The predictive value of skin-to-epiglottis distance to assess difficult intubation in patients who undergo surgery under general anesthesia

Abstract

Background: Intubation is crucial in the management of anesthesia because it is related to the maintenance of oxygenation and ventilation during general anesthesia. Clinical markers for predicting difficult airway have limitations, including requiring coordination with patients. The use of ultrasonography (USG) to measure the distance of the skin to epiglottis is expected to estimate the difficulty level of intubation. Patients and Methods: This was a cross-sectional study of 128 patients who underwent surgery under general anesthesia. We examined the skin-to-epiglottis distance using US prior to surgery. We then assessed the Cormack–Lehane scores during direct laryngoscopy for intubation. The unpaired t-test was used to assess differences in the skin-to-epiglottis distance between patients with easy intubation (Cormack–Lehane I and IIa) and difficult intubation (Cormack–Lehane IIb, III, and IV). Results: The cutoff value of skin-to-epiglottis distance between easy and difficult intubation was 26.05 mm. The sensitivity and specificity of this method to predict difficult airway were 69.4% and 93.5%, respectively. The positive and negative predictive values were 80.6% and 88.7%, respectively. Conclusion: The skin-to-epiglottis distance of >26.05 is a risk factor for difficult intubation.