Ultrasonography of the inferior vena cava (IVC) is a non-invasive technique widely employed to assess venous diameter and pulsatility, providing clinically relevant information on intravascular volume status and right atrial pressure (RAP). In routine clinical practice, this evaluation is based on non-standardized respiratory manoeuvres, such as the sniff test, which can limit measurement reproducibility and clinical reliability. This thesis aims to investigate IVC behaviour under controlled inspiratory conditions by combining real-time ultrasonography with simultaneous spirometric acquisition. The experimental setup integrates a custom 3D-printed spirometer with a mechanical airflow resistance designed for this study. The resistance was designed using Autodesk Fusion 360 and printed in PET plastic.