IVC to Aorta Ratio Tracks Fluid Response but Lacks Clinical Correlation

Managing pediatric shock requires rapid, precise volume expansion to restore tissue perfusion and prevent multiorgan failure [1, 2]. While fluid bolus therapy remains a cornerstone of initial stabilization, the physiological response to these interventions is often poorly understood and inconsistently measured in the acute setting [3]. Traditional clinical triggers like tachycardia and hypotension are frequently used to initiate treatment, yet their resolution does not always correlate with the restoration of adequate stroke volume [4, 5]. Point of care ultrasound has emerged as a tool for real-time hemodynamic monitoring, particularly through the assessment of dynamic preload indices (physiological markers used to predict whether a patient's cardiac output will increase in response to additional fluid) [6]. In a study of children aged 1 to 12 years with non-hemorrhagic shock, the ratio of the inferior vena cava to the aorta increased significantly from 0.79 to 0.91 following fluid administration (P < 0.001) [7]. However, the clinical utility of this vascular ratio may be limited, as the researchers observed only a weak positive correlation between these ultrasound changes and improvements in heart rate (r = 0.28) or shock index (r = 0.26) [7].