Prediction Of Difficult Laryngoscopy By Ultrasound Quantification Of Neck Soft Tissue

Objective Prediction of difficult laryngoscopy plays a important role in airwaymanagement and is challenging. At present, there are many predictors and evaluativemethods for difficult airway. Ultrasound imaging technique has recently emerged as anovel, simple, portable, noninvasive tool helpful for clinical diagnose. Recentlyanesthesiologists pay more attention to the application of ultrasound in airwaymanagement. We quantified the thickness of the neck soft tissue to find a effectivepredictor and evaluative method for difficult airway.Methods100patients older than18years old who received general anesthesiawere selected. Patients who had upper airway pathologies, neck movementlimits,thyromental<6cm and mouth opening<3cm were excluded from the study. Wequantified the thickness of neck soft tissue from skin to vocal cord anteriorcommissure at the throid cartilage using ultrasound. Neck circumference and neckdiameter according to the circumference were considered predictors of difficultairway. After rapid induction of anesthesia with muscle relaxation, the laryngoscopywas carried with a size3Macintosh blade. The laryngoscopy view was gradedaccording to Cormack and Lehanes’s scale.Results There were seven cases(7%) of difficult laryngoscopy. Patients withdifficult laryngoscopy had a larger neck circumference (460.7±33.1mm) than patientswith easy laryngoscopy (402.9±40.7mm）(P<0.05).The difficult laryngoscopy patientsalso had much more soft tissue（22.8±2.8mm）than patients with easy laryngoscopy（12.2±2.3）(P<0.05), as well as the ratio of neck diameter to the thickness of necksoft tissue[（6.7±0.7）vs（10.7±1.6）,(P<0.05)] Conclusion Quantification the thickness of neck soft tissue using ultrasound is aeffective predictor and evaluative method for difficult airway. The ultrasoundvisualization of airway image was one of the suitable methods to airway mangemant.