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

Abstract

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. Methods: Ultrasound measurements were performed preoperatively in 25 patients with morbid obesity, measuring the HMD in the neutral, ramped, and maximum hyperextended positions. Pre-epyglotic soft tissue thickness, Mallampati and upper lip bite test scores were recorded. Cormack-Lehane grading was considered as an outcome variable in the Receiver Operating Characteristics curve analysis. Results: HMD in the neutral, ramped and maximum hyperextended positions presented similar sensitivities, 100% [39.8-100.0]. For HMD, specificity was 42.86% [21.8-66.0] in the neutral position, 61.9% [38.4-81.9] in the ramped postion, and 71. 4% [47.8-88.7] in the maximum hyperextended position. For HMDR1, the cut-off value was 1.12. This threshold provides 75% [19.4-99.4] sensitivity and 76. 2% [52.8-91.8] specificity. For HMDR2, a cut-off value of 1.23 provides 100% [39.8-100.0] sensitivity and 90.5% [69.6-98.8] specificity. Conclusion: HMDR2 seems to have superior diagnostic accuracy in predicting difficult laryngoscopy in the obese population compared to HMDR1, as well as compared to the HMD in the neutral, ramped, and maximum hyperextended positions.

Preoperative X-ray C2C6AR is Applicable for Prediction of Difficult Laryngoscopy in Patients With Cervical Spondylosis

“…Firstly, in our study, all participants were cervical spondylosis patients with abnormal lower cervical spines below hyoid level and usually there was no signi cant difference in the upper cervical spines. The median of HMDR in the easy laryngoscopy group was 1.21 which was smaller than the median of HMDR (1.34) in the study by Petrisor et al However, the median of HMDR in the di cult laryngoscopy group was 1.22 which was in accordance with the median of HMDR (1.21) in the study by Petrisor et al [18]. Secondly, the HMDR measured by ultrasound in other studies could not eliminate the in uence of soft tissue on the indicator measurement.…”

“…HMD is measured between the anterior border of the chin and the anterior border of the hyoid [17]. In the study by Petrisor et al [18], HMDR seemed to have superior diagnostic accuracy with a cut-off value of 1.23 provides 100% (39.8-100.0) sensitivity and 90.5% (69.6-98.8) speci city for the prediction of di cult airway in the obese population.…”

Preoperative difficult airway prediction using suprahyoid and infrahyoid ultrasonography derived measurements in anesthesiology

“…A similar study conducted on obese patients, but from a different geographical population, did not confirm this method and could not differentiate the patients with easy versus difficult intubation [14]. In a pilot study we conducted on 25 morbidly obese patients, the sensitivity and specificity of the method were 75% [23].…”

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

“…Because of the wide variability in clinical studies, ultrasound evaluation of the HMDR might be of interest, especially that the scanning technique is simple. With a cutoff of 1.24, the sensitivity of ultrasound-measured HMDR was 86-100%, while the specificity was 72-90.5% in the non-obese and obese populations [10,11]. Using ROC analysis, Koundal et al found a cutoff of 1.08-1.085 for HMDR echo , with 65-75% sensitivity and 77-85% specificity [9,12].…”

“…The diagnostic accuracy of this parameter varied widely in subsequent studies, suggesting that evaluation of clinical parameters might be operator-dependent or that there might be difficulties regarding the palpation of the hyoid bone in certain patients [4][5][6][7][8]. In the last years, ultrasound measurements were applied for the hyomental distance ratio (HMDR echo ), also with variable sensitivity and specificity [9][10][11][12][13]. However, until now, each of the previous studies on HMDR focused on a single technique of measurement, either clinical or ultrasonographical, and no study compared the two.…”