High Efficacy Hemodiafiltration: Tomorrow's Extracorporeal Blood Purification Technology

Main Category: Urology / Nephrology
Also Included In: Medical Devices / Diagnostics
Article Date: 29 Nov 2008 - 1:00 PDT

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Suffering from end-stage renal disease (ESRD), a growing number of patients at the Centre hospitalier de l'Université de Montréal (CHUM), have become the beneficiaries of a North American breakthrough: high efficacy hemodiafiltration (HDF).

An extracorporeal blood purification technique, HDF is indicated for ESRD patients. Since the HDF unit was introduced in CHUM's Nephrology section, preliminary results show a clear advantage of high efficacy HDF over conventional hemodialysis in several areas, including the following:

• Improved removal of uremic toxins;
  
  
• Decreased number of hospitalization days;
  
  
• A better tolerance for patients;
  
  
• Minimizes the state of chronic inflammation that too often may lead to complications over a long course of dialysis;
  
  
• Diminished need for certain medications.
  
  
• Increased biocompatibility across the blood-dialysis system interface.

"Conventional hemodialysis continues to save lives, but we now have the technology to improve the lot of dialysis patients," says Dr. Rénee Lévesque, nephologist and lead physician in the HDF program at CHUM, and a professor with the medical faculty of the Université de Montréal. "At CHUM, we're proud to soon be accepting a cohort of forty patients undergoing HDF." Dr. Lévesque added that the CHUM Nephrology section is putting much efforts behind the new process, and hopes that one day soon all dialysis patients will be treated in this fashion.

Recent retrospective clinical data indicate 1, 2 that HDF reduces the mortality rates of dialysis patients and randomized studies are under way to provide clear proof of increased survival rates for patients. Among these, the CONTRAST3 study compares hemodialysis with online hemodiafiltration HDF in overall performance relative to cardiovascular morbidity and mortality. The study seeks to recruit seven hundred test subjects and follow them over a three-year period. CHUM is the only medical centre in North America to take part in this study, currently the largest in terms of the size of the randomized cohort.

Hemodiafiltration: the best of both worlds

HDF combines the elements of two processes, conventional hemodialysis (HD) and hemofiltration (HF). Renal replacement therapy for ESRD is based on two processes: diffusion and convection.

Conventional HD is diffusive; blood is circulated in an artificial kidney machine on one side of a semi-permeable membrane, while a special dialysis fluid is circulated on the other side. Small molecules of metabolic waste seep out into a dialysis solution flowing in the opposite direction on the other side of the membrane, mimicking the kidneys and washing wastes and toxins out of the bloodstream. One major toxin is urea. HD is the most widely used renal replacement function technology for ESRD.

Hemofiltration (HF) or ultrafiltration is exclusively convective, forcing blood through a filter under high pressure. The principle consists of applying a hydrostatic pressure gradient (high pressure on one side, low pressure on the other) across the membrane or filter. This results in an ultrafiltrate (water and electrolytes) on the other side. The quantity of ultrafiltrate lost in this process must be compensated by a matching infusion of replacement fluid. HF is used primarily in continuous mode and in acute care or intensive care.

In HDF, the diffusive component of HD is combined with the convective component of HF. As is the case in HF, the excessive loss of liquid must be compensated by the reinfusion of a sterile and apyrogenic (not producing fever) fluid. Recent developments have led to the "on-line" production of large volumes of ultrapure liquid of high quality. This has led to higher quality physicochemical and microbiological properties in these solutions, in comparison with HD.

Some statistics on the treatment of end-stage renal disease:

• At the end of 2003, there were 29,551 Canadians undergoing renal substitution treatment and that number is expected to double over the next ten years;
  
  
• Among that number, 61 % were in dialysis. Of these patients, 81 % were in hemodialysis and 19 % followed a regiment of peritoneal dialysis, e.g. from the abdomen.

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About CHUM

The Centre hospitalier de l'Université de Montréal (CHUM) provides specialized and ultra-specialized services to a regional and supra-regional clientele. Within its more immediate coverage area, the CHUM also provides general and specialized hospital care and services. The CHUM uses an integrated network model to carry out its five-part mandate of care, teaching, research, the assessment of technologies and health care methodologies, and the promotion of health care. Through its determined efforts to continuously improve quality of care and patient safety, the CHUM has again received accreditation from the Canadian Council on Health Services Accreditation, for the 2007-2010 period. Hôtel-Dieu, Hôpital Notre-Dame, and Hôpital Saint-Luc make up the CHUM, with approximately 10,000 employees, 880 physicians, 270 researchers, 5,000 students and trainees and 700 volunteers providing services to over a million patients each year. http://www.chumontreal.qc.ca (in French).

Source:

Renée Lévesque, M.D., FCRP
Centre hospitalier de l'Université de Montréal

Communications Department
Centre hospitalier de l'Université de Montréal (CHUM)

Information:

Nathalie Forgue, M.A., Communications Advisor
Centre hospitalier de l'Université de Montréal (CHUM)

1. Magnitude and impact of abnormal mineral metabolism in hemodialysis patients in the Dialysis Outcomes and Practice Patterns Study.
   
   
2. European Clinical Dialysis Database (EuCliD).
   
   
3. Effect of increased convective clearance by on-line hemodiafiltration on all causes and cardiovascular mortality in chronic hemodialysis patients - the Dutch CONvective TRAnsport STudy (CONTRAST).
   
   
4. 4 Source : The Canadian Kidney Foundation

Source: Nathalie Forgue
Université de Montréal Hospital Centre

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