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.