Effectiveness Of Airway Ultrasound In Predicting Difficult Airway In Obese Patients

Objective:Tongue thickness,transverse diameter,transverse area,tongue volume,distance from skin to hyoid bone(DSH)and distance from skin to epiglottis were measured by ultrasound in obese people.DSE),distance from skin to vocal cords(DSV),and their predictive effects on difficult laryngoscope exposure and difficult tracheal intubation in obese people were studied,and each index was compared to find a better indicator for predicting difficult laryngoscope exposure and difficult tracheal intubation in obese people.Methods:A total of 100 obese patients,aged 18-70 years,were selected for elective operation.Data were collected and measured the day before surgery,including sex,age,height,weight,body mass index(BMI),neck circumference,inter-incisor distance(IID)and thyromental distance(IID).TMD),Mallampati test modified mallampati test(MMT),the upper lip bite test(ULBT).Before anesthesia induction on the day of surgery,the patient was removed from the occipital supine position,measured DSH,DSE,DSV,tongue thickness,tongue diameter,and tongue longitudinal section area,and calculated tongue volume(tongue volume equals tongue transverse diameter multiplied by tongue longitudinal section area).All of the above measurements were performed by the same anesthesiologist.Laryngoscope exposure was performed after anesthesia by the same physician who did not participate in the data analysis,Cormack-Lehane(C-L)grading was recorded,and endotracheal intubation was completed.The relationship between DSE,DSH,DSV,tongue transverse diameter,tongue thickness,tongue longitudinal cross-sectional area and tongue volume and laryngoscope exposure difficulty and tracheal intubation difficulty was analyzed,and the receiver operating characteristic curve(ROC)was drawn.The truncation values of each index for predicting laryngoscope exposure difficulty and tracheal intubation difficulty were obtained by combining with Jorden index,and the sensitivity and specificity of each index for predicting difficult airway were calculated according to the truncation values.Results:here were a total of 100 subjects in this study,among which 2 were excluded due to the loss of important feature data and 2 were excluded due to the conversion to laryngeal mask after anesthesia.A total of 96 subjects were included in the final statistical analysis.A total of 28 patients(29.2%)had difficulty in laryngoscope exposure: 24 patients in Cormack-Lehane grade Ⅲ and 4 patients in Cormack-Lehane grade Ⅳ.Endotracheal intubation difficulties were observed in 14 patients(14.6%),including 12 patients with Cormack-Lehane grade Ⅲ and 2 patients with Cormack-Lehane grade Ⅳ.According to the difficulty of laryngoscope exposure and tracheal intubation,the patients were divided into DL group: difficult laryngoscope exposure group;NDL group: non-difficult laryngoscope exposure group;DI group: difficult tracheal intubation group;NDI group: non-difficult tracheal intubation group.(1)There were no significant differences in gender,age,mouth opening and neck circumference between DL group and NDL group and between DI group and NDI group(P>0.05).(2)Ultrasonic measurements of DSE,DSH,tongue transverse diameter,tongue longitudinal cross-sectional area and tongue volume were correlated with difficult laryngoscope exposure and difficult tracheal intubation(P<0.05).(3)Area under the ROC cerve,Area under the roc cerve,AUC)were BMI(0.762),TMD(0.646),DSE(0.819),DSH(0.830),tongue diameter(0.668),tongue area(0.688)and tongue volume(0.693),respectively.The areas under the curve for predicting difficult endotracheal intubation were BMI(0.760),TMD(0.763),DSE(0.794),DSH(0.869),tongue diameter(0.716),tongue cross-sectional area(0.707)and tongue volume(0.747),respectively.Conclusion:(1)DSH,DSE,tongue transverse diameter,tongue longitudinal cross-sectional area and tongue volume all have predictive value for difficult airway.(2)When DSH>1.72 cm,the sensitivity and specificity of laryngoscope exposure were 60.7% and 95.6%.When DSH>1.72 cm,the sensitivity and specificity were 78.6% and 89.0%,respectively.(3)By comprehensive comparison,it is concluded that the index DSH has a higher predictive value for difficult airway.