Analysis Of Multiple Factors And Preoperative Prediction For The Difficult Laryngeal Exposure In Patients Undergoing Suspension Laryngoscopy

Research background:The laryngeal microsurgery in suspension laryngoscopy is a conventional operation in department of Otorhinolaryngology. It has the advantages of simple operation, less injury, rapid postoperative recovery etc. Especially in recent years, the transoral laryngeal microsurgical technique has become a widely accepted procedure. Except for the diagnosis of laryngeal diseases, transoral laser microsurgery treatment and transoral robotic surgery has gradually been used to the surgical treatment of certain malignant and benign laryngeal lesions. In these operations, the adequate exposure and good visulation of glottis plane is considered to be the essential condition of laryngeal microsurgery. However, due to individual differences in patients, especially in patients with head and neck anatomy structure differences, the surgical operation always be effected because of inadequate exposure in suspension laryngoscopy of partial patients, which even lead to operation abortion.Objective:1, To find out the related factors by analysis of the general factors and anatomic factors of head and neck which is presently thought to be related to difficult laryngeal exposure, then establish a simple and practical prediction model2, To investigate other effective factors conducive to glottis exposure in support laryngoscope.Methods:193 cases of patients undergoing suspension laryngoscopy in Shaoxing second hospital since 2013-5-1 to 2014-12-30 were collected. All these patients were divided into difficult exposure group and non difficult exposure group according to intraoperative glottis exposure.5 general parameters including age, gender, BMI index, Yamamoto index, modified Mallampati index and 13 anatomic parameters including neck circumference, mouth opening, thyroid-mandible angle, hyoid-mental distance(HMD), thyroid-mental distance(TMD), sternum-mental distance(SMD), horizontal thyroid-mental distance(HTMD), vertical thyroid-mental distance (VTMD) (the last five parameters were separately measured in natural position and full extension position of head) were compared. We analysed single factor correlation between each parameter and difficult laryngeal exposure. Then we perform the analysis of multiple factors. The data was processed with SPSS 18 software and MedCalc11.4 software. We used t test to analyse measurement data of single factors and Chi square test to analyse sex constituent ratio while we used two classification logistic regression analysis in multi factor analysis. P< 0.05 was defined as the difference was statistically significanResults:In 193 patients, according the Cormack-Lehane classification,100 cases were grade 1,58 cases were grade 2,32 cases were grade 3,3 cases were grade 4. Grade 1 and grade 2 in a total of 158 cases were brought into non difficult exposure group, grade 3 and grade 4 in a total of 35 cases were brought into difficult exposure group. In 18 parameters,9 parameters including BMI index, Yamamoto index, modified Mallampati index, neck circumference, mouth opening, full extension HMD, full extension TMD, full extension SMD and TMA were related to difficult laryngeal exposure. In these 9 parameters,7 parameters except Yamamoto index and modified Mallampati index were imported MedCalc to execute ROC curve analysis. According to the results of area under the curve (AUC), the AUC of neck circumference, full extension TMD, TMA, mouth opening and BMI were greater than 0.7, so they have high diagnostic value. By logistic stepwise regression analysis, the prediction equation was:logit (P)=43.395+ 3.378*TMD+1.561*SMD+0.785*TMA.Conclusions:1. Obesity and multiple parameters related with head and neck anatomy were associated with difficult laryngeal exposure, comprehensive analysis of the factors contribute to the preoperative prediction.2. Multi factor forecasting equation:logit (P)=43.395+3.378*TMD(full extension) +1.561*SMD(full extension)-0.785*TMA can be used as a simple and effective method for preoperative prediction.3. The reasonable combination of single factor and multi factor analysis method can predict the difficult laryngeal exposure before operation.