Bioelectrical Impedance Analysis (BIA) to Estimate Body Composition Measurement: High Variability Due to Presence of Ascites

Abstract

Purpose: Body composition assessment can be utilized for the nutrition evaluation of protein calorie malnutrition in patients with end stage liver disease (ESLD). Bioelectric impedance analysis (BIA) is a widely utilized method to assess total body composition. The Bodystat® 4000 (Bodystat Limited, UK) machine has been introduced for body composition analysis. By affecting the signal conduction, fluid retention such as ascites may pose difficulties in assessing the degree of malnutrition and estimation of nutrition support by BIA. There is limited data on the effect of fluid retention/ascites on the accuracy of body composition analysis in patients with ESLD. Therefore, we aim to assess the accuracy in the BIA before and after large volume abdominal paracentesis (LVP) in patients with ESLD. Methods: A prospective cohort study in patients with ESLD with ascites was performed at our institution. Adult (≥18 years) patients with ESLD who were scheduled to receive LVP were included in our study. Patients with low-volume paracentesis (<2 liters) and patients who cannot give informed consent were excluded from the study analysis. The total volume of paracentesis fluid, patient's height and weight (before and after LVP) were recorded. A Bodystat® 4000 machine was utilized to obtain BIA measurements (at five Ohm, 50 Ohm, 100 Ohm, and 200 Ohm). The machine estimated the total body composition components: total body fat, lean body mass, dry body weight, and body cell mass, total body fluid, extracellular fluid and intracellular fluid. We obtained these measurements just before and immediately after LVP. Measurements after LVP were obtained using new weight after paracentesis. We compared these measurements using paired t test (p≤0.05). Results: A total of 25 patients with ESLD were recruited. After excluding four patients with low-volume paracentesis volume (<2 liters), a total 21 patients were included in our final analysis. The mean age of the patients was 61.4 years (71% male). The average amount of abdominal paracentesis was 6.8 liters (range 2 - 13 liters). The results of the BIA and total body composition measurements before and immediately after LVP are shown in table.Table: Table. Comparison of total body composition components before and after LVP using paired two tailed t testConclusion: Our study found significant variability in all body compartments measured by BIA using Bodystat® 4000 machine in ESLD patients undergoing LVP. The accuracy of body composition measurements using a Bodystat® 4000 machine is not reliable in patients with ESLD patients with ascites.