Research Of Application Of Ultrasound In The Prediction Of Difficult Laryngoscope Exposed

Objective: This study is on the basis of airway evaluation methods commonly used in clinical,application of ultrasound scanning participants airway anatomic structure and measurement of the airway measurement by ultrasound associated with difficult laryngoscope exposed(DLE),and compared with conventional airway evaluation methods,so that we can evaluate the value of ultrasound in the airway evaluation.Methods: The research included adult patients(over the age of 18)who underwent elective surgical operations under general endotracheal anesthesia,American Society of Anesthesiologists physical status 1-2.With conventional methods before the induction of anesthesia airway for airway assessment,and then measure the airway by ultrasound and record the tongue width and thickness,the hyomental distance at the extreme of head extension,distance to the posterior surface of the tongue at the level of the tip of the soft palate and oral soft tissue area.The laryngoscopic view was graded using Cormack and Lehane classification by the same anesthesiologist on the day of surgery.The classification includes four grades,Grades III and IV imply the impossibility to visualize the glottis,thus being predictors of DLE.For comparing the differences between the patients with and without DLE,the independent sample t test screening was applied in the continuous measurement data,however,the counting data using ? squared inspection.Then through multivariate Logistic regression analysis and relative risk estimates.By determining the sensitivity,specificity,positive likelihood ratio and negative likelihood ratio of the observed scoring systems in predicting difficult laryngoscope exposed,the receiver operating characteristic curve(ROC curve)was used.Results: 204 cases are all included in the statistical analysis.There have no trouble happened mask ventilation,20 cases of difficult laryngoscope exposed and no one in difficult endotracheal intuition.The occurrence of DLE does not exist significant differences in sex and age.Through multivariate logistic regression analysis,the ultrasonic measurement of the tongue thickness(OR:4.739,95% CI : 1.030-18.919),hyomental distance at the extreme of head extension(OR:0.103,95% CI:0.021-0.516)and distance to the posterior surface of the tongue at the level of the tip of the soft palate(OR:10.235,95%CI: 3.314-31.710)was proved to be statistically insignificant(P<0.05).The area under the ROC curve of the hyomental distance,the tongue thickness,the distance to the posterior surface of the tongue at the level of the tip of the soft palate and the thyromental distance are 0.644,0.846 0.869 and 0.778,(P<0.05).The cut–off has a value of the tongue thickness is 2.97 cm and distance to the posterior surface of the tongue at the level of the tip of the soft palate is 6.34 cm from ROC curve.The sensitivity and the specificity of the tongue thickness is 85% and79.9%,positive likelihood ratio is 4.23 and negative likelihood ratio is 0.19,and the sensitivity and the specificity of the distance to the posterior surface of the tongue at the level of the tip of the soft palate is 75% and 91.3%,positive likelihood ratio is 8.62 and negative likelihood ratio is 0.17,while the sensitivity,specificity,positive likelihood ratio and negative likelihood ratio for conventional airway evaluation methods were as follows: thyromental distance:70%,75%,2.80 and 0.27;Mallampati score:85%,88%,7.08 and 0.17.Conclusion: 1.Ultrasound index including tongue thickness and distance to the posterior surface of the tongue at the level of the tip of the soft palate have higher sensitivity and specificity than traditional assessment methods,then more diagnostic value than conventional evaluation methods.2.The cut–off has a value of the tongue thickness is 2.97 cm and distance to the posterior surface of the tongue at the level of the tip of the soft palate is 6.34 cm from ROC curve.