Effect of supine and upright position on Mallampati grading in predicting difficult laryngoscopy and intubation: a prospective, observational study

Background: Mallampati grading (MPG) classification in a sitting position is the most commonly used method for airway assessment. The study aimed to compare the predictive value of MPG in the sitting and supine positions to predict difficult tracheal intubation (DTI). Patients and Methods: The present study was a prospective, blinded, and observational study. Three hundred nine patients aged 18–60 years, scheduled for surgery requiring orotracheal intubation, were included. Airway assessment was performed preoperatively, including sitting MPG with and without phonation. Supine MPG with and without phonation was noted in the operation theater. The ease of bag-mask ventilation (BMV) and laryngoscopy view were graded according to the Han scale and the Cormack and Lehane scores, respectively. A receiver operating characteristic curve was used to assess the cutoff point, sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV) of MPG, and body mass index for predicting DTI. Results: Difficult BMV, DTI, and both (difficult BMV and DTI) were observed in 22.7%, 12.9%, and 5.2% of patients, respectively. MPG in the sitting position without phonation yielded the highest diagnostic accuracy (76.38%), specificity (79.55%), and PPV (28.6%), with good sensitivity (55%) and NPV (92.2%). Supine MPG without phonation showed comparable results. Conclusion: Sitting position MPG without phonation is the best predictor of DTI, followed by supine MPG without phonation. Therefore, supine MPG without phonation is equivalent to sitting without phonation MPG and can be used for predicting DTI whenever the patient cannot be made upright.