Dialyzers reuse

In a hollow fiber dialyzer the blood flows down the bore of the fiber, providing good fluid flow hydrodynamics. An advantage of the hollow fiber design is that only 60-100 mL of blood is required to fill the dialyzer. At the end of a dialysis procedure hollow fiber dialyzers can also be easily drained, flushed with sterilizing agent, and reused. Dialyzer reuse is widely practiced, in part for economic reasons, but also because the biocompatibility of the membrane appears to improve after exposure to blood. 

Z. Gunduz, R. Dusunsel R, K. Kose, C. Utas and P. Dogan, The Effects of Dialyzer Reuse on Plasma Antioxidative Mechanisms in Patients on Regular Hemodialysis Treatment. Free Radical Biology and Medicine 21(2) (1996) 225-231. 

Kaufman AM, Levin NW. Dialyzer reuse. In Daugirdas JT, Blake PG, Ing TS, eds. Handbook of Dialysis. Philadelphia, Lippincott Williams Wilkins, 2001 169-181. 

Dialyzer membrane bioincompatibility, hence complement activation, is maximal with the first use of cuprophane membranes, is considerably less with cellulose acetate, and is negligible or absent with polyacrylonitrile and polymethacrylate membranes. With dialyzer reuse, complement activation is greatly attenuated (C2). The effects of dialysate and dialyzer on the induction of hypoxemia are additive, so that hypoxemia is greatest during the first use of a cuprophane membrane and acetate bath, but is much improved by the substitution of a bicarbonate bath. The use of a polyacrylonitrile or polymethacrylate membrane with a bicarbonate bath will not cause hypoxemia (D3). 

Fresh high-flux dialysis membranes achieve approximately 23—37% reductions in plasma P2M levels [344]. However, dialyzer reuse significantly impairs the removal of P2M [345]. Indeed, it has been recognized that non-specific adsorption of middle molecules on the surface of these synthetic high-flux membranes, rather than difiusion through the membrane, can account for significant amounts of the device s clearance [346, 347]. With the surface area of membranes in the dialysis device amounting to less than 2 m, the adsorption capacity of the device is obviously too small. 

With the planned consolidation of the top four U.S. dialysis providers into two vertically integrated companies, the field of available dialyzers is likely to narrow. Meanwhile, the decrease in dialyzer reuse will continue to drive increased production. Given that the Center for Medicare and Medicaid Services (CMS), formerly known as the Healthcare Financing Administration (HCFA), will continue its downward pressure on costs, and possibly institute a capitated payment system (i.e., a fixed monthly payment to cover all patient costs including hospitalization), only incremental improvements in commercially available dialyzer membranes are expected in the next 5 years. 

The membrane separates the blood from a dialyzing solution, or dialysate, that is similar to blood plasma in its concentration of needed substances (e.g., electrolytes and amino acids) but contains none of the waste products. Because the concentrations of undesirable substances are thus higher in the blood than in the dialysate, they flow preferentially out of the blood and are washed away. The concentrations of needed substances are the same on both sides of the membrane, so these substances are maintained at the proper concentrations in the blood. The small pore size of the membrane prevents passage of blood cells. However, Na and Cl ions and some small molecules do pass through the membrane. A patient with total kidney failure may require up to four hemodialysis sessions per week, at 3 to 4 hours per session. To help hold down the cost of such treatment, the dialysate solution is later purified by a combination of filtration, distillation, and reverse osmosis and is then reused. 

The final component of the dialysis prescription that may affect drug clearance by dialysis is whether or not the patient has anthorized the unit to reuse his or her dialyzer. Currently, more than 75% of all dialysis units in the United States use this procedure to reduce the cost of chronic hemodialysis. The effect of dialysis filter reuse on the clearance of endogenous molecules such as urea, creatinine, and P2-microglobulin has been evaluated for many dialyzers. A decrease in urea and creatinine clearances and an increase in /S2-mictoglobulin clearance was observed with some, but not all, dialyzers. Only one center has evaluated the effect of reuse on drug clearance (cefazolin, ceftazidime, tobramycin, and vancomycin) following the first and tenth use of cellulose acetate, cellulose triacetate, and polysulfone... 

D-Tube dialyzer may be reused a few times after extensive washing with water and storage in water with 0.1% NaNj. The water must be removed completely before filling with the RM. 

The number of dialysis patients is estimated to grow by 10 to 20 percent per year. The demand for dialyzers also depends on how many times the patient must be treated each week, and whether the dialyzers are reused. Typically, patients require treatment three times per week, or an... 

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