Oxidative stress in hemodialysis--postdialytic changes.

BACKGROUND: There is evidence for production of free oxygen radicals during hemodialysis. Hemodialysis is an intervention that is intermittent and is usually undertaken once in two or three days. It is known that the free oxygen radicals are short lived. Hence, it is necessary to know how long the effects of this oxidative stress are seen in the postdialytic period and whether they are carried over to the next dialysis. Review of the literature showed that there is no information in this area. Hence, this study was undertaken in order to learn whether oxidative stress due to a dialysis session is carried over to next dialysis session or not. METHODS: The effects were studied after four different types of membrane and dialysate--Polysulphone-Bicarbonate (PB), Polysulphone-Acetate (PA), Cuprophan-Acetate (CA) and Cuprophan-Bicarbonate (CB). Two consecutive dialysis sessions were studied to know the effect of re-use of the membrane. For each dialysis session, blood samples were collected at 0 (immediately prior to dialysis or preHD), 4 (immediate postdialysis), 6, 12, 24 and 48 hours (start of next session). Lipid peroxides, SOD and GP were determined in erythrocytes. Vitamins A and E and lipid peroxides were estimated in plasma. RESULTS: In the postdialytic phase there was an increase in plasma lipid peroxide levels. Plasma vitamin E levels increased significantly in all groups after first use dialysis, whereas the increase found after re-use dialysis was not statistically significant. Erythrocyte lipid peroxide levels showed a significant decrease. No significant changes were observed in the plasma vitamin A, erythrocyte SOD and GP levels. There was no significant change in any of the parameters between preHD and either 48-hour or 96-hour samples in all groups studied. CONCLUSIONS: Our results show that there is no carry-over of oxidative stress produced by dialysis to the next session regardless of the type of dialysis.

Oxidative stress in haemodialysis: immediate changes caused by passage of blood through the dialyser.

Oxygen free radicals have been implicated in the long-term complications of maintenance haemodialysis. Studies that have probed into the mechanisms of oxygen radical production have implicated the bio-incompatibility of dialysis membranes. Changes between the arterial (inlet) and venous (outlet) points of a dialyser may give a better picture of blood membrane interaction. There are very few studies on changes across the dialyser. Hence, it was planned to study the immediate changes that occur due to passage of blood through the dialyser. Changes between the arterial and venous ends of the dialyser after 1 h of dialysis were studied in four combinations of dialysate and membrane. There was a significant decrease in plasma vitamin E concentrations in all the groups during first-use dialysis. This was not observed with re-use dialysis. A decrease in plasma lipid peroxides was also observed in all the groups with both first and re-use dialysis. There was no significant difference in the parameters studied among the four types of dialysis. A less severe, reactive oxygen radical generation was observed with re-use of membranes.

Oxidative stress in haemodialysis--intradialytic changes.

Oxidative stress is likely to be involved in the development of complications due to haemodialysis. Though there is evidence for production of oxygen free radicals during haemodialysis, reports on net oxidative imbalance due to a single dialysis session are conflicting. Hence, a time-course analysis of changes in lipid peroxides (LPO) along with antioxidant enzymes and vitamins was carried out. Hourly changes in LPO and antioxidants were studied during a first-use cuprophan membrane and acetate dialysis in 20 patients on regular haemodialysis treatment. Data were corrected for haemoconcentration and standardised to measure the rate of change before statistical evaluation using analysis of variance for repeated measures. The results of the study showed a net oxidative stress due to a single dialysis session in the form of increased plasma and erythrocyte lipid peroxidation, decrease in plasma vitamin E, slight increase in plasma superoxide dismutase and erythrocyte glutathione peroxidase and no change in plasma glutathione peroxidase. erythrocyte superoxide dismutase and plasma vitamin A levels. The oxygen radical production was found to be maximum in the first hour of dialysis.

Thyroid hormone profile in peritransplant period in live donor kidney transplantation.

Chronic renal failure, characterised by two factors acting in opposite directions with respect to the serum thyroid homone levels was chosen for the study. Healthy controls, donors undergoing nephrectomy and renal transplant recipients were studied. In transplant recipients, presurgical levels of total thyroxine(TT4), free triiodothyronine(FT3) and free thyroxine(FT4) were lower than controls, and immediately after the release of arterial clamps, there was an upsurge of total triiodothyronine (TT3), TT4, FT3 and FT4 due to administered and/or endogeneously secreted catecholamines. The levels of the 7th day were comparable to the presurgical levels. The changes observed in donors and recipients were similar indicating that the hormonal changes observed are mostly due to surgical stress. Recovery in the hormonal status did not start in the first week of posttransplant period.