Fluid Overload in Patients Receiving Hemodialysis

Managing fluid overload in patients receiving hemodialysis is a major challenge. Patients experiencing fluid overload may develop hypervolemia. Vårin Vinje and colleagues in Demark conducted a study to test the hypothesis that patients on hemodialysis reaching dry weight could have undetected hypervolemia and low hemoglobin concentration due to hemodilution.

Results of the study were reported during a presentation at the ERA 60th Congress. The presentation was titled Intravascular Volumes and the Influence on Anemia in Patients Undergoing Maintenance Hemodialysis.

The overall study cohort included 22 patients on hemodialysis and 22 healthy controls. Using a carbon monoxide(CO)-rebreathing method, blood volume, plasma volume, red blood cell volume, and total hemoglobin mass were determined in hemodialysis patients reaching dry weight and in the control group. For validation purposes, blood volume measurements were also obtained by a dual-isotope labeling technique.

In 16 of the 22 hemodialysis patients, blood volume was higher than in the controls. In the hemodialysis group, the median blood volume was 89.3 mL/kg, compared with 79.9 m:/kg in the control group (P<.037). Median plasma volume was 54.7 mL/kg in the hemodialysis group compared with 44.0 mL/kg in the control group (P<.001).

Hemoglobin was lower in the hemodialysis group (P<.001). There was no difference in total hemoglobin mass between the two groups (P=.11). Changes in hemoglobin levels during and following dialysis were seen in the hemodialysis group. There was a correlation between blood volume measured by the CO-rebreathing test and the dual-isotope labelling technique in the control group (r=0.83; P=.015), but not in the hemodialysis group (r=0.25; P=.60)

“The hemodialysis group had increased blood volume at dry weight due to high plasma volume, indicating a hypervolemic state. The total hemoglobin mass was similar between hemodialysis patients and controls, unlike hemoglobin, which emphasizes that hemoglobin is an inaccurate marker of anemia among hemodialysis patients,” the researchers said.

Source: Vinje V, Bomholt T, Hornum M, et al. Intravascular volumes and the influence on anemia in patients undergoing maintenance hemodialysis. #3712. Abstract of a presentation at the European Renal Association 60th Congress; June 15-18, 2023; Milan, Italy.