Predicting difficult intubation: A comparison between upper lip bite test (ULBT) and Modified Mallampati test (MMT)

Abstract

No anaesthesiologist like to face scenario of unanticipated difficult intubation, as it may cost patients life. Many tests are there to predict difficult intubation, amongst those tests Modified Mallampati test [MMT] is a gold standard test. Upper lip bite test [ULBT] is an acceptable option for predicting difficult intubation. Our study aimed to compare both the tests to predict difficult intubation. Objectives: To analyse positive predictive value (PPV), negative predictive value (NPV), sensitivity, specificity and accuracy of ULBT and MMT. To compare the results of both the tests to predict difficult intubation. Aim: To ascertain whether ULBT can be incorporated in standard protocol of airway assessment along with other tests to increase predictive accuracy of difficult endotracheal intubation Materials and Methods: It was prospective randomised comparative observational study carried out at single centre. Three hundred patients of either sex, aged between 16-60 yrs scheduled for elective surgery under general anaesthesia with endotracheal intubation were enrolled in the study. Preoperative evaluation of airway was done with ULBT and MMT and findings were documented.MMT class III,IV and ULBT class III were considered as predictors of difficult intubation. On the day of the surgery after direct laryngoscopy laryngeal view was noted and was classified according to Cormack and Lehane classification. Patients with Cormack Lehane class III,IV considered as difficult to intubate. Cormack Lehane classification (C &L class) redings were compared with ULBT and MMT. Observations and Results: Demographic data and ASA grade was same for both the groups as participants were same. By comparing ULBT with Cormack and Lehane score we got 88.46% sensitivity, 92.74% specificity, 71.87% Positive predictive value (PPV), 97.45% ne gative predictive value (NPV) and 92% accuracy. For MMT we go t 19.23% sensitivity, 91.93% specificity, 33.33% PPV, 84.44% NPV a nd 79.33% accuracy. Thus results showed accuracy, sensi tivity, PPV and NPV of ULBT were superior than MMT while specificity of both the tests was similar. Conclusion: With higher level of sensitivity, PPV, NPV and accuracy ULBT is a better choice for predicting difficult airway than that of MMT. ULBT should be incorporated in standard airway assessment protocol along with other tests.

Evaluation of the reliability of the upper lip bite test and the modified mallampati test in predicting difficult intubation under direct laryngoscopy in apparently normal patients: a prospective observational clinical study

“…MMT: Patient was asked to sit up with his mouth open as much as possible and to stick out his tongue without making a sound. Oropharyngeal structures are visualized and classified with the help of a flashlight [ 8 – 10 ].…”

Predictive Value of Modified Mallampati Test and Upper Lip Bite Test Concerning Cormack and Lehane's Laryngoscopy Grading in the Anticipation of Difficult Intubation: A Cross-Sectional Study at a Tertiary Care Hospital, Bhubaneswar, India

“…Khan et al compared the ULBT and MMT and showed that the former was more accurate (88.7% versus 66.8%), while sensitivity, NPV, and PPV were similar in both tests [ 4 ]. A study conducted by Sinharay et al [ 21 ] observed that sensitivity (88.46%), PPV (71.87%), and NPV (97.45%) of ULBT were higher than MMT with similar specificity of both tests. Likewise, a study conducted by Ali et al [ 22 ] revealed that the sensitivity (87.5%), PPV (71.6%), and NPV (97.3%) of ULBT were higher than MMT with comparable sensitivity.…”