Potential implications of subclinical hypervolemia, identified by a multiparametric approach, in causing left ventricular hypertrophy in clinically euvolemic children on dialysis: a prospective longitudinal pilot study

Abstract Background Fluid overload in children undergoing dialysis can lead to serious cardiac complications, i.e., left ventricular hypertrophy (LVH) and cardiac dysfunction. Studies investigating the cardiovascular effects of persistent subclinical hypervolemia—characterized by euvolemia at clinical assessment but hypervolemia at technical evaluation—are lacking. This pilot study explored the combined use of lung ultrasound (LUS), bioimpedance spectroscopy (BIS), and ultrasound assessment of the inferior vena cava collapsibility index (IVC-CI) to identify subclinical hypervolemia and investigated its cardiac impact. Methods In this longitudinal study, we recruited 23 children on chronic dialysis who underwent fluid status evaluation (physical examination, LUS, IVC-CI, BIS) every 2 months and echocardiography every 6 months. Results In clinically euvolemic patients, we observed a significant positive correlation between the interdialytic weight gain and the number of B-lines observed by LUS ( R = 0.2923, p < 0.001); similar results were obtained for the OH/ECW measured by BIS ( R = 0.4144, p < 0.001), while a negative correlation with IVC-CI ( R = − 0.2597, p = 0.019) was observed. Moreover, we identified a significant linear correlation between left ventricular mass index values and the average pre-dialysis systolic blood pressure measured over the preceding 6 months ( R 2 = 0.16, p = 0.002). Hospitalizations due to hypertensive crises (67% vs. 0%, p < 0.01) and the occurrence of LVH at the final follow-up (75% vs. 27%, p = 0.04) were notably more frequent in children with subclinical hypervolemia. Conclusion In clinically euvolemic children on dialysis, the combined use of LUS, BIS, and IVC-CI (multiparametric approach) effectively quantified subclinical hypervolemia, which was correlated with the risk of LVH.