Modified Mallampati Test in Supine versus Sitting Position as a Predictor for Difficult Intubation – An Observational Study

Abstract

Abstract Background: The modified Mallampati test (MMT) is routinely employed to predict difficult laryngoscopy and tracheal intubation. This test, as a standard, when conducted with a patient in a sitting position, exhibits limited practicality due to its relatively low sensitivity and specificity in predicting difficult tracheal intubation (DTI). It is hypothesised that MMT, when performed with a patient lying supine, may improve its efficacy as a predictor of DTI. Methods: This single-centre prospective observational study was conducted involving 455 adult patients requiring general endotracheal anaesthesia. During preanaesthetic evaluation, MMT was performed in the sitting position as a standard (sitting MMT). Subsequently, independent observers recorded the MMT in the supine position (supine MMT) before administering general anaesthesia. The sitting and supine MMT were correlated with Cormack and Lehane grades using the Chi-square test. Diagnostic performance metrics, including the area under the receiver operating characteristic (ROC) curve, sensitivity, specificity, positive predictive values (PPV) and negative predictive values, were employed to assess the predictive capabilities of MMT in both positions. Results: Out of 455 patients, 72 (15.8%) experienced difficult intubation (defined as Cormack–Lehane Grade III and above). Both MMT in the sitting and supine positions demonstrated strong predictive capabilities for DTI, with areas under the ROC of 0.799 and 0.779, respectively. While sitting in the MMT position exhibited higher sensitivity (55.6% vs. 28.8%), supine MMT demonstrated a superior PPV (86.1% vs. 55.6%). Conclusion: MMT, when conducted with a patient in a supine position emerges as an alternative and a reliable predictor for predicting DTI.