Bioelectrical impedance analysis for assessing hydration status in patients undergoing maintenance hemodialysis.

Abstract

Background: Adequate hydration status is a concern in patients receiving hemodialysis, as fluid overload increases the risk of complications and mortality. Fluid overload in this population is associated with complications, including arterial hypertension, intradialytic hypotension, pulmonary and peripheral edema, cardiovascular events, reduced body mass index, malnutrition, and increased mortality. Several methodologies have been proposed to evaluate hydration status in hemodialysis patients using indices derived from Bioelectrical impedance analysis parameters.

Aim: To assess the hydration status of patients receiving hemodialysis using different indices.

Methods: Patients receiving hemodialysis for at least 3 months were included. Hydration status was evaluated before and after the hemodialysis session. The data provided by bioelectrical impedance analysis were total body water (TBW), intracellular water, and extracellular water (ECW). Fluid overload [overhydration (OH)] was calculated. Hydration status was classified according to the three indices: OH, OH/ECW, and ECW/body weight. Interdialytic weight gain (IDWG) and blood pressure (BP) were collected. N-terminal pro-brain natriuretic peptide were measured before and after the hemodialysis.

Results: A total of 54 patients were evaluated, with mean age of 57.6 ± 13.1 years, 59.3% male. Before hemodialysis session, 23 patients were classified as having fluid overload, identified by at least one of the indices. IDWG and ECW showed significant positive correlation with all evaluated indices. BP, TBW, and intracellular water correlated only with the OH and OH/ECW indices. After hemodialysis session, 5 patients were identified with fluid overload by the OH and ECW/body weight indices. ECW was the only parameter that showed correlation with all indices. N-terminal pro-brain natriuretic peptide correlated with the OH and ECW/body weight indices. BP, IDWG, and TBW remained correlated with OH and OH/ECW.

Conclusion: The OH index identified a greater number of patients with fluid overload and showed better correlation with hydration parameters provided by the bioelectrical impedance analysis.