The inferior vena cava
Interrogation of the inferior vena cava (IVC) plays an important role in the performance of critical care echocardiography and provides insight into the systemic hemodynamics of patients with critical illness. In conjunction with clinical examination, IVC assessment can be used as a surrogate marker of right atrial pressure and fluid responsiveness (1–3). Non-invasive measurements of IVC size and collapsibility may allow one to grossly infer central venous pressure (1–3). Sonographic capture of the IVC can be performed readily with good inter-rater reliability after a brief training period (4).