Inter-rater Reliability of Sonographic Measurements of the Inferior Vena Cava
Bedside ultrasound is emerging as a useful tool in the assessment of intravascular volume status by examining measurements of the inferior vena cava (IVC). Many previous studies do not fully describe their scanning protocol. The objective of this study was to evaluate which of three commonly reported IVC scanning methods demonstrates the best inter-rater reliability. Three physicians visualized the IVC in three common views and utilized M-mode to measure the maximal and minimal diameter during quiet respiration. Pairwise correlation coefficients were determined using Pearson product-moment correlation. The most reliable pair of measurements (inspiratory and expiratory) was found to be using the anterior midaxillary line longitudinal view with a Kappa value for both at 0.692. Imaging with the anterior midaxillary longitudinal approach using the liver as an acoustic window provides the best inter-rater reliability when measuring the IVC. Our findings demonstrate that IVC measurements differ based on anatomic location.