Volume Assessment by Inferior Vena Cava Examination: Bedside Ultrasound Techniques and Practical Difficulties

Abstract

This article reviews the published literature that evaluated the reliability and accuracy of inferior vena cava (IVC) parameters measured by ultrasound for volume assessment, as well as those that described the potential change in these parameters induced by other factors. Several IVC parameters, including IVC diameter, phasic respiratory variation, and IVC/Aorta diameter ratio, were recommended for assessing volume status. They have been proven to be reliable, repeatable, and have good relationship with other indicators of volume status. However, the body size, respiratory status, anesthetics, and intra-thoracic and intra-abdominal pressure could affect their values. The reverse in IVC respiratory variation resulted from change in ventilation mode limits its application in the perioperative period. Ultrasound IVC measurements are reliable for volume assessment to facilitate clinical decision. The interpretation of the IVC parameters measured by ultrasound should be done by physicians aware of physiological principle and expected changes in IVC under certain circumstances.