The RXc Graph in Evaluating and Monitoring Fluid Balance in Patients with Liver Cirrhosis

Abstract

A recent study, using height-standardized resistance (R/H) and reactance (Xc/H) and assuming a bivariate distribution, has proposed the "RXc graph". We applied this new approach for patients with chronic liver disease in differentiating various degrees of fluid unbalance. Our data showed that a 95% confidence ellipse of patients with chronic hepatitis (CH) overlapped that of healthy control subjects (CONTR), while those of patients with liver cirrhosis (CIR), patients with cirrhosis and ascites (ACIR), and patients with cirrhosis, edemas, and ascites (AECIR) were clearly different for both genders. A progressively shorter mean impedance vector proportional to the stage of liver disease and to the degree of fluid unbalance was found. The lower half of the 50% tolerance ellipse for the healthy population proved to be a threshold for cirrhotics, while almost all the subjects with clinically detectable edema fell outside this limit. The RXc graph was shown to be useful in monitoring the treatment of fluid unbalance and for the immediate selection of patients in whom BIA can precisely assess body composition.

Bioelectric impedance vector distribution in peritoneal dialysis patients with different hydration status

“…The indifference of whole-body impedance to the abdominal drainage is a confirmatory result of other studies in CAPD patients and in patients with ascites [50][51][52] due to the 10% contribution of trunk versus 90% of limbs to the whole-body impedance [12,13]. The clinical usefulness of impedance in body composition analysis is based on this property that reflects the composition of homogeneous soft tissues of limbs (skin, muscles, and adipose tissue) and makes it negligible the heterogenous electric contribution of the trunk (skin, muscles, adipose tissue, mediastinum, lungs, pleural effusions, heart, big vessels, liver, pancreas, spleen, bladder, intestine, peritoneum, ascites, etc.).…”

“…In CAPD patients, the best estimation of peritoneal fluid volume (2100 mL, with bias 130 ± 300 for drained fluid to 190 ± 400 mL for infused fluid) was obtained with segmental BIA of the trunk using several arbitrary assumptions on body geometry (three different k values), fluid volume distribution (double for limbs versus trunk, with different powers of the impedance index) and changes in dialysate conductivity, and using smoothed mean values of the "extracellular R" (i.e., R value extrapolated to zero frequency from fitting a Cole-Cole model) [54]. In fact, removing the effect of these assumptions in volume estimation, extracellular R values changed little, within the measurement error range, up to 6 ohm after draining and filling [50,54].…”

Equivalence of information from single versus multiple frequency bioimpedance vector analysis in hemodialysis

“…From clinical validation studies of vector BIA in adults, including HD and peritoneal dialysis patients [40][41][42][43][44][45], vector displacements parallel to the major axis of tolerance ellipses indicate progressive changes in tissue hydration (dehydration with long vectors, and hyperhydration with short vectors). Consideration of changes of impedance measures, although forfeiting prediction of absolute volumes, allows determination of whether body fluid volumes have returned to those of a reference population group following dialysis, which is not possible with BIS.…”

A bioelectrical impedance phase angle measuring system for assessment of nutritional status

“…In patients suffering from malnutrition, PhA can reflect the early water shift from intracellular to extracellular space [7][8][9]. Thus, disease related malnutrition is associated with electrical changes, which can be measured through bioelectrical impedance analysis [10].…”