Baseline Diameter of the Inferior Vena Cava Measured with Sonography in Euvolemic Children and its Relationship to Somatic Variables.

PURPOSE  To determine normative data for the inferior vena cava (VCI) diameter in euvolemic children and its correlation with different somatic parameters in a pediatric population at one center in Europe. MATERIALS AND METHODS  This prospective observational study enrolled healthy children aged 4 weeks to 18y that visited our outpatient clinic. Weight, height, body surface area, and age were recorded. The children were grouped according to weight, as follows (80 children/group): < 10 kg, 10-19.9 kg, 20-29.9 kg, 30-59.9 kg, and 60-90 kg. Children were placed in a supine position and, during quiet respiration, the maximum and minimum VCI diameters were measured with M-mode ultrasonography. The collapsibility index (CI) was also automatically calculated for each subject: CI = [VCI maximum (expiratory) diameter - VCI minimum (inspiratory) diameter]/VCI maximum (expiratory) diameter. RESULTS  From May 2016 through November 2018 we retrieved data for 415 children that underwent VCI diameter evaluations. 400 children were included (mean age: 7.8y ± 5.8, mean weight: 32 kg ± 24.4, 46 % girls). The VCImax and the VCImin were significantly correlated with age (r = 0.867, p < 0.001, r = 0.797, p < 0.001), height (r = 0.840, p < 0.001, r = 0.772, p < 0.001), weight (r = 0.858, p < 0.001, r = 0.809, p < 0.001), and BSA (r = 0.878, p < 0.001, r = 0.817, p < 0.001). Correlations between the CI and age, weight, height, and BSA were not statistically significant. CONCLUSION  This prospective study provided reference values for sonographic measurements of VCI diameters in euvolemic children and might greatly assist in assessing fluid status in sick children.