Effectiveness and validity of midsagittal tongue cross-sectional area and width measured by ultrasound to predict difficult airways

BACKGROUND: Increased tongue volume measured by ultrasound has been proven to be related to difficult airways. Tongue volume is an indirect parameter and is derived from multiplying the midsagittal tongue cross-sectional area (CSA) by the tongue width. However, few studies have focused on the ability of tongue CSA and tongue width to predict difficult airways. This study aimed to investigate the predictive value of tongue CSA and tongue width for predicting difficult laryngoscopy and difficult intubation. METHODS: This study included 244 adult patients who underwent general anesthesia and endotracheal intubation. Demographic variables were collected, and clinical airway assessments were performed. A curvilinear low-frequency probe was used for ultrasonography, and midsagittal tongue CSA and tongue width were measured before anesthesia. The laryngoscopic view and the difficulty of intubation was graded or scored after induction of anesthesia. RESULTS: A total of 230 patients were analyzed. Twenty-eight (12.2%) patients experienced difficult laryngoscopy and twelve (5.2%) patients experienced difficult intubation. Midsagittal tongue CSA evaluated by ultrasonography could help identify patients with difficult laryngoscopy (sensitivity 0.71, specificity 0.60) and patients with difficult intubation (sensitivity 0.50, specificity 0.97). And tongue width could help identify patients with difficult laryngoscopy (sensitivity 0.39, specificity 0.89). CONCLUSIONS: Ultrasonic measurement of midsagittal tongue CSA may be a valuable predictor of difficult laryngoscopy and difficult intubation. By contrast, tongue width measured by ultrasound may be a weak predictor of difficult laryngoscopy, but its predictive ability was questionable.

Automated summary

The study showed that using ultrasound to measure midsagittal tongue CSA can help predict the risk of difficult laryngoscopy and difficult intubation. Midsagittal tongue CSA has certain sensitivity and specificity in predicting difficult airways.