Comparative Study of Upper Lip Bite Test and Modified Mallampatti Classification in Predicting Difficult Endotracheal Intubation

Abstract

Objective: To compare sensitivity, specificity, positive and negative predictive values of upper lip bite test and modified mallampatti test to predict difficulty in endotracheal intubation in patients between 16 to 55 years of age. Methods: One hundred ASA1/2 patients admitted for elective surgical procedure requiring endotracheal intubation were prospectively studied to predict difficult intubation in age group 16-55 years of age after obtaining an informed consent. Preoperative Airway assessment was done with modified mallampatti test and upper lip bite test. Results: In our study, eighty four had Upper lip bite test (ULBT) class I and II and sixteen patients had class III. Of these two ofthe ULBT class Iand II and five of the ULBTclassIII had Cormack Lehane grade III . There were one hundred patients predicted to be easy for intubation by MMT (i.e. patients who had ULBT class I and II) out of whom however, we encountered difficult intubation in 6 patients. One in MMT class III also had difficult intubation. None of the patients had class IV MMT.Of the entire one hundred patients, a total of seven patients had difficult intubation, all of whom had Cormack Lehane class III on laryngoscopy. Conclusion: Upper Lip Bite Test (ULBT)is a better test at predicting difficult endotracheal intubation when compared toModified Mallampati Test (MMT). Upper lip bite test and modified mallampatti classification are good predictors of easy intubation rather than difficult intubation. Upper lip bite test should be used in combination with other airway assessment methods viz. Thyromental distance, hyomental distance, inter incisor distance to predict difficult intubation.