Accuracy of ultrasound-guided marking of the cricothyroid membrane before simulated failed intubation.

BACKGROUND: Interest in the use of dynamic ultrasound (US) for cricothyrotomy has sparked a debate regarding its applicability in a crash airway situation. Ultrasound-guided marking of the cricothyroid membrane (CTM) as a preintubation procedure may be better than the dynamic method. No prior study has evaluated the accuracy of using US to premark the CTM before attempted intubation.

OBJECTIVES: To determine the feasibility of US-guided marking of the CTM before attempted simulated intubation so that this marking may be used as the location for the initial incision after failed intubation.

METHODS: Resident and attending physicians participated. Ultrasound was used to identify and mark the CTM with an invisible pen. Failed intubation was simulated, and the same operator then identified the CTM with US and marked the location with a black pen. The difference in the preintervention and postintervention markings was measured in millimeters. The length of the CTM was also measured as a reference.

RESULTS: Twenty-three models and operators were used for data collection. The average CTM sagittal length was 13.9 mm (95% confidence interval [CI], 13.4-14.4). The average sagittal and axial differences before and after simulated intubation were found to be 0.91 mm (95% CI, 0.35-1.47) and 1.04 mm (95% CI, 0.38-1.7), respectively. The sagittal variability is 1/15 the total length of the CTM.

CONCLUSIONS: Ultrasound marking of the CTM of healthy volunteers before simulated intubation accurately identifies the CTM after neck manipulation expected during a failed intubation. Further research is indicated to determine the clinical applicability of this model.