Improved Repeatability of the Estimation of Pulsatility of Inferior Vena Cava

The inferior vena cava (IVC) shows variations of cross section over time (pulsatility) induced by different stimulations (e.g., breathing and heartbeats). Pulsatility is affected by patients' volume status and can be investigated by ultrasound (US) measurements. An index of IVC pulsatility based on US visualization and called caval index (CI) was proposed as a non-invasive indirect measurement of the volume status. However, its estimation is not standardized, operator dependent and affected by movements of the vein and non-uniform pulsatility. We introduced a software that processes B-mode US video clips to track IVC movements and estimate CI on an entire portion of the vein. This method is here compared to the standard approach in terms of repeatability of the estimated CI, reporting on the variability over different respiratory cycles, longitudinal IVC sections and intra-/inter-observers. Our method allows to reduce the variability of CI assessment, making a step toward its standardization.