#3712 INTRAVASCULAR VOLUMES AND THE INFLUENCE ON ANAEMIA IN PATIENTS UNDERGOING MAINTENANCE HAEMODIALYSIS

Abstract

Abstract Background and Aims Fluid overload is a major challenge in haemodialysis (HD) patients and might cause hypervolaemia. We speculated that HD patients reaching dry weight could have undetected hypervolaemia and low haemoglobin concentration (Hb) due to haemodilution. Method The study included HD patients (n = 22) and matched healthy controls (n = 22). Blood volume, plasma volume, red blood cell volume, and total haemoglobin mass (Hb mass) were determined using a carbon monoxide (CO)-rebreathing method in HD patients reaching dry weight and controls. Blood volume measurements were also obtained by a dual-isotope labelling technique in a subgroup for validation purposes. Results Blood volume was higher in 16 out of the 22 HD patients compared to controls. In the HD group, the median blood volume was 89.3 mL/kg (interquartile range (IQR) 76.7–95.4 mL/kg) and was higher than in the control group (79.9 mL/kg (IQR 70.4–88.0 mL/kg); P < 0.037) (Table 1). The median plasma volume was 54.7 mL/kg (IQR 47.1–61.0 mL/kg) and 44.0 mL/kg (IQR 38.7–49.5 mL/kg) in the HD and control groups, respectively (P < 0.001). Hb was lower in HD patients (P<0.001), whereas no difference in total Hb mass was observed between groups (P = 0.11). Changes in Hb levels during and after dialysis were observed in the HD group and is shown in Fig. 1. A correlation was found between blood volume measured by the CO-rebreathing test and the dual-isotope labelling technique in the control group (r = 0.83, P = 0.015), but not the HD group (r = 0.25, P = 0.60). Conclusion The HD group had increased blood volume at dry weight due to high plasma volume, indicating a hypervolaemic state. The total Hb mass was similar between HD patients and controls, unlike Hb, which emphasizes that Hb is an inaccurate marker of anaemia among HD patients.