Background: The MMC has been found to be of limited value and cannot be relied on for using in predicting difficult airway. Thus, we used a combination of multiple tests (combining MMC with Thyromental distance, Anatomical abnormality and Cervical mobility [M-TAC]to provide a high index of sensitivity and specificity for prediction of difficult airway.

Methodology: Two hundred patients, scheduled for general anaesthesia (GA) requiring endotracheal intubation for elective surgical procedures were evaluated in this prospective, double blind, case control study. Airway assessment was done first by MMC and then by combination of tests (M-TAC). Anaesthesiologists assessing and managing airway were different and blinded for airway parameter. Difficult intubation was assessed by modified Cormack and Lehane grading (CL) and correlated with pre-operative airway assessment. Patients, failed to be intubated, were intubated by different methods and excluded from the study.

Results: Our results showed that M-TAC in comparison to MMC had  higher sensitivity (96.29% vs 74.07%), specificity (81.50% vs 73.41%), positive predictive value (PPV) (44.83% vs 30.30%). and negative predictive value (NPV) (99.30%vs 94.78%). The odd’s ratio (114.60, (95% CI14.99 to 875.64 vs 7.89, 95% CI) was3.130 to 19.882, positive likelihood ratio (LR) was (1.20 vs 1.02), negative LR(1.17 vs 0.99) in predicting difficult airway.

Conclusion: M-TAC, as pre operative assessment test gives better prediction of difficult airway and therefore decreases the adverse outcome incidence related to unanticipated difficult airway though requires precision and time.

Keywords:  endotracheal intubation, laryngoscopy, airway management, general anaesthesia.

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Dr Lalit Mohan

Senior Resident, Department of Radiotherapy, Govt Medical College, Haldwani, Uttarakhand, India

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