The Ratio of Height to Thyromental Distance (RHTMD) and Height to Sternomental Distance (RHSMD) as the Predictive...

Area of Science:

• Anesthesiology
• Airway Management
• Predictive Diagnostics

Background:

• Pre-operative evaluation is crucial for identifying patients at risk of difficult intubation.
• Thyromental distance (TMD) is a common but unreliable predictor due to variations in patient body proportions.
• Newer metrics are needed to improve the accuracy of difficult airway prediction.

Purpose of the Study:

• To evaluate the efficacy of the ratio of height to thyromental distance (RHTMD) and the ratio of height to sternomental distance (RHSMD) as predictors of difficult intubation.
• To compare the predictive values of RHTMD and RHSMD against established methods.

Main Methods:

• A prospective study involving 400 consecutive patients requiring anesthesia with intubation.
• Pre-operative measurement of RHTMD and RHSMD.
• Classification of difficult intubation using Cormack and Lehane grade 3 or 4.
• Calculation of sensitivity, specificity, positive, and negative predictive values.

Main Results:

• The ratio of height to thyromental distance (RHTMD) demonstrated superior predictive value compared to the ratio of height to sternomental distance (RHSMD) (p=0.001).
• RHTMD showed 62.5% sensitivity, while RHSMD had 37.50% sensitivity.
• RHTMD exhibited better specificity, positive predictive value, negative predictive value, and overall accuracy.

Conclusions:

• The ratio of height to thyromental distance (RHTMD) is a more precise and reliable predictor for anticipating difficult intubation compared to RHSMD.
• RHTMD offers improved accuracy in pre-operative airway assessment for surgical patients.