Inferior Vena Cava Collapsibility Index: A Precise, Noninvasive Tool for Evaluation of Edema in Children with Nephrotic Syndrome

This study aimed to evaluate available volume status assessment tools in nephrotic syndrome (NS). Sixty children with INS were subdivided into hypovolemic and nonhypovolemic groups based on fractional excretion of sodium (FeNa%); all were studied for inferior vena cava collapsibility index (IVCCI), plasma atrial natriuretic peptide (ANP), and body composition monitor (BCM). Forty-four patients had nonhypovolemic and 16 had hypovolemic states. ANP did not difer between both groups. IVCCI was higher in hypovolemic group (p<0.001) with sensitivity 87.5% and specifcity 81.8% for hypovolemia detection, while BCM overhydration (BCM-OH) values were higher in nonhypovolemic group (p=0.04) with sensitivity=68.2% and specifcity=75% for detection of hypervolemia. FeNa% showed negative correlation with IVCCI (r= ?0.578, p<0.001) and positive correlation with BCM-OH (r=0.33, p=0.018), while FeNa% showed nonsignifcant correlation to ANP concentration. IVCCI is a reliable tool for evaluating volume status in NS and is superior to BCM.

Clinical usefulness of bioimpedance analysis for assessing volume status in patients receiving maintenance dialysis

Chronic volume overload is associated with left ventricular hypertrophy and high cardiovascular mortality in patients undergoing dialysis. Therefore, estimating body fluid status is important in these patients. However, most dry-weight assessments are still performed clinically, while attempts have been made to measure the volume status and dry weight of patients undergoing dialysis using bioimpedance analysis (BIA). BIA uses the electrical properties of the human body to alternate current flow and measures resistance values to estimate body water content and composition. BIA is divided into single-frequency BIA, multi-frequency BIA, and bioimpedance spectroscopy (BIS) according to the number of frequencies used, and into whole-body and segmental BIA according to whether or not the whole body is divided into segments. Extracellular water (ECW), intracellular water, and total body water (TBW) contents can be measured with BIA. Dry weight can be estimated by measuring the volume overload of the patient through the ECW/TBW and ECW-to-body weight ratios. Other estimation methods include the normovolemia/hypervolemia slope method, a resistance-reactance (RXc) graph, overhydration measurements using a body composition monitor, and calf BIS. In this review, we will examine the principles of BIA, introduce various volume status measurement methods, and identify the optimal method for patients undergoing dialysis.