Search

This article reviews the risks of transplanting hepatitis B core antibody (anti-HBc)-positive (+) kidneys and strategies to minimize the risks to the recipient. In the United States, there is a shortage of kidneys available for transplantation. Presently, 4% of kidneys transplanted are anti-HBc (+). In published retrospective studies, the serologic conversion rate for recipients of anti-HBc (+) kidneys varied between 0% and 27%; and the development of elevated hepatic transaminases varied between 0% and 26%. Only one published article had a trend toward increased risk of graft loss. Other published studies had no significant difference in graft or patient survival. Factors that influence the risk of transmission include hepatitis B viral load, vaccination, and antiviral therapy. If the donor is anti-HBc (+) and hepatitis B DNA negative, the risk of transmission is negligible; unfortunately, this information may not be available at the time of transplant. Vaccinated recipients with a protective hepatitis B surface antibody of at least 10 mIU/mL had a 4% conversion rate compared with 10% in recipients with antibody levels not exceeding 10 mIU/mL. Both hepatitis B immunoglobulin and lamivudine have been used in recipients of anti-HBc (+) kidneys to decrease seroconversion with success. The data do support the use of anti-HBc (+) kidneys if precautions are taken. The recipients should be informed of the risk, should be vaccinated with an adequate response, and should have surveillance serologies performed., (Copyright © 2010 Elsevier Inc. All rights reserved.)

Use of ultrapure dialysate (bacteria < 0.1 CFU/mL and endotoxin < 0.03 EU/mL) is associated with a reduction in inflammation and morbidity in patients treated with conventional thrice-weekly dialysis. The improved outcomes obtained with more frequent dialysis schedules have reawakened interest in home hemodialysis. More frequent dialysis also appears to reduce inflammation, and whether combining more frequent dialysis with use of ultrapure dialysate will have an additive effect on inflammation and its consequences remains unclear. Routinely producing ultrapure dialysate in a home environment with a conventional hemodialysis machine poses technical challenges related to the design of the equipment and the intermittent nature of hemodialysis. Solutions to these problems include use of a system in which the water-treatment equipment is fully integrated with the dialysis machine, use of dry-powder cartridges or sterile prepackaged liquids for bicarbonate concentrate, and use of a bacteria-retentive and endotoxin-retentive filter for final purification of the dialysate immediately before it enters the dialyzer. Alternatively, ultrapure dialysate may be achieved with newer machines designed specifically for home hemodialysis that use a new batch of dialysate for each treatment. The volume of dialysate available with these machines, however, currently limits their use to short-daily dialysis.

Dialyzer clearance depends on blood and dialysate flow rates and the product of the membrane surface area and mass transfer coefficient for the solute of interest, K(o)A. K(o)A is usually assumed to be constant for a given dialyzer and solute. Results of two recent studies challenge this assumption. Therefore, we examined the hypothesis that K(o)A depends on blood and dialysate flow rates during clinical dialysis. Urea clearances were measured for two different dialyzers at all four combinations of two blood flow rates (300 and 400 mL/min) and two dialysate flow rates (500 and 800 mL/min). Urea K(o)A was calculated by using standard equations for mass transfer in dialyzers operated with countercurrent flows. The impact of blood and dialysate flow rates on K(o)A was assessed by analysis of variance. Increasing dialysate flow rate from 500 to 800 mL/min significantly increased K(o)A (P = 0.018). Increasing blood flow rate from 300 to 400 mL/min did not significantly increase K(o)A (P = 0.083). Also, K(o)A decreased significantly with increasing hematocrit (P = 0.022). The results of this study extend previous in vitro findings by showing that increasing the dialysate flow rate increases urea K(o)A during clinical dialysis. However, the increase in K(o)A observed during clinical dialysis (5.7%) is less than that previously reported in vitro (14.7%), possibly because of the impact of blood cells and proteins on blood-side mass transfer resistance.

Anticoagulation with heparin is performed to prevent clotting during dialysis. However, heparin doses are usually determined empirically, and dialyzer clotting is a common reason for discarding reused dialyzers. We hypothesized that using a population pharmacodynamic model to determine individual heparin doses would improve dialyzer reuse rates. A previously published model was used to determine the loading dose and infusion rate of heparin needed to increase the intradialytic whole-blood clotting time to 150% of the predialysis value. The effectiveness of the model was assessed by comparing dialyzer reuse rates and delivered Kt/V(urea) before and after implementation of the model in 22 chronic hemodialysis patients. As an additional control, a similar group of 22 patients were followed up during the same period without adjustment of their heparin doses. Implementation of the model resulted in no change in the average loading dose (2,382 +/- 628 versus 2,425 +/- 908 IU; P = not significant) or average infusion rate (1,398 +/- 367 versus 1,393 +/- 532 IU/h; P = not significant) of heparin. However, individual patients required changes in loading dose or infusion rate. Dialyzer reuse rates increased significantly over time in the treatment group but remained unchanged in the control group (P < 0.003). Kt/V(urea) remained unchanged throughout the study period in both patient groups. From these data, we conclude that the use of a heparin model can improve dialyzer reuse rates without compromising the delivered dose of dialysis.

Orthotopic heart transplantation (OHT) is an accepted treatment for heart failure refractory to medical management. International registry data reported a 1-year survival after OHT of 79%. The risk factors associated with requiring continuous venovenous hemofiltration or hemodialysis and mortality in patients requiring continuous venovenous hemofiltration (CVVH)/hemodialysis (HD) have not been studied, since improvements have been made in OHT. We tested the hypothesis that requiring CVVH/HD in the immediate posttransplantation period increases mortality after OHT. We studied pretransplantation factors to predict those patients who would need CVVH/HD. Patients undergoing OHT from 1995 to 1996 were studied. Fifty-two patients underwent OHT. Eight patients (15%) needed CVVH/HD. Initial immunosuppression included cyclosporine, azathioprine, and solumedrol. Patients were changed to antilymphocyte therapy if they had oliguric acute renal failure, T or B cell incompatibility, or biopsy-proven rejection. Overall, survival at 1 year was 84.6%. Survival in patients not needing CVVH/HD was 91%, and survival in patients needing CVVH/HD was 36.5%. For each year of age over 55 years, patients had a relative risk of requiring CVVH/HD of 7.

A dialyzer is reused if its blood compartment volume is 80% of its initial value, a condition believed to ensure that the urea clearance remains at 90% of its initial value. This criterion was developed for dialyzers containing low permeability cellulose membranes reprocessed with formaldehyde. We tested the hypothesis that the criterion is also valid for more permeable membranes when dialyzers are reprocessed with peracetic acid/hydrogen peroxide. Kt/V for urea and reduction in beta2-microglobulin concentration were measured for up to 15 uses in dialyzers containing polysulfone or cellulose membranes. Kt/V for urea did not change for either dialyzer provided blood compartment volumes remained 80% of their initial value. The reduction in plasma beta2-microglobulin concentration from predialysis to postdialysis was 30% for the first use of the dialyzer containing polysulfone membranes, but decreased significantly (P = 0.042) following reuse to 12% for the tenth use. For the dialyzers containing cellulose membranes, the reduction in plasma beta2-microglobulin concentration was 18% for the first use and decreased to 12% by the twelfth use; however, this change was not significant. We conclude that removal of urea is maintained during reuse with peracetic acid/hydrogen peroxide provided the blood compartment volume remains 80% of its initial value. However, removal of beta2-microglobulin may not be maintained, even though blood compartment volumes remain at 80% of their initial value.