Abstract PR545

Abstract

Background & Objectives: Background:Data available is inconclusive to say that tracheal intubation is more difficult in the obese. Unanticipated difficult tracheal intubations (DTI) are probably the result of a lack of accurate predictive tests for difficult intubation. By adopting multiple airway assessment factors the deficiency occurring with individual factors can be avoided. Objectives: This study compares the incidence of DTI between obese and non obese patients using Intubation difficulty score(IDS) and compares three predictors of difficult intubation; Neck circumference to Thyromental distance ratio(NC/TM), Mallampati Score (MPC)and Wilson Score (WS). Materials & Methods: This prospective observational study conducted after approval by Institutional Review Board in a tertiary care center.250 patients, aged 18-60 yrs, ASA I&II were assigned to two groups;obese and non obese based on their BMI (Obese; BMI>30). Difficulty of intubation was assessed using the IDS (IDS>5). Predictors of DTI included MPC 3 or 4, WS≥ 2, and NC/TM≥5. Results: The incidence of DTI determined by IDS was more frequent in obese group (88.6%vs 11.4%;p<0.05). Among these three predictors, WS showed highest specificity and NPV, and a larger area under curve (AUC) but very low sensitivity (table 1).The ROC curves shows maximum AUC for WS (0.789) and MPC(0.723) indicating good predictors(figure1).However, Both WS and MPC had high false negative rate, which is not clinically acceptable as it increases the number of unanticipated difficult intubations.Conclusion: While this study clearly proved that difficult intubation was more common in the obese; neither of the three predictors, MPC, WS, and NC/TM proved to be ideal to predict difficult intubation in obese patients.An increase in the cut off value of NC/TM from 5 to 6 would perhaps reduce the number of false positives in the Indian population, considering the lower mean value of TM(6.79cm) in our study group.