Effect of reuse of polysulfone membrane on oxidative stress during hemodialysis

Changes in the inflammatory and oxidative stress markers during a single hemodialysis session in patients with chronic kidney disease

BACKGROUND

Cardiovascular disease (CVD) is a common cause of morbidity and mortality in end-stage renal disease (ESRD) patients on hemodialysis (HD) among whom it is 5-20 times higher than in the general population. Some of the nontraditional risk factors such as oxidative stress and inflammation are related to the progress of CVD in HD patients. Several, but not all studies, reported that inflammatory and oxidative stress markers are increased during a single session of HD, mimicking changes that occur during acute immune activation. This study was taken up to evaluate the changes in the inflammatory and oxidative stress markers during a single HD session in patients with chronic kidney disease.

METHODS

Twenty-five ESRD patients on maintenance HD and 25 controls were included in the study. Blood samples were obtained from the patients before starting of hemodialysis (pre-HD) and after completion of hemodialysis (post-HD). The changes in serum Pentraxin-3, hs-CRP, malondialdehyde (MDA) and ferric reducing ability of plasma (FRAP) levels were measured in pre- and post-HD ESRD patients and compared with healthy control group.

RESULTS

This study found increased levels of Pentraxin-3, hs-CRP, MDA, and decreased level of FRAP in HD patients compared to controls.

CONCLUSIONS

Hemodialysis procedure contributes to inflammation and oxidative stress.

Dialyzer Reuse and Outcomes of High Flux Dialysis

Background

The bulk of randomized trial evidence for the expanding use of High Flux (HF) hemodialysis worldwide comes from two randomized controlled trials, one of which (HEMODIALYSIS, HEMO) allowed, while the other (Membrane Outcomes Permeability, MPO) excluded, the reuse of membranes. It is not known whether dialyzer reuse has a differential impact on outcomes with HF vs low flyx (LF) dialyzers.

Methods

Proportional Hazards Models and Joint Models for longitudinal measures and survival outcomes were used in HEMO to analyze the relationship between β2-microglobulin (β2M) concentration, flux, and reuse. Meta-analysis and regression techniques were used to synthesize the evidence for HF dialysis from HEMO and MPO.

Findings

In HEMO, minimally reused (< 6 times) HF dialyzers were associated with a hazard ratio (HR) of 0.67 (95% confidence interval, 95%CI: 0.48–0.92, p = 0.015), 0.64 (95%CI: 0.44 – 0.95, p = 0.03), 0.61 (95%CI: 0.41 – 0.90, p = 0.012), 0.53 (95%CI: 0.28 – 1.02, p = 0.057) relative to minimally reused LF ones for all cause, cardiovascular, cardiac and infectious mortality respectively. These relationships reversed for extensively reused membranes (p for interaction between reuse and flux < 0.001, p = 0.005) for death from all cause and cardiovascular causes, while similar trends were noted for cardiac and infectious mortality (p of interaction between reuse and flux of 0.10 and 0.08 respectively). Reduction of β2M explained only 1/3 of the effect of minimally reused HF dialyzers on all cause mortality, while non-β2M related factors explained the apparent attenuation of the benefit with more extensively reused dialyzers. Meta-regression of HEMO and MPO estimated an adjusted HR of 0.63 (95% CI: 0.51–0.78) for non-reused HF dialyzers compared with non-reused LF membranes.

Conclusions

This secondary analysis and synthesis of two large hemodialysis trials supports the widespread use of HF dialyzers in clinical hemodialysis over the last decade. A mechanistic understanding of the effects of HF dialysis and the reuse process on dialyzers may suggest novel biomarkers for uremic toxicity and may accelerate membrane technology innovations that will improve patient outcomes.

Effect of acute intradialytic strength physical exercise on oxidative stress and inflammatory responses in hemodialysis patients

Background

Oxidative stress and inflammation are common findings in chronic kidney disease (CKD) patients, and they are directly related to the increased risk of developing cardiovascular disease, which is the major cause of death in these patients, particularly for those undergoing hemodialysis (HD). Strength physical exercise is a new therapeutic approach to reduce these complications in CKD patients. Following this, the purpose of this study was to assess the effect of acute intradialytic strength physical exercise on oxidative stress and inflammatory responses in HD patients.

Methods

Sixteen HD patients were studied (11 women; 44.4±14.6 years; body mass index 23.3±4.9 kg/m²; 61.6±43.1 months of dialysis) and served as their own controls. Acute (single session) intradialytic physical exercise were performed at 60% of the one-repetition maximum test for three sets of 10 repetitions for four exercise categories in both lower limbs during 30 minutes. Blood samples were collected on two different days at exactly the same time (30 minutes and 60 minutes after initiating the dialysis—with and without exercise). Antioxidant enzymes activity [superoxide dismutase (SOD), catalase, and glutathione peroxidase], lipid peroxidation marker levels (malondialdehyde), and inflammatory marker levels (high-sensitivity C-reactive protein) were determined.

Results

SOD plasma levels were significantly reduced after acute physical exercise from 244.8±40.7 U/mL to 222.4±28.9 U/mL (P=0.03) and, by contrast, increased on the day without exercise (218.2±26.5 U/mL to 239.4±38.6 U/mL, P=0.02). There was no alteration in plasma catalase, glutathione peroxidase, malondialdehyde, or high-sensitivity C-reactive protein levels in on either day (with or without exercise). Additionally, there was no association between these markers and clinical, anthropometric, or biochemical parameters.

Conclusion

These data suggest that acute intradialytic strength physical exercise was unable to reduce oxidative stress and inflammation, and in addition, it seems to reduce plasma SOD levels, which could exacerbate the oxidative stress in HD patients.