A critical review of sodium profiling for hemodialysis.

In sodium profiling, the sodium concentration in the dialysis fluid, instead of being constant, follows a time-dependent profile over the course of a hemodialysis session. The main aim of this manipulation is to avoid osmotic disequilibrium by keeping plasma osmolality in the physiological range. Further advantages of sodium profiling are a reduction in the incidence of muscle cramps, improved sodium removal, and improved vascular stability. Many different profiles have been used by various investigators. However, if sodium profiling is not appropriately conducted, sodium accumulation with resulting augmented thirst, increase of interdialytic weight gain, and hypertension may result. Sodium accumulation may, in fact, explain the reduced intradialytic morbidity reported in some short-term sodium profiling studies. Randomized, double-blind studies meeting strict statistical criteria and providing a careful control to maintain equivalent sodium balances between the compared treatments are difficult to perform and have not yet been published. However, because sodium profiling has potential benefits, provided that sodium balance is carefully controlled, it should nevertheless be regarded as a tool that experienced nephrologists can use for the treatment of patients who experience intolerable side effects during standard dialysis.

No generation of bradykinin with a new polyacrylonitrile membrane (SPAN) in haemodialysis patients treated with ACE inhibitors.

BACKGROUND: Anaphylactoid reactions occurring in uraemic patients haemodialysed with polyacrylonitrile haemodialysis (HD) membranes and being treated with ACE inhibitors have been attributed to an excessive generation of bradykinin. METHODS: Here we tested in a prospective trial a new type of polyacrylonitrile membrane (SPAN) with respect to bradykinin generation in nine HD patients receiving either captopril or enalapril. Each patient had three consecutive HD sessions with each of the three tested membranes, high-flux SPAN, high-flux polysulphone (F60) and low-flux Hemophan (GFS Plus 16). RESULTS: No clinical signs of anaphylactoid reactions were observed in any of these patients but the number of patients was relatively small and the duration of exposure to different membranes relatively short. At 5 min after the start of HD session, plasma bradykinin levels were significantly higher in the venous than in the arterial line for all three HD membranes: SPAN, 18.5 +/- 11.9 versus 12.4 +/- 5.3 fmol/ml (P < 0.05); F60, 19.0 +/- 13.8 versus 11.5 +/- 6.5 fmol/ml (P < 0.01); and GFS Plus 16, 39.1 +/- 22.9 versus 15.8 +/- 12.4 fmol/ml (P < 0.005), mean +/- SD respectively. Higher venous line levels were still observed at the 15 and 60 min time points for F60 and GFS Plus 16, but not for SPAN. However, these levels were still insignificant compared to levels measured during episodes of anaphylactic shock from the literature. Plasma histamine and C5a anaphylatoxin levels did not show any increase during HD with SPAN. CONCLUSION: The SPAN membrane did not induce significant bradykinin release in dialysis patients on ACE-inhibitor therapy. It may therefore be used for high-flux dialysis in such patients.