A comparison of the Mallampati test in supine and upright positions with and without phonation in predicting difficult laryngoscopy and intubation: A prospective study

BACKGROUND AND AIMS: Difficult ventilation and intubation have been recognized as the forerunners of hypoxic brain damage during anesthesia. To overcome catastrophic events during anesthesia, an assessment of the airway before induction is of paramount importance. We designed this study to compare the effect of phonation on the Mallampati test in supine and upright positions as against the traditionally employed test without phonation in serving to predict difficult laryngoscopy and intubation. MATERIAL AND METHODS: In this cross-sectional study, 661 patients aged 16-60 years were recruited during the years 2011 to 2012. The Mallampati test was conducted on patients with and without phonation in both the sitting and supine positions. A blinded observer then performed laryngoscopy and intubation. Difficult intubation was assessed according to the Cormack-Lehane Grading scale. Statistical Analysis Used: Diagnostic statistical measures for each of the four situations — sensitivity, specificity, positive and negative predictive values and accuracy — were calculated. RESULTS: In this study, 28 patients (4.2%) had difficult laryngoscopy and nine patients (1.4%) had difficult intubation. There was no difference in the sensitivity of the Mallampati test as regards prediction of laryngoscopy and intubation in the four different positions, but the upright position along with phonation had the highest specificity. The negative predictive value was above 95% in all the positions; however, the positive predictive value was the highest in the supine position along with phonation. CONCLUSION: Based on our results, the supine position along with phonation had the best correlation in the prediction of difficult laryngoscopy and intubation. We further conclude that phonation significantly improved the Mallampati class in the supine position compared with the upright position.