title: Multipass haemodialysis: a novel dialysis modality.
abstract: BACKGROUND
  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 β2-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.
authors.affiliation: Department of Nephrology B, Herlev Hospital, University of Copenhagen, Copenhagen, Denmark. heaf@dadlnet.dk
authors.forename: James Goya
authors.initials: JG
authors.lastname: Heaf
authors.forename: Mette
authors.initials: M
authors.lastname: Axelsen
authors.forename: Robert Smith
authors.initials: RS
authors.lastname: Pedersen
mesh_terms: D000293:Adolescent; D000328:Adult; D015415:Biomarkers / Q000032:analysis*; D003404:Creatinine / Q000032:analysis; D015314:Dialysis Solutions; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007676:Kidney Failure, Chronic / Q000150:complications / Q000628:therapy*; D008297:Male; D008875:Middle Aged; D008962:Models, Theoretical; D010710:Phosphates / Q000032:analysis; D011379:Prognosis; D006435:Renal Dialysis; D014462:Ultrafiltration; D014508:Urea / Q000032:analysis; D014527:Uric Acid / Q000032:analysis; D055815:Young Adult
chemical_list: D015415:Biomarkers; D015314:Dialysis Solutions; D010710:Phosphates; D014527:Uric Acid; D014508:Urea; D003404:Creatinine
keywords: beta-2 microglobulin; dialysis adequacy; home haemodialysis