Use of Ultrasonographic Parameters in Preoperative Prediction of Difficult Laryngoscopy in Non-Suspected Difficult Airway Patients Undergoing Elective Surgery

Abstract

Background: Ultrasonography represents a valid as well as promising tool for assessing airway preoperatively by detecting identifying upper airways’ essential sonoanatomy. The aim of this work was aimed at assessing the ultrasonographic parameters [distance from skin to epiglottis (DSE) as well as distance from skin to vocal cords (DSVC)] measured in the parasagittal plane, and determine if they could be preoperative indicators for assessing difficult laryngoscopy among cases having non-suspected difficult airway who undergo elective surgical procedure under general anesthesia.Methods: Our prospective observational study involved 100 cases whose ages fell between eighteen and sixty-five yrs, both genders, not suspected to develop a difficult airway following airway evaluation preoperatively utilizing traditional clinical tests and undergoing for elective surgical procedure under GA. While performing direct laryngoscopy: laryngoscopic view underwent grading utilizing the modified Cormack and Lehane grading where grade I and II a deemed to be easy laryngoscopy (group A) while grade IIb, III as well as IV considered to be difficult laryngoscopy (group B).Results: According to DSE, the cut off value was >1.94 with sensitivity 82.35%, specificity 78.31%, PPV (43.7%) as well as NPV (95.6%). The area under the curve exhibited 0.884 indicating statistical significance (p<0.001), Based on DSVC, the cut off value exhibited ≤1.22 with sensitivity 64.71%, specificity 57.83%, PPV 23.9% and NPV 88.9%. AUC exhibited 0.704 indicating statistical significance (P = 0.008). Combining both DSE and DSVC show that sensitivity 70.59%, specificity 100%, PPV 100% and NPV 94.3%. AUC was 0.921 with statistical significance (p<0.001).Conclusion: DSE as well as DSVC measured in the parasagittal plane, are independent valuable US parameters while predicting difficult laryngoscopy among cases having non-suspected difficult airway patients. DSE possesses a better predictive value for difficult laryngoscopy. DSE >= 2.1 -+ 0.17 could predict a difficult laryngoscopy with PPV 43.7% and AUC of 88%, compared with DSVC ≤ 1.19 -+0.09 with PPV 23.9% and AUC of 70%. Combination of both DSE and DSVC provides the ideal prediction as regards difficult laryngoscopy, possessing a PPV of 100% along with AUC of 92%.