Correlation of Ultrasound-Based Hydration Assessment Measures with CVP and Clinical Hydration Status among Children Admitted to the PICU: A Prospective Observational Study

Abstract

Purpose This article assesses the correlation of respiratory variation in inferior vena cava (IVC) with central venous pressure (CVP) in children. Secondary objective was to evaluate IVC variability with clinical hydration status. Methods IVC variability was assessed at the subcostal (SC) and right lateral (RL) region, and collapsibility index (CI) (spontaneously breathing) and distensibility index (DI) (positive pressure) and IVC/aortic ratio were calculated. Partial correlations were calculated between CI/DI with CVP adjusting for body mass index and age. Sensitivity of CI and DI to predict clinical dehydration was calculated using receiver operating characteristic curves. Results A total of 145 ultrasounds were performed on 72 patients (41% positive pressure). Only RL CI in spontaneously breathing patients strongly correlated with CVP (r = –0.65, p < 0.001). A moderate correlation was observed between CI and DI from SC and RL regions (r's = 0.38 and 0.47). Among spontaneously breathing patients, a significant difference was observed in the SC CI based on hydration status. For patients on positive pressure, IVC/aortic ratio had a significant difference. SC CI had the highest area under the curve (0.82) to detect dehydration with 80% sensitivity/87% specificity for a cutoff of 40%. Conclusion SC CI is the most reliable measure to assess the hydration status of spontaneously breathing children, while the IVC/aortic ratio performs well for patients under positive pressure. RL CI has strong negative correlation with CVP in spontaneously breathing patients.