153 What are the Sonographic Baseline Measurements of the Inferior Vena Cava Diameter in Normovolemic Children?

Abstract

Children who present with dehydration or sepsis account for a significant number of pediatric emergency department visits. Accurate and rapid assessment of intravascular volume status is vital to providing appropriate management. Adult studies have demonstrated that point-of-care ultrasound of the inferior vena cava (IVC) can provide a rapid and objective measurement of a patient’s intravascular volume status. However, there is a lack of reference values for IVC diameter measurements in pediatric patients. Previous studies report the patient’s dry weight, IVC/body surface area ratio, IVC/aorta ratio, or collapsibility index as reference standards for pediatric IVC measurements. There are no definitive studies to date evaluating baseline IVC diameters in healthy children with presumed normal intravascular volume. To evaluate normative baseline sonographic measurements of the IVC diameter in healthy pediatric patients. This was a prospective observational study of a convenience sample of healthy patients between ages 0 and 22 presenting to a single institution pediatric emergency department. Exclusion criteria included abnormal vital signs, pregnancy, or illnesses thought to influence volume status (eg, diarrhea, vomiting, and asthma). Point-of-care ultrasound was performed on supine patients in the subxiphoid area using the phased array transducer of a SonoSite Edge machine. During quiet respiration, the maximal and minimal IVC diameters were measured in the sagittal plane distal to where the hepatic vein joins the IVC. As a second measurement, the maximal diameters of the IVC and aorta were measured in the transverse plane distal to the insertion of the left renal vein into the IVC. The institutional review board approved this study. From February 2013 through April 2014, sixty-three children (50.8% female, mean age 10.5 years) were enrolled. There were twenty children in each age group 2-7 years, 7-12 years, and 12-22 years. Children less than two years old had difficulty tolerating the examination and commonly presented with chief complaints and/or vital signs which met exclusion criteria. Consequently, fewer patients were enrolled in the less-than-two-years age group. The correlation between IVC and aorta diameters as a function of age were calculated using the Spearman’s rank correlation coefficient. The correlation coefficients were all statistically significant (P<.001): maximum IVC diameter sagittal plane (0.81), minimum IVC diameter sagittal plane (0.79), maximum IVC diameter transverse plane (0.79), maximum aorta diameter transverse plane (0.81). We present a pilot study of the sonographic measurements of the IVC diameter in normovolemic children. A statistically significant positive correlation was found between age and IVC diameter. Future studies should focus on multi-center enrollment, children in the youngest age group, and the development of normative growth curves of the IVC by age, sex, and body mass index.