English

Abstract

BACKGROUND Failure in managing the airway is the most important cause of death in patients undergoing general anaesthesia (GA). For effectively preventing airway catastrophe it is essential to have a meticulous airway assessment pre-operatively. Many methods are in use to predict difficult airway like Mallampati, Wilson’s scoring, percentage of glottic opening (POGO) scoring, Cormack - Lehane classification, thyromental distance, mandibular hyoid distance, atlantooccipital joint extension etc. In this study, we compared between two popular methods of airway assessment, upper lip bite test (ULBT) and height to thyromental distance ratio (RHTMD) to predict the difficulty in tracheal intubation. METHODS This descriptive study was conducted at Government Medical college, Thrissur, over a period of one year , on 76 patients of American society of Anaesthesiologist (ASA) - PS l - lll, requiring general anaesthesia. ULBT and RHTMD were used to assess the patient’s airway. It was correlated with Cormack - Lehane classification during direct laryngoscopy. The data was analysed using Fisher exact test (P < 0.05) and Kappa statistics. RESULTS Out of the 76 patients, 41 (53.9%) were women 35 were men (46.1 %). ULBT predicted 89.6 % [25 + 43] belonging to class 1 and 2 as easy, while 10.5 % [8] of class 3 as difficult. RHTMD predicted 35 patients (46 %) as easy (grade 1) and 41 patients (54 %) as grade 2. Using ULBT, of the 8 patients predicted to have difficult intubation (Class 3), 2 were found practically difficult and 6 were easy. In remaining 68 patients, 23 patients had difficult view and 45 had easy view. According to Cormac and Lehane, among 41 patients who predicted difficult by RHTMD, 19 patients were practically difficult and 22 were easy. Of 35 patients, 6 patients were difficult and 29 were easy. CONCLUSIONS The RHTMD is more sensitive compared to ULBT in predicting difficult intubation. As assessed by Cormack - Lehane classification. KEYWORDS Difficult Intubation, Ratio of Height to Thyromental Distance, Upper Lip Bite Test