ACCURACY OF PREOPERATIVE ULTRASONOGRAPHIC AIRWAY ASSESSMENT IN PREDICTING DIFFICULT LARYNGOSCOPY IN ADULT PATIENTS

Abstract

BACKGROUND AND OBJECTIVES: At present , neck ultrasonography is used as a tool in predicting difficult airway. There are no standardized ultrasonographic criteria which help to predict difficult airway .Objective is to ultrasonographically assess anterior neck soft tissue thickness preoperatively based on 2 parameters-DSHB(minimal distance from hyoid bone to skin ) and DSEM(distance from skin to epiglottis midway between hyoid bone and thyroid cartilage ) and find out if the above two USG parameters can predict difficult airway in adults by correlating with CL grading. MATERIALS AND METHODS: After obtaining ethical committee clearance and patient consent, this study was conducted on 96 patients aged between 18-60 years belonging to ASA- I and II admitted for elective surgery under general anaesthesia with endotracheal intubation at R. L. Jalappa Hospital and Research centre, Tamaka, Kolar in the period from January 2020 to May 2021. Exclusion criteria were patients with anticipated difficult airway cases like obesity, pregnancy ,head and neck anatomical pathologies , maxillofacial anomalies and edentulous patients .Sonography of airway was first performed preoperatively by an anaesthesiologist along with noting down the standard clinical tests like Mallampati grading .Sonography of the airway included two parameters –DSHB and DSEM . Patient was later classified as easy or difficult laryngoscopy on the basis of USG parameters criteria from literature available . DSHB >0.66cm - predicted to be difficult airway and DSHB <0.66cm - predicted to be easy. DSEM >2.03cm- predicted to be difficult airway and DSEM <2.03cm - predicted to be easy. XXI After induction of anesthesia , direct laryngoscopy performed in the sniffing position by another anaesthesiologist using appropriate size Macintosh blade and Cormack Lehane grade noted. CL grade I and II considered to be easy laryngoscopy . Quantitative data was presented by Mean SD confidence interval ,qualitative data was presented in percentage and P values less than 0.05 considered statistically significant. To determine discriminative power of individual tests,receiver operating characteristic (ROC)curve , area under curve (AUC) with 95%confidence interval was noted . RESULTS: The two USG parameters –DSHB ,DSEM may be used to predict difficult laryngoscopy in adult patients as there is a very strong statistical significance between the two. Out of the two ,DSHB seems to have a better diagnostic value in our study. CONCLUSION: To conclude , our study showed that USG parameters DSHB and DSEM may aid in predicting difficult laryngoscopy as a strong statistical significance was present between sonographic measurements and CL grading. Also ,DSHB appeared to have a better diagnostic value for prediction of difficult airway .