Haemodialysis and haemodiafiltration lead to similar changes in vascular stiffness during treatment

Unveiling the Clinical Benefits of High-Volume Hemodiafiltration: Optimizing the Removal of Medium-Weight Uremic Toxins and Beyond

Dialysis treatment has improved the survival of patients with kidney failure. However, the hospitalization and mortality rates remain alarmingly high, primarily due to incomplete uremic toxin elimination. High-volume hemodiafiltration (HDF) has emerged as a promising approach that significantly improves patient outcomes by effectively eliminating medium and large uremic toxins, which explains its increasing adoption, particularly in Europe and Japan. Interest in this therapy has grown following the findings of the recently published CONVINCE study, as well as the need to understand the mechanisms behind the benefits. This comprehensive review aims to enhance the scientific understanding by explaining the underlying physiological mechanisms that contribute to the positive effects of HDF in terms of short-term benefits, like hemodynamic tolerance and cardiovascular disease. Additionally, it explores the rationale behind the medium-term clinical benefits, including phosphorus removal, the modulation of inflammation and oxidative stress, anemia management, immune response modulation, nutritional effects, the mitigation of bone disorders, neuropathy relief, and amyloidosis reduction. This review also analyzes the impact of HDF on patient-reported outcomes and mortality. Considering the importance of applying personalized uremic toxin removal strategies tailored to the unique needs of each patient, high-volume HDF appears to be the most effective treatment to date for patients with renal failure. This justifies the need to prioritize its application in clinical practice, initially focusing on the groups with the greatest potential benefits and subsequently extending its use to a larger number of patients.

Clinical performance, intermediate and long-term outcomes of high-volume hemodiafiltration in patients with kidney failure

Hemodiafiltration (HDF), in which both convective and diffusion methods are combined, yields an increased overall solute clearance compared with hemodialysis (HD), specifically for medium and larger molecular weight uremic toxins. Due to uncertainty in the treatment effects, the nephrology community still perceives the implementation of HDF and the achievement of high convective volume as complex. In this article, we review practical aspects of the implementation of HDF that can effectively deliver a high-volume HDF therapy and assure clinical performance to most patients. We also present an overview of the impact of high-volume HDF (compared to HD) on a series of relevant biochemical, patient-reported, and clinical outcomes, including uremic toxin removal, phosphate, Inflammation and oxidative stress, hemodynamic stability, cardiac outcomes, nutritional effects, health-related quality of life, morbidity, and mortality.

Does Pulse Wave Velocity Increase Over Time in Hemodialysis Patients?

OBJECTIVES

Arterial stiffness, measured by pulse wave velocity (PWV), is reported to be increased in hemodialysis (HD) patients and increases cardiovascular mortality. Previous studies have reported an association between extracellular water (ECW) and PWV. We wished to review whether PWV increases over time and whether this is associated with ECW.

METHODS

We reviewed repeat aortic PWV measurements using an oscillograph method along with corresponding ECW measured by multifrequency bioimpedance in HD patients a minimum of 5 years apart.

RESULTS

Twenty-four patients (16 [66.7%] male and 11 [45.8%] diabetic, mean age 61.7 ± 15.2 years) had PWV and ECW initially measured after 46 (26-124) months of HD and then after 112 (97-202) months. Overall, there was no change in PWV or ECW (9.4 ± 2.2 vs. 8.1 ± 2.5 cm/s; 14.7 ± 2.5 vs. 15.2 ± 2.9 L, respectively), whereas the ECW/total body water ratio increased (0.399 ± 0.015 vs. 0.408 ± 0.021, p < 0.05). We found no association between changes in PWV and ECW (r = -0.05, p = 0.84), whereas there was an association with the change in peri-dialytic systolic blood pressure (SBP) (r = 0.59, p = 0.007).

CONCLUSION

In our small observational study, there was no overall change in PWV, after 5 years of HD, with PWV increasing in 50% and falling in 50%. Changes in PWV were not associated with changes in ECW but were associated with changes in peri-dialytic SBP. Our study demonstrates that PWV does not increase in all HD patients with time, and interventional studies are required to determine whether targeted blood pressure control reduces PWV in HD patients.

The association between peri-dialytic pulse wave velocity measurements and hemodialysis patient mortality

INTRODUCTION

Arterial stiffness in the general population is an independent prognostic factor for cardiovascular mortality, and can be measured noninvasively by pulse wave velocity (PWV). PWV is increased in hemodialysis (HD) patients, but the prognostic additional value remains debatable, with variable results reported. We wished to review whether increased PWV was associated with mortality in our HD patients.

METHODS

Aortic pulse wave velocity (PWVao) was measured peridialytic using an oscillograph technique (Arteriograph TensioMed, Hungary), in a cohort of HD patients in 2012.

FINDINGS

Three hundred and eighty-three HD patients, 238 (62.1%) male, median age 67.7 (54.2-78.0) years, 163 (42.6%) diabetic, Charlson comorbidity score 7 (5-9) and PWVao 8.9 (7.4-11.2) m/s were studied. Two hundred and twenty-nine deaths occurred during a median 61.1-month follow-up. PWVao was associated with all-cause mortality in unadjusted models (odds ratio [OR] for PWVao as a continuous variable 1.084, 95% confidence limits [CL] 1.046-1.124), P < 0.001, and for patients with PWVao>10 m/s (OR 1.61, CL 1.240-2.098, P < 0.001), but not after adjusting for clinical confounders (OR 1.024, CL 0.987-1.063, P = 0.208), whereas age (OR 1.049, CL 1.038-1.060, P < 0.001), and Charlson comorbidity (OR 1.131, CL1.065-1.201, P < 0.001) remained significantly associated with mortality.

DISCUSSION

Although our HD patients with an increased PWVao had greater all-cause mortality, after adjustment for age and comorbidity, the prognostic value of a single PWVao measurement was no longer an independent prognostic factor for mortality. Future studies are required to determine whether changes in PWV offer additional prognostic value for HD patients.

Chronic Kidney Disease and Pulse Wave Velocity: A Narrative Review

Chronic kidney disease (CKD) is associated with excess cardiovascular mortality, resulting from both traditional and nontraditional, CKD-specific, cardiovascular risk factors. Nontraditional risk factors include the entity Chronic Kidney Disease-Mineral and Bone Disorder (CKD-MBD) which is characterised by disorders of bone and mineral metabolism, including biochemical abnormalities of hyperphosphatemia and hyperparathyroidism, renal osteodystrophy, and vascular calcification. Increased arterial stiffness in the CKD population can be attributed amongst other influences to progression of vascular calcification, with significant resultant contribution to the cardiovascular disease burden. Pulse wave velocity (PWV) measured over the carotid-femoral arterial segments is the noninvasive gold-standard technique for measurement of aortic stiffness and has been suggested as a surrogate cardiovascular end-point. A PWV value of 10 m/s or greater has been recommended as a suitable cut-off for an increased risk of cardiovascular mortality. CKD is a risk factor for an excessive rate of increase in aortic stiffness, reflected by increases in PWV, and increased aortic PWV in CKD shows faster progression than for individuals with normal kidney function. Patients with varying stages of CKD, as well as those on dialysis or with a kidney transplant, have different biological milieu which influence aortic stiffness and associated changes in PWV. This review discusses the pathophysiology of arterial stiffness with CKD and outlines the literature on PWV across the spectrum of CKD, highlighting that determination of arterial stiffness using aortic PWV can be a useful diagnostic and prognostic tool for assessing cardiovascular disease in the CKD population.