Clinical Ultrasound Measurements of Hyomental Distance Ratio for the Prediction of Difficult Airway in Patients with and without Morbid Obesity.

Purpose: To describe the correlation between clinically measured hyomental distance ratio (HMDR) and the ultrasound measurement (HMDR) in patients with and without morbid obesity and to compare their diagnostic accuracy for difficult airway prediction.

Methods: HMDR and HMDR were recorded the day before surgery in 160 consecutive consenting patients. Laryngoscopy was performed by a skilled anesthesiologist, with grades III and IV Cormack-Lehane being considered difficult views of the glottis.

Ultrasound-based assessment of hyomental distances in neutral, ramped, and maximum hyperextended positions, and derived ratios, for the prediction of difficult airway in the obese population: a pilot diagnostic accuracy study.

Background: Ultrasonography-assessed hyomental distance (HMD) ratio has been found to discriminate between obese patients with Cormack-Lehane grades 1 or 2 vs. those with grades 3 or 4. The aim of our study is to evaluate the performance of the HMD evaluated ultrasonographically in neutral, ramped, and maximum hyperextended positions, as well as for the ratios obtained by dividing the HMD in the ramped position to that in the neutral position (HMDR1) and by dividing the HMD in maximum hyperextension to that in the neutral position (HMDR2), in order to predict the occurrence of Cormack-Lehane grades 3 or 4 during direct laryngoscopy.