Evaluation of thyromental height test in prediction of difficult airway in obese surgical patients: An observational study

Machine Learning Predictions and Identifying Key Predictors for Safer Intubation: A Study on Video Laryngoscopy Views

This study develops a predictive model for video laryngoscopic views using advanced machine learning techniques, aiming to enhance airway management's efficiency and safety. A total of 212 participants were involved, with 169 in the training set and 43 in the test set. We assessed outcomes using the percentage of glottic opening (POGO) score and considered factors like the modified Mallampati classification, thyromental height and distance, sternomental distance, mouth opening distance, and neck circumference. A range of machine learning algorithms was employed for data analysis, including Random Forest, Light Gradient Boosting Machine, K-Nearest Neighbors, Support Vector Regression, Ridge Regression, and Lasso Regression. The models' performance was evaluated on the test set, with Root Mean Squared Error values ranging from 20.4 to 21.9. SHapley Additive exPlanations value analysis revealed that age is a consistent and significant predictor of POGO score across all models, highlighting its critical role in the predictive accuracy of these techniques.

Evaluation of neck-circumference- thyromental- distance ratio as a predictor of difficult intubation: A prospective, observational study

Background and Aims

Preoperative identification of difficult airway and subsequent planning is of utmost importance for a patient's safety. Previous studies have identified the ratio of the neck circumference (NC) to the thyromental distance (TMD); NC/TMD as a reliable predictor of difficult intubation in obese patients. But there is a lack of studies evaluating the NC/TMD in non-obese patients. Therefore, the aim of this study was to compare the NC/TMD as a predictor of difficult intubation in both obese and non-obese patients.

Methods

A prospective, observational study was conducted after obtaining institutional ethics committee clearance and written and informed consent from each patient. One hundred adult patients undergoing elective surgeries under general anaesthesia with orotracheal intubation were included in this study. Difficulty in intubation was assessed using the Intubation Difficulty Scale. The NC/TMD was calculated and the predictive accuracy of NC/TMD and other established parameters in obese and non-obese patients were compared.

Results

Univariate logistic regression analysis showed that gender, weight, body mass index, inter-incisor gap, Mallampati classification, NC, TMD, sternomental distance, and NC/TMD had a significant association with difficult intubation. NC/TMD has a higher sensitivity, specificity, and positive and negative predictive value with better predictability in comparison to other parameters.

Conclusion

The NC/TMD is a reliable and better predictor of difficult intubation in both obese and non-obese patients in comparison to NC, TMD, and sternomental distance alone.

Use of the Thyromental Height Test for Prediction of Difficult Laryngoscopy: A Systematic Review and Meta-Analysis

The thyromental height test (TMHT) has been proposed as a novel single clinical test for predicting difficult laryngoscopy (DL), though consequent studies have put forward various estimates when verifying its reliability. This systematic review and meta-analysis aimed to provide a comprehensive evaluation of the predictive value of TMHT for DL. A computerized search of CNKI, CQVIP, EBSCO, PubMed, SinoMed, and Wanfang Data was conducted on 1 June 2022. Prospective cohort studies reporting diagnostic properties of TMHT in relation to Cormack and Lehane grading in patients aged more than 16 years, either sex, scheduled for surgery under general anesthesia, requiring tracheal intubation with direct laryngoscopy were included in this analysis. Data was extracted or calculated, and meta-analysis was done by the Stata MIDAS module. A total of 23 studies with 5896 patients were included in this analysis. Summary estimates of all included studies are as follows: sensitivity 74% (95% CI, 68-79%); specificity 88% (95% CI, 81-92%); diagnostic odd ratio, 20 (95% CI, 10-40); positive likelihood ratio, 5.9 (95% CI, 3.6-9.6); and negative likelihood ratio, 0.30 (95% CI, 0.23-0.39). Summary sensitivity and specificity for studies with a prespecified threshold were 82% (95% CI, 71-89%) and 94% (95% CI, 87-98%), respectively. The estimated area under curve (AUC) was 85% (95% CI, 81-88%). There was no significant threshold effect but significant heterogeneity in both sensitivity and specificity. Heterogeneity in sensitivity became insignificant after removing two outliers of sensitivity analysis. It is concluded that THMT has an overall optimal predictive value for DL in adult patients with diverse ethnicity and various risk factors, displaying better predictive values in a large patient population comparing to other recent reported bedside assessments and a previous meta-analysis. As significant heterogeneity brought by un-standardized application of external laryngeal manipulations in the included studies may have biased the results of this meta-analysis, the actual predictive value of TMHT for DL still awaits further studies with good designs and large sample sizes for better determination.