Reproducibility and inter-observer variability of the internal jugular vein ultrasonographic assessment: a multicenter cross-sectional study

This study evaluates inter-observer variability in measuring internal jugular vein (IJV) ultrasonographic parameters using images obtained from medical ward patients. A cross-sectional study was conducted across 4 Italian hospitals. After brief training, 8 expert sonographers and 11 novices measured at the supraclavicular, cricoid, and submandibular levels, the anteroposterior expiratory maximum diameter (AP-IJV max), maximum cross-sectional area (CSA-IJV max), aspect ratio (AP-IJV max to latero-lateral diameter), and collapsibility index (IJV-c) on 60 IJV ultrasound images from 10 patients. Inter-observer reliability was assessed using the intraclass correlation coefficient. No significant differences were observed between experts and novices for AP-IJV max, CSA-IJV max, or aspect ratio across the different views. The lowest inter-examiner variability was found for AP-IJV max and CSA-IJV max at the supraclavicular level. Aspect ratio showed moderate reliability among experts but poor reproducibility among novices. The IJV-c demonstrated the highest inter-examiner variability in both groups. To our knowledge, this is the first multicenter study aimed at evaluating the method's reliability of different non-invasive acoustic measurements and windows to identify IJV dimensions better to use mainly in case of hypovolemia or fluid challenge. The AP-IJV max and the CSA-IJV max measurements showed excellent inter-observer reproducibility, suggesting the use of point-of-care ultrasound protocols for non-invasive volume assessment, particularly at the neck’s base or cricoid level.