Bioimpedance for assessing volume status in children with nephrotic syndrome

The effectiveness of assessing volume load via bioimpedance in pediatric patients with nephrotic syndrome (NS) was investigated.

Patients with NS (n = 34) were compared with healthy controls (n = 20). The inferior vena cava index and inferior vena cava collapsibility index (IVCCI) scores were determined for all subjects. Bioimpedance measurements were used to directly determine volume load. Clinical findings, relative fluid load, and echocardiographic measurements were determined and compared with bioimpedance in calculating volume load.

The sensitivity and specificity of bioimpedance in determining volume load were found to be 65% and 90%, respectively. IVCCI was lower in NS patients than in controls. There were also significant differences in IVCCI values between patients with localized and generalized edema. Relative fluid load was higher in NS patients with generalized edema as opposed to patients with localized edema. For calculating volume load, the sensitivity of bioimpedance, clinical findings, and echocardiographic measurements was 87%, 95%, and 83%, respectively, whereas the specificity of determining volume load by bioimpedance, clinical findings, and echocardiographic measurements was 50%, 10%, and 80%, respectively.

Our data suggest that bioimpedance may be superior to echocardiography in determining volume load in children with NS, because it is cost-effective, reliable, and relatively simple to perform.