Passive leg raising (PLR) maneuver is a non-invasive and effective technique to assess fluid responsiveness, particularly useful in monitoring cardiac preload. Unlike intravenous administration, which involves direct fluid introduction and potential associated risks, PLR allows immediate assessment by simulating the effect of a fluid load without actual infusion. In this study, thirteen healthy subjects (5 men and 8 women, mean age 27 ± 9.5 years) underwent two consecutive PLR maneuvers. Each maneuver was assessed through a sequence of three events: pre-maneuver (baseline), during PLR and immediately post-maneuver. The segmentation of the inferior vena cava (IVC) has been performed using a software developed by Viper s.r.l., which included the use of a GUI in MATLAB for data analysis.