Assessment of the effect of supine posture and phonation on modified mallampati grading and its applicability in prediction of difficult airway

Abstract

Introduction: As it is not always possible to do Modified Mallampati Test (MMT) in sitting position, this study was designed to test the effect of supine position and phonation on classical MMT and use of such effect in predicting difficult laryngoscopical view or difficult intubation. Aim: To know the effect of phonation and supine position on classical MMT grade and to establish usefulness of modification in predicting difficult laryngoscopy or intubation. Objectives: 1. To compare classical MMT grades with those obtained in supine position with or without phonation. 2. To correlate MMT gradings obtained in all the three variations with Modified Cormack Lehane (MCML) grading and actual difficult intubations to obtain their powers in predicting difficult laryngoscopic view and difficult intubations. Material and Methods: A prospective observational study, conducted at a tertiary care hospital.Consenting, 130 adults, undergoing elective surgical procedures were included. MMT score in sitting position, in supine position with or without phonation was recorded in the preoperative area and MCML grading and actual difficulty for intubation were noted at the time of intubation. Emergency cases and patients with altered airway were excluded.Statistics: 'Kappa' agreement analysis was done to compare the agreement between various scores. Sensitivity, specificity, positive predictive value and negative predictive values were calculated. Results: Supine posture without phonation worsens the classical Mallampati grading whereas supine posture with phonation improves it. MMT in sitting and in supine position without phonation have very good agreement with each other in predicting difficult laryngoscopy and intubation. Conclusions: When the patient cannot sit for examination, MMT scoring can be done in supine position without phonation. Mallampati score in supine position with phonation is not recommended due to high false negatives.

Keywords

• Airway assessment in supine position
• Cormack–Lehane grading
• difficult airway
• Effect of posture and phonation on Mallampati grading