Prediction of Difficult Endotracheal Intubation through Assessment of Anatomical and Anthropometric Indicators

Objective: Predictions of laryngoscopy and difficult endotracheal intubation have been yet considered as one of the major problems in general anesthesia during surgical procedures. Therefore, this study aimed to evaluate a method for prediction of difficult endotracheal intubation in patients undergoing surgical procedures through assessment of some anatomical and anthropometric indicators, like neck circumference (NC), thyromental distance (TMD) and body mass index (BMI). Materials and Methods: This cross-sectional descriptive and analytical study was carried out at the Amir-Al-Momenin Hospital, Zabol, Iran, during 2020-2021. Two hundreds patients aged 18 to 60 years with American Association of Anesthesiologist (ASA) physical status I and II underwent surgical procedures requiring general anesthesia with airway intubation. The patients were selected using convenience sampling method. Information on age, gender, weight, height, TMD, and NC were compared between two groups of difficult intubation (n=100) and easy intubation (n=100). Univariate and multivariate logistic regression models were used to identify the independent predictors of difficult intubation. Receiver Operating Characteristic (ROC) curve was also used to make different measures for predictive accuracy by comparing the area under the curves.The data were analyzed using Stata V.11 software. A P value less than 0.05 was considered statistically significant. Results: Of 200 patients, 61(30.5%) experienced difficult intubation. The adjusted odds ratios (P values) for NC, TDM, BMI/TDM and NC/TDM were 1.90(0.7), 0.11(0.007), 127.66(<0.001) and 6.80(<0.001), respectively. ROC curve analysis indicated that largest area under the curve belonged to BMI /TDM. Conclusion: The present study indicated an obvious relationship between some of anatomic indicators, such as TMD/NC and BMI/TMD, with difficult endotracheal intubation. However, the vast experience and skills of anesthesiologists and the use of alternative methods may play an important role in this regard.