Hemodialysis International
Volume 12 Issue 2 Page 173-210, April 2008
History of hemodialyzers' designs
Zbylut J. TWARDOWSKI
Division of Nephrology, Department of Medicine, University of
Missouri, Columbia, Missouri, U.S.A.
Correspondence to: Z. J. Twardowski, MD, PhD, Professor Emeritus of
Medicine, MA 436 Health Sciences Center, University of Missouri,
Columbia, MO 65212, U.S.A.
E-mail: twardowskiz@[EMAIL PROTECTED]
of knowledge requisite for development of hemodialysis
started in antiquity and continued through Middle Ages until the 20th
century. Firstly, it was determined that the kidneys produce urine
containing toxic substances that ac***ulate in the body if the kidneys
fail to function properly; secondly, it was necessary to discover the
process of diffusion and dialysis; thirdly, it was necessary to
develop a safe method to prevent clotting in the extracor****eal
circulation; and fourthly, it was necessary to develop biocompatible
dialyzing membranes. Most of the essential knowledge was acquired by
the end of the 19th century. Hemodialysis as a practical means of
replacing kidney function started and developed in the 20th century.
The original hemodialyzers, using celloidin as a dialyzing membrane
and hirudin as an anticoagulant, were used in animal experiments at
the beginning of the 20th century, and then there were a few attempts
in humans in the 1920s. Rapid progress started with the application of
cellophane membranes and heparin as an anticoagulant in the late 1930s
and 1940s. The explosion of new dialyzer designs continued in the
1950s and 1960s and ended with the development of capillary dialyzers.
Cellophane was replaced by other dialyzing membranes in the 1960s,
1970s, and 1980s. Dialysis solution was originally prepared in the
tank from water, electrolytes, and glucose. This solution was
recirculated through the dialyzer and back to the tank. In the 1960s,
a method of single-pass dialysis solution preparation and delivery
system was designed. A large quantity of dialysis solution was used
for a single dialysis. Sorbent systems, using a small volume of
regenerated dialysis solution, were developed in the mid 1960s, and
continue to be used for home hemodialysis and acute renal failure. At
the end of the 20th century, a new closed system, which prepared and
delivered ultrapure dialysis solution preparation, was developed. This
system also had automatic reuse of lines and dialyzers and prepared
the machine for the next dialysis. This was specifically designed for
quotidian home hemodialysis. Another system for frequent home
hemodialysis or acute renal failure was developed at the turn of the
21st century. This system used premanufactured dialysis solution,
delivered to the home or dialysis unit, as is done for peritoneal
dialysis.
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Wearable
Dictionaries define wearable as "suitable for easy wear, capable of
being worn." Hence, it has to be smaller than a ****table device. As
mentioned above, the first hint of the possibility of a wearable
artificial kidney was provided during the Meeting of the American
Society for Artificial Internal Organs in 1966.164 The idea was
adopted by Willem Johan Kolff and his collaborators from the Division
of Artificial Organs, College of Medicine, University of Utah, Salt
Lake City, UT, U.S.A. His collaborators included Stephen Jacobsen,
Robert L. Stephen, David Rose, Elisabet Atkin-Thor, and Edwin C.
Bulloch, who started to work on the wearable artificial kidney in the
early 1970s. They presented their device at the Twelfth Congress of
the European Dialysis and Transplant Association held in Copenhagen,
Denmark, in 1975,193 and at the Conference on Sorbents in Uremia and
Hepatic Failure in Brooklyn, NY, in November 1975.194 The system was
based on dialysate regeneration with activated charcoal, but because
of problems with urea adsorption, a detachable 20 L dialysate tank was
utilized. This tank also served as a carrying case. The authors
realized that the system was not yet wearable. They stated, "The word
"toward" in the title of this paper indicates that we know what our
goals are, but we have not the reached them yet."194 The same group
re****ted on an improved design in the early 1980s.195 The word
"wearable" in the title was replaced by the word "****table."
The work on wearable artificial kidneys continues, as the systems
developed so far have not been suitable for routine use. The most
recent re****t comes as a result of international cooperation of Andrew
Daven****t (Royal Free and University College Hospital Medical School,
London, UK), Victor Gura (Cedars-Sinai Medical Center, UCLA, David
Geffen School of Medicine, Los Angeles, CA, U.S.A.), Claudio Ronco
(Ospedale San Bortolo, Vicenza, Italy), Masoud Beizai and Carlos Ezon
(Xcor****eal Inc., Los Angeles, CA, U.S.A.), and Edmond Rambod
(BioQuantetics Inc., Los Angeles, CA, U.S.A.)196 The device weighs 5
kg and contains a high-flux dialyzer, a pulsatile pump for blood and
dialysate, a dialysate regeneration system, and monitors to secure
safe operation. The dialysate regeneration system contains a series of
sorbent canisters including urease, activated charcoal, hydroxyl
zirconium oxide, and zirconium phosphate, i.e., the same as in the
REDY system, but more compact and indeed wearable. The system was
evaluated in 8 patients during 4-hr to 8-hr sessions. The patients
were given unfractionated heparin for anticoagulation. The average
hourly Kt/Vurea was 0.035 in these 8 patients. Clotting occurred in 2
patients, and the fistula needle became dislodged in 1 patient. On the
basis of these preliminary results, the authors predict that "the
wearable hemodialysis device needs to be worn continuously, or for
extended periods every day to increase flows and therefore clearance
rates." Problems with clotting and blood access may be expected,
especially if the device needs to be used continuously.
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