Bioelectrical impedance analysis in the assessment of hydration status in peritoneal dialysis patients

Abstract

Objective: Assessment of fluid status in chronic peritoneal dialysis (PD) patients is complex. Clinical evaluation based solely on body weight, blood pressure, volume of ultrafiltration (UF) and peripheral edema is insufficient. A non-invasive test, bioelectrical impedance analysis (BIA) might be of potential benefit.

Aim: To test whether BIA correlates with other ancillary markers of extracellular fluid volume, namely B-type natriuretic peptide (BNP), residual renal function (RRF) and UF, and whether BIA provides complementary information in categorizing PD patients vis-à-vis hydration status.

Methods: A cross-sectional study of 61 out-patients on chronic PD. Single-frequency BIA measurements of resistance/height were divided into tertiles (lowest: <253 Ω/m; middle: >253 Ω/m and <316 Ω/m; highest: >316 Ω/m).

Results: Compared to patients in the highest tertile of BIA (least fluid), patients in the lowest tertile (most fluid) had highest BNP, RRF and UF (93.5 vs. 55.0 pg/ml, p = 0.029; 850 vs. 300 ml/day, p = 0.05; and 1.75 vs. 1.21 l/day, p = 0.023, respectively).

Conclusions: BIA tertiles categorized PD patients who differed in BNP, RRF and UF in a stepwise pattern, suggesting BIA may better inform hydration status, and serve as an additional clinical tool in management of chronic PD patients.