Increased postdialysis systolic blood pressure is associated with extracellular overhydration in hemodialysis outpatients

Abstract

Recently, intradialytic hypertension was reported to be associated with increased mortality for hemodialysis patients. To determine whether volume status plays a role in dialysis-associated hypertension, we prospectively audited 531 patients that had volume assessments measured by multiple-frequency bioelectrical impedance during their midweek dialysis session. Mean pre- and postdialysis weights were 73.2 vs 71.7 kg, and systolic blood pressures (SBPs) 140.5 vs. 130.3 mm Hg, respectively. Patients were divided into groups based on a fall in SBP of 20 mm Hg or more (32%), an increased SBP of 10 mm Hg or more (18%), and a stable group (50%). There were no differences in patient demographics, dialysis prescriptions, predialysis weight, total body (TBW), and extracellular (ECW) and intracellular water (ICW). However, the change in weight was significantly less in the increased blood pressure group (1.01 kg vs. stable 1.65, and 1.7 hypotensive). The ratio of ECW to TBW was significantly higher in the increased blood pressure group, particularly post dialysis (39.1 vs. stable 38.7% and fall in blood pressure group 38.7%). ECW overhydration was significantly greater in the increased blood pressure group post dialysis (0.7 (0.17 to 1.1) vs. stable 0.39 (-0.2 to 0.95) and fall in blood pressure group 0.38 (-0.19 to 0.86) liter). We found that patients who had increased blood pressure post dialysis had greater hydration status, particularly ECW. Thus, patients who increase their blood pressure post dialysis should have review of target weight, consideration of lowering the post-dialysis weight, and may benefit from increasing dialysis session time or frequency.