Relevance of ratio of neck circumference to thyromental distance in predicting difficult intubation

Abstract

Background and Objectives: Airway assessment is the most important aspect of anaesthetic practice as a difficult intubation may be unanticipated. A study was done to know the relevance of ratio of neck circumference to thyromental distance in predicting difficult intubation in general Indian population coming for surgery. Materials and methods: 500 Patients with ASA PS I& II were enrolled in the study were preoperatively assessed for airway parameters such as Modified mallampati classification, thyromental distance, sternomental distance, neck circumference to thyromental distance ratio and Wilson score. Intra-operatively all patients were classified according to Cormack and Lehane laryngoscopic view. Results: The mean age, Weight, Height and BMI of patients in our study was 34.43 years, 61.07 kg,69.2cms and 21.2 respectively. In our study we had a total of 15 difficult intubation with all of them belonging to Cormack-Lehane grade III. In our study we noted that among 15 patients with CLIII/IV only 4 had a SMD≤15.75 cm. With that we noted a sensitivity, specificity, PPV and NPV of 26.7%,75.1%,3.2% and 97.1%. Among 15 patients with CLIII/IV only 2 of them had Wilson score of more than 3.