PREDICTION OF DIFFICULT INTUBATION BY USING UPPER LIP BITE, THYROMENTAL DISTANCE AND MALLAMPATI SCORE IN COMPARISON TO CORMACK AND LEHANE CLASSIFICATION SYSTEM

Abstract

The aim: To evaluate efficacy of Modified Mallampati test (MMT), upper lip bite test (ULBT) and Thyromental distance (TMD) or combination of two method Modified Mallampati test (MMT)+ upper lip bite test (ULBT), Thyromental distance (TMD) + upper lip bite test (ULBT) in prediction of difficult intubation in patients undergoing GA. Materials and methods: Three tests were carried out in all patients by a single anesthesiologist. These were MMT, ULBT and TMD. Laryngoscopy was performed with patient’s head in the sniffing position. The laryngoscopy view was graded according to modified Cormack and Lehane classification system. Study was prospective, single cross sectional, in 151 adult patients who required GA with endotracheal intubation for elective surgery. On arrival in the operating room, routine monitoring and venous cannula were introduced. Midazolam, Fentanyl. and rocuronium, ketamine , propofol were given to facilitate endotracheal intubation. Results: Out of 150 assessed patients, 18 (12%) had difficult intubation. Of those 18 patients, 17 (83.33%) patients had Cormack and Lehane classification III and one patient (16.67%) had classification IV. Compared with Cormack and Lehane classification system as the gold standard for difficult intubation, the sensitivity and specificity of MMT was 66.67% and 96.97% respectively, while ULBT had a sensitivity of 77.78% and a specificity of 93.18%, and TMD had a sensitivity of 55.56% and specificity of 94.97% respectively. A combination of different tests improved their efficiencies. The sensitivity and specificity MMT and TMD combinations was 77.78% and 92.42% respectively, while it was 88.89% and 93.18%, respectively for MMT and ULPT. The combination of TMD and ULBT has a sensitivity of 88.33% and a specificity of 91.67%. Conclusions: Upper lip biting test has the best sensitivity while MMT had the best specificity. No single test alone can be reliable for predicting of difficult intubation. The combination of ULBT and MMT was the best in terms of both sensitivity and specificity for prediction of difficult intubation.