Evaluation of Point-of-care Ultrasound of Airway to Predict Difficult Laryngoscopy and Intubation in Intensive Care Unit Patients.

Abstract

Background: To evaluate the role of ultrasound (US) in the assessment of the airway and to determine whether US has the potential to serve as effective, noninvasive and less time-consuming method for the diagnosis of difficult intubation in ICU patients.

Patients and methods: This cross-sectional study was carried in 152 critically ill patients who underwent intubation in the ICU from December 2022 to April 2024. Prior to intubation thyromental height (TMH) and hyomental distance ratio (HMD-R) was measured using a scale and distance from skin to hyoid bone (SHB) and distance from skin to thyrohyoid membrane (STM) was measured using a US. Direct laryngoscopy was performed using a Macintosh blade, and the Cormack-Lehane (CL) grade was noted without external laryngeal manipulation. The laryngoscopy was classified as easy (CL Grade I and II) or difficult (CL Grade III and IV). The number of attempts at intubation, need for alternative difficult intubation approaches or inability to secure the airway was also noted.

Results: The incidence of difficult airway was 17.76%. The success rate for first-attempt intubation was 96.7%. Based on the receiver operating characteristic (ROC) curve analysis cut-off value of 1.97 cm [95% confidence interval (CI), 0.949-0.996, area under the curve (AUC), 0.972] for anterior soft tissue thickness from the skin to thyrohyoid membrane distinguished the difficult intubation group from the easy intubation group, with a sensitivity of 96.3% and specificity of 86.4%. For the hyoid bone level, a cut-off value of 0.905 cm (95% CI, 0.706-0.887, AUC, 0.797) had a sensitivity of 74.1% and specificity of 74.4%. Anterior soft tissue thickness from the skin to thyrohyoid membrane was a better predictor of a difficult airway. There was a significant correlation between clinical airway assessments and US airway assessments.

Conclusion: Point-of-care US can serve as an independent tool for assessing the airway in intensive care unit (ICU) patients, with anterior soft tissue thickness from skin to thyrohyoid membrane being a superior predictor. Combined models of sonographic and clinical tests could enhance the diagnostic value for identifying difficult intubation cases in ICU patients.

How to cite this article: Mallick S, Das S, Pradhan S, Kar S. Evaluation of Point-of-care Ultrasound of Airway to Predict Difficult Laryngoscopy and Intubation in Intensive Care Unit Patients. Indian J Crit Care Med 2025;29(1):14-20.