Applications and prospects of ultrasound in difficult airway management: A narrative review

Management of difficult airways remains a core challenge in anesthesiology, critical care, and emergency medicine, with adverse event rates approximately 1%-3%, which can lead to severe hypoxic brain injury or even death. Ultrasound, with its non-invasive, real-time, and portable characteristics, has become an essential auxiliary tool for predicting and managing difficult airways.

This review provides clinical physicians with a framework for the application of ultrasound in predicting and managing difficult airways, thereby enhancing the safety and precision of airway management, and focuses on analyzing the diagnostic performance of ultrasound parameters such as skin-to-epiglottis distance, tongue thickness, and thyrohyoid membrane thickness, and explores their application disparities among various populations (obese, obstetric, pediatric).

Utilizing terms like "airway ultrasound," "ultrasound in anesthesia," "airway management," "airway evaluation," and "difficult airway," a literature search was carried out utilizing databases like PubMed, MEDLINE, and Google Scholar. After screening articles based on their title and abstract, the whole text was examined to determine their eligibility. Peer-reviewed original studies, review articles, guidelines, or case reports centered on the use of ultrasound in airway management that were published after January 2005 were included. Publications irrelevant to airway management in anesthesia and those not available in English were not included. To help with the selection and evaluation of pertinent content, the authors also drew on their clinical expertise in airway ultrasonography.

Various studies have demonstrated that ultrasound parameters provide high sensitivity and specificity in predicting and managing difficult airways. The application of ultrasound parameters is effective in predicting difficult laryngoscopy or difficult tracheal intubation. The limitations of using ultrasound to predict difficult airways include operator dependency, lack of parameter standardization, anatomical variations, and pathological conditions. Ultrasound also has potential advantages in difficult airway management across different populations, guiding airway management and helping clinical decisions.

Ultrasound parameters and combinations have been associated with difficult laryngoscopy or difficult tracheal intubation prediction. Furthermore, combining these with clinical parameters can improve the management of difficult airways. Future advancements require multi-center research, artificial intelligence assistance, and technological innovations like three-dimensional ultrasound and elastography to drive clinical translation.