Interobserver Agreement of Inferior Vena Cava Ultrasound Collapse Duration and Correlated Outcomes in Children with Dehydration

Objective: Dehydration is a common concern in children presenting to pediatric emergency departments and other acute care settings. Ultrasound (US) of the inferior vena cava (IVC) may be a fast, noninvasive tool to gauge volume status, but its utility is unclear. Our objectives were to determine the interobserver agreement of IVC collapse and collapse duration, then correlate IVC collapse with the outcome of intravenous (IV) versus oral (PO) rehydration. Methods: We conducted a prospective study by enrolling patients 0 to 21 years old with emesis requiring ondansetron or diarrhea requiring IV hydration. Clinical operators interpreted US examinations in real time to determine whether the IVC was collapsed. Two blinded reviewers interpreted the US videos to determine IVC collapse and collapse duration. Cohen's kappa(k) was calculated for reviewer-reviewer and reviewer-operator agreement. Primary outcomes were PO versus IV rehydration, and admitted versus discharged. Results: One hundred twelve patients were enrolled, and 102 had complete data for analysis. The mean age was 7.2 years with 51% female. Twenty-nine patients received IV hydration. The reviewer-operator agreement for IVC collapse was k = 0.57 (95% confidence interval [CI], 0.38-0.75) and interreviewer agreement was k = 0.93 (95% CI, 0.83-1.0). The interreviewer agreement for collapse duration was k = 0.66 (95% CI, 0.51-0.82). All patients with noncollapsed IVCs tolerated PO hydration. The likelihood of receiving IV hydration was correlated with the duration of IVC collapse (P = 0.034). Conclusions: Based on a novel dynamic measure of IVC collapse duration, children with increasing duration of IVC collapse correlated positively with the need for IV rehydration. Noncollapsing IVCs on US were associated with successful PO rehydration without need for IV fluids or emergency department revisits.