Influence of plasma volume status on blood pressure in patients on maintenance hemodialysis

Abstract

AbstractBackground.Hypervolemia is considered a major pathogenic factor for hypertension in patients receiving hemodialysis (HD). We examined the effect of intradialytic changes in body weight and plasma volume on blood pressure (BP) in a cohort of chronic HD patients.Patients and Methods.One hundred chronic, stable HD patients were the subjects of the present study. They were divided into 2 groups according to their pre‐dialysis BP. Each group was examined for potential significant correlations of intradialytic changes in body weight and plasma volume with pre‐ and post‐dialysis blood pressure values. The intradialytic decrease in plasma volume was calculated from pre‐dialysis and post‐dialysis total plasma protein concentrations and was expressed as a percentage of the plasma volume at the beginning of the hemodialysis session.Results.In group A (hypertensive group, n=43), post‐dialysis systolic and diastolic blood pressure (SBP and DBP) were significantly lower than pre‐dialysis values (p < 0.05). The mean intradialytic reduction in body weight was 2.97±1.33 kg, and the mean intradialytic decrease in plasma volume was 13.6%±8.23%. There was no significant correlation between intradialytic change in either SBP or DBP and intradialytic change in body weight or plasma volume. In group B (normotensive group, n=57), post‐dialysis SBP and DBP were significantly lower than pre‐dialysis levels (p < 0.05). The mean intradialytic reduction in body weight was 2.64±1.07 kg, and the mean intradialytic decrease in plasma volume was 13.4%±7.73%. A positive significant correlation was recorded between intradialytic change in SBP and change in body weight in normotensive group. Multiple regression analysis revealed that for the study patients as a whole, pre‐dialysis SBP, intradialytic change in SBP, pre‐dialysis DBP, and post‐dialysis SBP were not significantly correlated with intradialytic changes in plasma volume and body weight.Conclusions.Our findings clearly indicate that intradialytic change in plasma volume does not influence either pre‐dialysis or post‐dialysis blood pressure. From our results, we conclude that assessment of intradialytic change in plasma volume is not useful for evaluating the hydration status of HD patients in clinical practice.