Accuracy of ultrasound-measured airway indicators in predicting difficult laryngoscopy / 中华麻醉学杂志

ABSTRACT

Objective:To evaluate the accuracy of ultrasound-measured airway indicators in predicting difficult laryngoscopy.Methods:A total of 104 American Society of Anesthesiologists physical status Ⅰ or Ⅱ patients, aged 18-70 yr, undergoing elective operation under general anesthesia, were selected.The airway was evaluated before induction of anesthesia, body mass index (BMI), neck circumference, mouth opening, thyromental distance and modified Mallampati classification were recorded, and mandibular condylar mobility, distance from skin to under surface of tongue, hyomental distance and distance from skin to epiglottis were measured by ultrasound.Anesthesia induction was performed after the end of measurement, and direct laryngoscopy was performed after mask pressure ventilation.Cormack-Lehane (CL) grade was recorded, and difficult laryngoscopy was defined as CL grade≥2b.The patients were divided into non-difficult laryngoscopy group (group NDL) and difficult laryngoscopy group (group DL) according to the view obtainable during laryngoscopy.The factors of which P values less than 0.05 would enter the logistic regression analysis.The accuracy of each index in predicting difficult laryngoscopy was evaluated using the area under the receiver operating characteristic curve (AUC) and 95% confidence interval (CI). The critical value was determined according to Youden index, and the sensitivity and specificity were calculated. Results:Compared with NDL group, BMI, depth of epiglottis and the incidence of modified Mallampti≥grade Ⅲ were significantly increased, and the mouth opening and thyromental distance were decreased in goup DL ( P<0.05). The AUC (95%CI) of modified Mallampti classification and the depth of epiglottis for difficult laryngoscopy prediction were 0.728 (0.619-0.836) and 0.833 (0.743-0.924), respectively.When the critical value of depth of epiglottis was 2.125 cm, the sensitivity and specificity of predicting difficult laryngoscopy were 65.71% and 89.86%, respectively. Conclusion:Ultrasound-measured depth of epiglottis can accurately predict the difficult laryngoscopy.