Ultrasound guided Measurement Of Mandible -Hyoid Bone - Glottis Angle & Distance From Glottis To The Upper Edge Of The Thyroid Cartilage to Predict Difficult Laryngoscopy

Airway assessment is an essential aspect of pre-anaesthesia evaluation. Until now many traditional bedside clinical predictors were used to predict difficult laryngoscopy. However these parameters have limited specificity to diagnose unanticipated difficult airway.Studies have shown that non-invasive ultrasonography is used for evaluating upper airway anatomy and calculate distances between anatomical structures which can aid in prediction of difficult laryngoscopy. Aim of our study is to predict difficult laryngoscopy by USG guided measurement of the angle between mandible - hyoid Bone - glottis and distance from the glottis to the upper edge of thyroid cartilage. Primary objective of this study is to perform USG guided measurement of angle between mandible - hyoid Bone - glottis and distance from the glottis to the upper edge of thyroid cartilage and secondary objective. is to correlate the above-mentioned USG parameters with cormack lehane grading to predict difficult laryngoscopy. Our study is prospective interventional study performed in operation theatres. The sample size of this study is 97 based on statistical analysis. The subjects will be selected based on inclusion criteria like age >18yrs & <65 yrs, patients posted for elective surgeries under GA with tracheal intubation, ASA I&II. Pregnancy patients, obese patients, patients with maxillofacial deformities or fractures, cervical spine instability, patients requiring rapid sequence induction, patients who refused to give consent ,patients with neck swelling will be excluded. The methodology of this study is that on previous day of surgery pre-op anaesthesia evaluation will be done for measurement of usg parameters patient will be placed in supine position with their head and neck in maximal extension and usg of airway will be done by anaesthetist and angle between mandible-hyoid bone and glottis and distance from the glottis to the upper edge of the thyroid cartilage will be measured.On the day of surgery patient will be positioned in sniffing position using a head ring and after the induction of general anaesthesia direct laryngoscopy with macintosh blade will be performed by other anaesthetist who will be blinded to usg measurements and cormack lehane grade of larynx will be noted. The differences will be assessed with the help of statistician.