Predicting difficult laryngoscopy using ultrasound measurement of distance from skin to epiglottis.

BACKGROUND: Unpredicted difficult intubation can have severe consequences, and it is a significant source of morbidity and mortality. Although recent studies indicate that specific ultrasonography (US) measurements may be predictors of difficult laryngoscopy, their use is still limited, and its quantification is missing. The purpose of this prospective observational study is to evaluate the use of US-measured distance from skin to epiglottis (DSE) for difficult laryngoscopy prediction.

METHODS: In a double-blind study, standard preintubation, screening tests, and DSE were obtained from 74 adult patients requiring endotracheal intubation. The relationship between difficult laryngoscopy and DSE was evaluated using a t test. A comparative analysis of its predictive performance with common clinical preintubation screening tests was performed using bootstrapping.

RESULTS: We found that increasing DSE is strongly associated with difficult laryngoscopy (P < .001, 2-sided t test). We showed that a cutoff value of 27.5 mm was able to predict difficult laryngoscopy with an accuracy of 74.3%, a sensitivity of 64.7%, and a specificity of 77.1%.

CONCLUSIONS: Our work demonstrates that the DSE can be effectively used to predict difficult laryngoscopy. Moreover, combining DSE with the modified Mallampati score in a decision tree significantly improves the predictive power over either test alone.