Airway management, including the ability to intubate, is a basic skill required in the repertoire of an anaesthesiologist. Inability to maintain a patent airway results in inadequate ventilation and oxygenation leading to hypoxic brain damage and death. The incidence of difficult intubation in surgical patients undergoing general anaesthesia is estimated to be approximately 1-18% whereas that of failure to intubate is 0.05 -0.35%.(1,2,3) Various methods have been used for prediction of difficult laryngoscopy comparing either individual parameters(4,5) or by using scoring systems.(6,7) Although, upper lip bite has been shown to be a promising test in its introductory article,(5) repeated validation in various populations is required for any test to be accepted as a routine test.
In our study, the two most commonly used tests, namely ‘Modified Mallampati classification’(MMC) and ‘Thyromental distance’(TMD) are compared with
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Class III: soft palate and base of uvula visible. Class IV: only hard palate visible. Classes I and II were considered predictive of easy intubation whereas classes III and IV were considered predictive of difficult intubations.
TMD is defined as the distance from the mentum to the superior notch on the thyroid cartilage when the patient’s neck is fully extended. It was measured with a ruler in the upright sitting position.(8,12,13) A TMD less than 6 cm was considered to be predictive of difficult intubation.(4,14) To maintain blinding, only one anesthetist assessed the predictive tests while other blinded anesthetists performed the patients’