Comparison of the diagnostic values of height to hyomental distance ratio and height to thyromental distance ratio in predicting difficult airway in adult patients posted for general anaesthesia

A prospective observational study which includes patient posted for elective surgeries under general anaesthesia aims to identify the better predictor of difficult laryngoscopy between hyomental and thyromental distance. These distances are measured under USG guidance. Calculating the ratio of patient height to hyomental distance and patient height to thyromental distance and comparing with gold standard cormack lehane grading. Finding the sensitivity,specificity, ppv and npv for each ratio and plotting the receiver operator curve which tells about the area under the curve. Higher the sensitivity & specificity , greater the area under the curve better predictor it will be.All the enrolled patients underwent a thorough preoperative evaluation including a detailed history and clinical examination and advised standard operative fasting guidelines.Lab Investigations, chest X ray, ECG were assessed relevant to the patient and surgical requirements.HMD is measured from the distance between bony point of mentum to hyoid bone with head in extension and mouth closed.TMD is measured under bony point of mentum to thyroid cartilage with head in extension and mouth closed.Airway assessment was done by a single anesthesiologist in all cases who would not participate in endotracheal intubation. Difficult airway carts with bougie,styles,video laryngoscope, laryngeal ask airways and fibreoptic bronchoscopeof appropriate sizes are made available in the operating room.