Ultrasonic Measurement Combined With Upper Lip Bite Test To Predict Difficult Airway

Objective : To explore the feasibility of using ultrasound to measure the thickness of the pharyngeal wall,the angle between the epiglottis and the glottis,the temporomandibular ankle mobility combined with the upper lip bite test to predict difficult mask ventilation and difficult laryngoscope exposure.Methods: A total of 159 patients with selective endotracheal intubation under general anesthesia were collected,ASAI-II grade,aged 18-75 years old.Preoperative patient-related information collected includes: gender,age,body mass index,upper lip bite test,ultrasound measurement of temporomandibular ankle range of motion,thickness of the pharyngeal wall,and the angle between the epiglottis and the glottis.During the induction of anesthesia,patients were divided into difficult mask ventilation group and non-difficult mask ventilation group,difficult laryngoscopy exposure group and non-difficult laryngoscopy exposure group by assessing the degree of mask ventilation difficulty and the classification of laryngoscopy exposure.Collect and summarize the data,analyze the significance of various indicators for difficult mask ventilation and difficult laryngoscope exposure.Results: A total of 159 patients were collected and successfully included in the statistical analysis.There were 30 cases in the difficult mask ventilation group,129 cases in the non-difficult mask ventilation group,30 cases in the difficult laryngoscopy exposure group,and 129 cases in the non-difficult laryngoscopy exposure group.Face mask ventilation: Upper lip bite test grades 2 and 3 are statistically significant in predicting difficult mask ventilation(p﹤0.05),positive predictive value 25.6%,negative predictive value 96.0%,sensitivity 93.3%,specificity 37.2%.At the same time,the analysis showed that patients with a body mass index greater than 28.2kg/m2 had a higher risk of difficult mask ventilation,with a sensitivity of 0.867 and a specificity of 0.922.Ultrasonic measurement of the thickness of the pharyngeal lateral wall was statistically significant(p<0.001).The area of the lower right curve of the ROC was 0.931,95%CI(0.891-0.971),and the best cut-off point 0.855 cm was calculated by the Youden index.,The sensitivity is 0.933,and the specificity is 0.884.After comprehensive pharyngeal wall thickness,body mass index,and upper lip bite test,the area of the lower right curve of the ROC is 0.958(0.929-0.987),the sensitivity is 1.000,and the specificity is 0.868.Age,gender,ultrasound measurement of temporomandibular ankle range of motion,epiglottis and glottis angle,and difficult mask ventilation were not statistically significant(p>0.05).Difficult laryngoscopy exposure:Levels 2 and 3 of the upper lip bite test have certain clinical value for predicting difficult laryngoscopy exposure(p﹤0.05),with a positive predictive value of24.7%,a negative predictive value of 94.0%,and a sensitivity of 90.0 %,the specificity is 36.4%.Ultrasonic measurement of the angle between the epiglottis and the glottis is less than 45.18°,which is highly suggestive of difficult laryngoscope exposure(p<0.001).The ROC curve is used to calculate the area of the lower right curve to be 0.969(95%CI 0.945-0.992),with a sensitivity of 0.946 and Specificity is 0.900.The area of the lower right curve of the epiglottis and glottis angle combined with the upper lip bite test is 0.973(0.952-0.995),the sensitivity is 1.00,and the specificity is 0.960.There was no significant correlation between gender,age,body mass index,ultrasound measurement of pharyngeal wall thickness,temporomandibular ankle mobility,and difficult laryngoscope exposure(p>0.05).Conclusion: 1.Ultrasonic measurement of the thickness of the pharyngeal wall greater than 0.855 cm suggests that there may be difficult mask ventilation,and when the angle between the epiglottis and the glottis is less than 45°,it indicates difficult laryngoscope exposure.2.The upper lip bite test can predict difficult mask ventilation and difficult laryngoscope exposure.3.Combining the three prediction methods of pharyngeal wall thickness,upper lip occlusion test and body mass index can improve the accuracy of predicting difficult mask ventilation.Epiglottis and glottis angle combined with upper lip occlusion test can better predict difficult laryngoscope exposure.