Validity of thyromental height test as a predictor of difficult laryngoscopy: A prospective evaluation comparing modified Mallampati score, interincisor gap, thyromental distance, neck circumference, and neck extension

Abstract Background Predicting difficult airway is challengeable in patients with limited airway evaluation. The aim of this study is to develop and validate a model that predicts difficult laryngoscopy by machine learning of neck circumference and thyromental height as predictors that can be used even for patients with limited airway evaluation. Methods Variables for prediction of difficulty laryngoscopy included age, sex, height, weight, body mass index, neck circumference, and thyromental distance. Difficult laryngoscopy was defined as Grade 3 and 4 by the Cormack-Lehane classification. The preanesthesia and anesthesia data of 1677 patients who had undergone general anesthesia at a single center were collected. The data set was randomly stratified into a training set (80%) and a test set (20%), with equal distribution of difficulty laryngoscopy. The training data sets were trained with five algorithms (logistic regression, multilayer perceptron, random forest, extreme gradient boosting, and light gradient boosting machine). The prediction models were validated through a test set. Results The model’s performance using random forest was best (area under receiver operating characteristic curve = 0.79 [95% confidence interval: 0.72–0.86], area under precision-recall curve = 0.32 [95% confidence interval: 0.27–0.37]). Conclusions Machine learning can predict difficult laryngoscopy through a combination of several predictors including neck circumference and thyromental height. The performance of the model can be improved with more data, a new variable and combination of models.

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Comparison of Incidence of Difficult Intubation between Obese and Nonobese Patients, and Comparison of Three Predictors of Difficult Intubation in Obese Patients

Research & Innovation in Anesthesia ◽

10.5005/jp-journals-10049-0011 ◽

2016 ◽

Vol 1 (2) ◽

pp. 41-44

Author(s):

Johann Mathew

Keyword(s):

Tracheal Intubation ◽

Difficult Intubation ◽

Mouth Opening ◽

Difficult Tracheal Intubation ◽

Neck Circumference ◽

Obese Patients ◽

Chi Square ◽

Neck Extension ◽

Difficulty Scale ◽

Nonobese Patients

ABSTRACT Background Anticipating a difficult airway is of prime importance to an anesthesiologist. Data available are inconclusive to say that tracheal intubation is more difficult in the obese. The deficiency occurring with individual factors can be avoided by adopting multiple airway assessment factors. In this study, we aim to compare the incidence of difficult intubation between obese and nonobese patients and compare three predictors of difficult intubation. Study design Prospective observational study. Materials and methods About 250 patients were assigned to two groups, obese and nonobese based on their body mass index. Preoperatively, neck circumference (NC), mouth opening, thyromental distance (TMD), neck extension, NC/TM ratio, Mallampati classification (MPC), and Wilson score (WS) were calculated. Difficulty of intubation was assessed using the intubation difficulty scale (IDS). All tracheal intubations were performed by anesthetists with more than 2 years of experience. Statistical analysis used Data analysis was done with the help of Statistical Package for the Social Sciences (SPSS) version 15, MedCalc version 11, and Epi data software. Qualitative data are presented with the help of frequency and percentage table, and association among various study parameters is done with chi-square test. Results The incidence of difficult intubation determined by the IDS (≥5) was more frequent in the obese group (88.6% in obese vs 11.4% in nonobese). Of the three variables, WS was found to be statistically significant (p < 0.005). Neck circumference to thyromental ratio is a new predictor for difficult tracheal intubation (DTI). But an NC/TM ratio of ≥5 gives high false positive for our population. How to cite this article Mathew J, Gvalani SK. Comparison of Incidence of Difficult Intubation between Obese and Nonobese Patients, and Comparison of Three Predictors of Difficult Intubation in Obese Patients. Res Inno in Anesth 2016;1(2):41-44.

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