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.

Assessing Extracellular Volume in Hemodialysis Patients Using Intradialytic Blood Pressure Slopes

“…However, our study includes objective measurements of ECV using the BIS equipment to establish this relationship along a more continuous spectrum of volume states. Our findings also significantly expand on 3 recent case-control studies, which showed that patients with intradialytic BP increases had more volume overload based on BIS measurements than those with intradialytic BP decreases [7, 8, 26]. However, our study establishes that the repeated measurements included in the IBPS provide superior information than just the change in systolic BP from pre- to post-HD and that one can predict the relative degree of ECV overload based on the IBPS.…”

“…Intradialytic blood pressure (BP) patterns have recently been linked to the degree of ECV overload [7, 8] with patients exhibiting intradialytic hypertension having higher ratios of ECV/TBW compared to patients with BP decreases. These findings require deeper investigation because (1) only 15% of hemodialysis patients regularly experience intradialytic hypertension [9, 10] and (2) it is uncertain if this relationship extends across a continuous spectrum of intradialytic BP changes.…”

Intradialysis Hypertension in End-Stage Renal Disease Patients

“…19 When patients were stratified into 3 categories according to the type of intradialytic hemodynamic response, those with intradialytic rise in SBP >10 mm Hg had higher extracellular water/total body water ratio predialysis, lower weight loss within dialysis, and higher extracellular water/total body water ratio post dialysis than those with SBP fall or stable SBP during dialysis. 19 Notably, although volume expansion is suggested as a major pathogenic mechanism of intradialytic hypertension, not all patients presenting this phenomenon are volume overloaded.…”

Severe hypertension after initiation of rifapentine/isoniazid for latent tuberculosis in renal transplant candidates

“…We were unable to completely exclude the influence of other factors such as volume overload, sympathetic hyperactivity or erythropoietin treatment, which can cause uncontrolled hypertension in patients with CKD [5][6][7]. Our study is limited by the small number of cases, retrospective design, and lack of control group.…”