Airway sonography fails to detect difficult laryngoscopy in an adult Veteran surgical population

Abstract

ObjectiveTo evaluate ultrasound's utility to detect difficult laryngoscopy in a preoperative setting. MethodsThis single-site, prospective, cross-sectional, within-subjects study was performed at a Veterans Affairs Medical Center with 144 subjects. The sonographic independent variables included sonographic hyomental distance (HMD) and anterior neck thicknesses at the hyoid bone (HB), thyrohyoid membrane (THM), and vocal cords (VC). Additional independent variables were standard airway indicators of BMI, neck circumference, obstructive sleep apnea, snoring, abnormal upper teeth, jaw mobility, interincisor gap, Mallampati score, thyromental distance and neck range of motion. The outcome variable was the modified Cormack-Lehane Grade (CLG). ResultsThere was no significance found among the four sonographic measurements or their derived ratios in predicting difficult laryngoscopy. Correlation analysis between the sonographic measurements did find significance of the HMD:HB (p = 0.040) and the HB:THM (p = 0.44) ratios. However these ratios had a weak correlation at −0.172 and −0.168 respectively. Standard airway indicators did not demonstrate significance in predicting the difficult airway, sans obese patient with neck circumference (p = 0.016). DiscussionThis study demonstrated ultrasonography in predicting difficult laryngoscopy lacked utility. Ultrasound utilization as an efficacious means of difficult airway assessment requires further research with a larger sample size. Further studies using sonography on those patients with known difficult airways may provide data to determine if ultrasound has utility in predicting difficult laryngoscopy.