occipital distance has sensitivity and specificity of 97.43% and 94.11%. The PPV and NPV is 78.72% and 99.37%. In Effective Mandibular Length, the sensitivity and specificity are 67.56% and 66.66%. The PPV and NPV is 30.48% and 90.47%. In Anterior Mandibular Depth, the sensitivity and specificity are 77.77% and 51.16%. The PPV and NPV is 25% and 91.66%. In Posterior Mandibular Depth the sensitivity and specificity are 43.24% and 52.04%. The PPV and NPV is 16.32% and 80.90%. In C2 Spine depth the sensitivity and specificity are 48.71% and 59.76%. The PPV and NPV is 21.83% and 83.47%. CONCLUSION From this study, we found that 1. Lateral neck radiography is useful but unable to provide good sensitivity in prediction of difficult intubation. 2. Only the atlanto-occipital distance variable has significant sensitivity and specificity as a single radiological predictor.