Randomized Trial on the Effects of Dialysate Potassium Concentration on Intradialytic Hypertension

Introduction

Intradialytic hypertension is not an uncommon condition during chronic hemodialysis. It is associated with unfavorable cardiovascular outcomes, including hospitalization and mortality. Several small studies have demonstrated the contradictory effects of different dialysate potassium concentrations on intradialytic blood pressure. This study is a randomized crossover trial aiming to evaluate the effects of different dialysate potassium concentrations on intradialytic hypertension.

Methods

A 24-week, 2-treatment, 4-sequence, multicenter, double-blinded, randomized, crossover study was conducted at Maharaj Nakorn Chiang Mai Hospital and Lampang Hospital in Thailand among stable patients receiving chronic hemodialysis who experienced intradialytic hypertension >30% of their sessions over the past 3 months. Each participant was randomly assigned to 1 of 4 treatment sequences. During each intervention period, patients were dialyzed with dialysate potassium of either 2 mmol/l (D-K2) or 3 mmol/l (D-K3) for 4 weeks according to their preassigned sequence, separated by a 2-week washout period. The primary outcome was the incidence of intradialytic hypertension.

Results

Forty eligible patients were recruited. The mean age was 61.4 ± 14.2 years and the mean systolic blood pressure (SBP) was 146.6 ± 11.2 mm Hg. Of the 40 patients, 95.5% had hypertension and their average number of antihypertensive drugs was 2.8 ± 1.9. A total of 1380 dialysis sessions were included in the analysis (695 sessions for D-K2 and 685 sessions for D-K3). The incidence of intradialytic hypertension was not significantly different between different dialysate potassium concentrations (D-K2 54.7% vs. D-K3 53.1%, P = 0.788). The changes in SBP, diastolic blood pressure (DBP), and mean arterial pressure (MAP) were not different between the 2 dialysate potassium groups.

Conclusion

Dialysate potassium concentration of 2 or 3 mmol/l did not affect the incidence of intradialytic hypertension in patients receiving chronic hemodialysis who frequently developed intradialytic hypertension.

Paradoxical Association Between Intradialytic Blood Pressure Change and Long-Term Mortality with Different Levels of Interdialytic Weight Gain

Background

A greater interdialytic weight gain (IDWG) implies a greater ultrafiltration rate, which might lead to hemodynamic instability and intradialytic blood pressure (BP) change in hemodialysis patients. However, current studies have not explicated the impact of IDWG on the association between intradialytic BP changes and prognosis, especially in patients without cardiac dysfunction and diabetes. In this study, we aimed to explore the relationship between absolute intradialytic BP changes and mortality with different IDWG levels.

Methods

A total of 204 hemodialysis patients (without cardiac dysfunction and diabetes) were included in this prospective observation study, with a mean follow-up of 55.32±20.99 months. Initially, we collected IDWG, IDWG% (percentages according to dry weight), and pre-/post-BPs of 36 consecutive dialysis sessions during three months enrollment. And the average value of them was defined as baseline value. Patients were divided into 3 cohorts according to IDWG% tertiles (<3.3%, 3.3%-4.6%, ≥4.6%). Comparisons between different tertiles were analyzed.

Results

Compared to the low IDWG% group (tertile 1, T1), patients of high IDWG% group (tertile 3, T3) were younger, had higher ultrafiltration rate, less residual kidney function, lower BMI and dry weight, longer dialysis vintage and higher N terminal pro B type natriuretic peptide levels (P<0.05). Correlations were found between IDWG% and intradialytic BP changes. Kaplan-Meier analysis and multivariate Cox regression model adjusted for demographic data, dialysis information and predialysis BPs indicated that greater absolute intradialytic BP changes were associated with worse prognosis in T1 group (P<0.05). While in T3 group, less absolute intradialytic BP changes were associated with higher mortality (P<0.05).

Conclusion

There is a paradoxical association between absolute intradialytic BP changes and long-term mortality with different IDWG levels. Both BP stability and volume balance are crucial to patients' prognosis.

Decreased pulse pressure during hemodialysis is associated with improved 6-month outcomes

Pulse pressure is a well established marker of vascular stiffness and is associated with increased mortality in hemodialysis patients. Here we sought to determine if a decrease in pulse pressure during hemodialysis was associated with improved outcomes using data from 438 hemodialysis patients enrolled in the 6-month Crit-Line Intradialytic Monitoring Benefit Study. The relationship between changes in pulse pressure during dialysis (2-week average) and the primary end point of non-access-related hospitalization and death were adjusted for demographics, comorbidities, medications, and laboratory variables. In the analyses that included both pre- and post-dialysis pulse pressure, higher pre-dialysis and lower post-dialysis pulse pressure were associated with a decreased hazard of the primary end point. Further, every 10 mm Hg decrease in pulse pressure during dialysis was associated with a 20% lower hazard of the primary end point. In separate models that included pulse pressure and the change in pulse pressure during dialysis, neither pre- nor post-dialysis pulse pressure were associated with the primary end point, but each 10 mm Hg decrease in pulse pressure during dialysis was associated with about a 20% lower hazard of the primary end point. Our study found that in prevalent dialysis subjects, a decrease in pulse pressure during dialysis was associated with improved outcomes. Further study is needed to identify how to control pulse pressure to improve outcomes.