Inter-rater reliability of sonographic measurements of the inferior vena cava.

Background: 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.

Objectives: The objective of this study was to evaluate which of three commonly reported IVC scanning methods demonstrates the best inter-rater reliability.

Methods: 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.

Results: 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.

Conclusion: 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.