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Height to thyromental distance ratio and height to sternomental distance ratio comparison as difficult airway predictors: A cross-sectional study

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Original Article

Author Details : Rashmi Pal, Anushri Agrawal*, Deepali Valecha, Manish Banjare

Volume : 12, Issue : 1, Year : 2025

Article Page : 118-124

https://doi.org/10.18231/j.ijca.2025.018

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Abstract

Background and Aims: Difficult airway management is a critical concern in anesthesiology, contributing significantly to perioperative morbidity and mortality. Preoperative evaluation using predictive parameters like the Height-to-Thyromental Distance (RHTMD) ratio and the Height-to-Sternomental Distance (RHSMD) ratio aids in identifying patients at risk of difficult intubation. This study aimed to compare RHTMD and RHSMD as predictors of difficult airways in patients undergoing elective surgeries under general anesthesia.
Materials and Methods: A cross-sectional study was conducted involving 150 patients undergoing elective surgeries under general anesthesia. Airway assessments included measurements of Thyromental Distance (TMD), Sternomental Distance (SMD), RHTMD, RHSMD, weight, and height. Direct laryngoscopy was performed using a Macintosh blade by an anesthetist with over three years of experience, and the Cormack-Lehane grade was recorded. Institutional anesthesia protocols were uniformly applied.
Results: Using the Cormack-Lehane grade as the reference standard, RHTMD demonstrated a sensitivity of 88.9%, specificity of 97.7%, and accuracy of 96.67%. RHSMD showed a sensitivity of 83.3%, specificity of 95.5%, and accuracy of 94%.
Conclusions: The Height-to-Thyromental Distance ratio was found to be a more sensitive, specific, and accurate predictor of difficult airways compared to the Height-to-Sternomental Distance ratio. Combining both parameters further improved the predictive reliability, emphasizing the need for an integrated assessment approach in airway evaluation.
 

Keywords: Sternomental distance, Thyromental distance, Difficult airway, Cormack- lehane grade.

How to cite : Pal R, Agrawal A, Valecha D, Banjare M, Height to thyromental distance ratio and height to sternomental distance ratio comparison as difficult airway predictors: A cross-sectional study. Indian J Clin Anaesth 2025;12(1):118-124

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