The influence of low dialysate sodium and glucose concentration on volume distributions in body compartments after haemodialysis: a bioimpedance analysis study

Background. Despite the developments in haemodialysis, there are still some difficulties in maintaining the haemodynamic stability. Bioimpedance analysis (BIA) has been proposed for the estimation of dry weight in haemodialysis patients. We aimed to investigate the effects of dialysate sodium and glucose contents on volume distribution in body compartments after haemodialysis by using BIA, a sensitive and reliable method. Methods. Seventeen chronic haemodialysis patients [11 males, 6 females, mean age: 36.9 (18-64) years] were included in the study. Patients were evaluated in three periods. The patients (period 1-P1) underwent haemodialysis with dialysate of 200 mg/dL glucose and 140 mmol/dL sodium for 4.5 h in the middle session of the first week. At the beginning and the end of the session, haematocrit, vital parameters (blood pressure, pulse), ultrafiltrated volume, plasma osmolarity and plasma renin activity were recorded. Also multi-frequency bioelectric impedance analyses (Bodystat (R) Quadscan 4000) were applied to all patients at 5, 50, 100 and 200 kHz, including the impedance index (Z200/Z5). In the second midweek session the same procedure was repeated with same glucose concentration and 135 mmol/dL sodium including dialysate (period 2-P2), and in the third week, it was performed with a dialysate that included 140 mmol/dL sodium and no glucose (period 3-P3). Results. The change of the ratio of the intracellular volume to total body weight (ICV/TBW) at the beginning and the end of the session was same in all periods. However, there were significant differences in the change (after/before session) ratio for the extracellular volume/total body weight (ECV/TBW) in P2 compared to other periods (P values for P1-P2: < 0.001 and P2-P3: 0.007). Likewise, the same was observed in the changes of impedance (P values for P1-P2: 0.08, P1-P3: 0.44 and P2-P3: 0.063). There was a significant increase of hypotensive events in P2 against the other periods (P = 0.001). Conclusion. Decreasing dialysate sodium concentration results in important haemodynamic changes but the lack of glucose in dialysate does not result in any changes in haemodynamic and inflammatory parameters. The changes in bioimpedance parameters are parallel to haemodynamic changes in the haemodialysis patients.