In Vivo Clearance and Elimination of Nine Marker Substances during Hemofiltration with Different Membranes

The handling of low, middle and high molecular weight markers was examined in seven stable dialysis patients during hemofiltration with different membranes. Four membranes were examined in a randomized, crossover order (polysulfone, polyamide, AN69 polyacrylonitrile, Asahi polyacrylonitrile) by measuring plasma and dialysate concentrations of phosphate, creatinine, vitamin B12, β2-microglobulin, furanic acid, hippuric acid, retinolbinding protein, alpha-1-antitrypsin, and albumin. Sieving coefficients and plasma clearances of β-microglobulin or retinol-binding protein were markedly or slightly lower during hemofiltration with the Asahi polyacrylonitrile membrane than with the other membranes (highest removal with polysulfone/AN69 polyacrylonitrile membranes). No differences of obvious clinical relevance could be seen between the four membranes. A high β2-microglobulin removal rate might be important to prevent dialysis-associated amyloidosis.

Influence of blood flow on adsorption of beta2-microglobulin onto AN69 dialyzer membrane

Adsorption onto the dialyzer membrane is a contributing factor to the elimination of beta2-microglobulin (beta2M) from the sera of uremic patients. The purpose of this prospective study was to ascertain the influence of the blood flow rate on adsorption of beta2M onto the polyacrylonitrile (AN69) hollow-fiber dialyzer membrane in 8 patients during regular hemodialysis (HD). Blood first passed through a low-flux polysulfone dialyzer and then through an AN69 dialyzer, which was not in contact with the dialysis fluid. During the investigation period (first hour of the HD session), the blood flow rate was 100 ml/ min (first part of the study), 200 ml/min (second part of the study), and 300 ml/min (third part of the study). Ultrafiltration was not performed during the investigation period. At the start of the HD sessions, the serum concentration of beta2M in the afferent blood line did not differ significantly among the 3 parts of the study. Serum beta2M was measured in samples taken from the afferent and efferent blood lines of the AN69 dialyzer at 5, 10, 15, 30, 45, and 60 min. The serum beta2M concentration decreased significantly in blood that had passed through the AN69 dialyzer. This decrease, indicating membrane adsorption, was maximal during the first part and minimal during the third part of study. The decrease in the contact time between the blood and the AN69 could be the underlying cause. The calculated quantities of beta2M adsorbed onto the AN69 membrane (44.2 +/- 10.2, 43.2 +/- 12.1, and 42.6 +/- 17.3 mg) did not differ significantly among the 3 parts of the study. These results suggest that an increase in blood flow rate from 100 to 300 ml/min did not significantly affect the quantity of beta2M adsorbed onto the AN69 membrane.

Removal of beta 2-microglobulin by hemodialysis and hemofiltration: a four year follow up

Efficient removal of total body burden beta 2-Microglobulin (beta 2-M) in uremia is a continuing challenge, as dialysis-related amyloidosis represents a major complication of chronic renal replacement therapy. To investigate long-term beta 2-M removal we studied 3 groups of stable end-staged renal failure patients over a period of 4 years; we compared low flux (cuprophane) hemodialysis (n = 12), high flux (polysulfone) hemodialysis (n = 12) and hemofiltration using high flux polysulfone (n = 8). In contrast to the cuprophane membrane, the polysulfone membrane eliminated considerable amounts of beta 2-M. This was associated with a sustained reduction of predialysis serum beta 2-M-levels (by 20%). Compared with high flux hemodialysis, hemofiltration provided a 50% higher elimination of beta 2-M. Thus, our long-term evaluation of beta 2-M removal suggests that hemofiltration rather than hemodialysis may be the treatment of choice for delaying the incidence of dialysis-related amyloidosis.

Angiotensin-converting-enzyme inhibitors and anaphylactoid reactions to high-flux membrane dialysis

In a retrospective study, 9 of 236 haemodialysis patients treated with high-flux polyacrylonitrile 'AN 69' membranes were found to have had anaphylactoid reactions. Treatment with angiotensin-converting-enzyme (ACE) inhibitors had been recently started in all 9 affected patients; only 5 of 227 unaffected patients had been treated with ACE inhibitors, and anaphylactoid reactions disappeared after discontinuation of ACE inhibitors.