Accuracy of the upper lip bite test; modified Mallampati classification in predicting difficult endotracheal intubation

ABSTRACT

To compare the accuracy of Upper lip bite test with modified Mallampati classification for predicting the difficult laryngoscopic intubation. Cross sectional Study. The study was carried out at Department of Anaesthesiology, Intensive Care and Pain management, Combined Military hospital, Rawalpindi from September 2008 to August 2009. Four hundred patients undergoing elective surgery meeting the inclusion/exclusion criteria were enrolled after written informed consent. The airways of the patients were evaluated by using the modified Mallampati classification [MMP] and the Upper lip bite test [ULBT]. MMP class 3 or 4 and ULBT class 3 were considered as indicators of difficult intubation. The laryngeal view was graded by Cormack and Lehane classification [Gold standard]. Grade 1 or 2 was considered to represent easy intubation and grade 3 or 4 to represent difficult intubation. Sensitivity, specificity, positive predictive value, negative predictive value and diagnostic accuracy were calculated for both the tests separately by using the 2x2 table. ULBT had a higher accuracy of 94%, specificity of 99.2% and positive predictive value 70% compared to MMP accuracy of 82.7%, specificity of 84.4% and positive predictive value of 22.7%. The diagnostic accuracy of the Upper lip bite test was more than the modified Mallampati classification. We suggest that it be compared with the other prevailing tests as well which are often used to assess difficult intubations