Protein-bound solute removal during extended multipass versus standard hemodialysis.

BACKGROUND: Multipass hemodialysis (MPHD) is a recently described dialysis modality, involving the use of small volumes of dialysate which are repetitively recycled. Dialysis regimes of 8 hours for six days a week using this device result in an increased removal of small water soluble solutes and middle molecules compared to standard hemodialysis (SHD). Since protein-bound solutes (PBS) exert important pathophysiological effects, we investigated whether MPHD results in improved removal of PBS as well. METHODS: A cross-over study (Clinical Trial NCT01267760) was performed in nine stable HD patients. At midweek a single dialysis session was performed with either 4 hours SHD using a dialysate flow of 500 mL/min or 8 hours MPHD with a dialysate volume of 50% of estimated body water volume. Blood and dialysate samples were taken every hour to determine concentrations of p-cresylglucuronide (PCG), hippuric acid (HA), indole acetic acid (IAA), indoxyl sulfate (IS), and p-cresylsulfate (PCS). Dialyser extraction ratio, reduction ratio, and solute removal were calculated for these solutes. RESULTS: Already at 60 min after dialysis start, the extraction ratio in the hemodialyser was a factor 1.4-4 lower with MPHD versus SHD, resulting in significantly smaller reduction ratios and lower solute removal within a single session. Even when extrapolating our findings to 3 times 4 h SHD and 6 times 8 h MPHD per week, the latter modality was at best similar in terms of total solute removal for most protein-bound solutes, and worse for the highly protein-bound solutes IS and PCS. When efficiency was calculated as solute removal/litre of dialysate used, MPHD was found superior to SHD. CONCLUSION: When high water consumption is a concern, a treatment regimen of 6 times/week 8 h MPHD might be an alternative for 3 times/week 4 h SHD, but at the expense of a lower total solute removal of highly protein-bound solutes.

Multipass haemodialysis: a novel dialysis modality.

INTRODUCTION: Most home haemodialysis (HD) modalities are limited to home use since they are based on a single-pass (SP) technique, which requires preparation of large amounts of dialysate. We present a new dialysis method, which requires minimal dialysate volumes, continuously recycled during treatment [multipass HD (MPHD)]. Theoretical calculations suggest that MPHD performed six times weekly for 8 h/night, using a dialysate bath containing 50% of the calculated body water, will achieve urea clearances equivalent to conventional HD 4 h thrice weekly, and a substantial clearance of higher middle molecules. METHODS: Ten stable HD patients were dialyzed for 4 h using standard SPHD (dialysate flow 500 mL/min). Used dialysate was collected. One week later, an 8-h MPHD was performed. The dialysate volume was 50% of the calculated water volume, the dialysate inflow 500 mL/min-0.5 × ultrafiltration/min and the outflow 500 mL/min + 0.5 × ultrafiltration/min. Elimination rates of urea, creatinine, uric acid, phosphate and ß2-microglobulin (B2M) and dialysate saturation were determined hourly. RESULTS: Three hours of MPHD removed 49, 54, 50, 51 and 57%, respectively, of the amounts of urea, creatinine, uric acid, phosphate and B2M that were removed by 4 h conventional HD. The corresponding figures after 8 h MPHD were 63, 78, 74, 78 and 111%. CONCLUSIONS: Clearance of small molecules using MPHD 6 × 8 h/week will exceed traditional HD 3 × 4 h/week. Similarly, clearance of large molecules will significantly exceed traditional HD and HD 5 × 2.5 h/week. This modality will increase patients' freedom of movement compared with traditional home HD. The new method can also be used in the intensive care unit and for automated peritoneal dialysis.

Intraperitoneal heparin ameliorates the systemic inflammatory response in PD patients.

BACKGROUND: Patients with end-stage renal disease (ESRD) suffer from high mortality rates of cardiovascular diseases, conditions closely linked to the magnitude of their chronic low-grade inflammation. As heparins have been suggested to possess anti-inflammatory properties, we set out to investigate the impact of long-term treatment with intraperitoneal heparin on local and systemic inflammation in peritoneal dialysis (PD) patients. METHODS: In a double-blinded cross-over study, 21 PD patients with ESRD were randomised to inject either 4,500 anti-Xa IU tinzaparin or placebo (isotonic saline) into their morning dialysis bags every day for two periods of 3 months separated by a 1-month wash-out period. Blood and dialysate samples were analysed for inflammatory markers at the start and end of each treatment period. In dialysate, the appearance rates of the inflammatory markers were calculated to adjust for ultrafiltration variations. RESULTS: Eleven patients completed the trial. Treatment with intraperitoneal tinzaparin was accompanied with a median 25.8% reduction of the plasma C-reactive protein concentration (p = 0.032), a 7.3% reduction of the plasma fibrinogen concentration (p = 0.042) and a 54.5% reduction of the dialysate interleukin 6 appearance rate (p = 0.007) compared with placebo. CONCLUSION: Long-term treatment with intraperitoneal tinzaparin of ESRD patients on PD reduces local and systemic concentrations of inflammatory markers.