Artificial Support and Replacement of Human Organs - Biomimetics: Biologically Inspired Technologies - page 451

At the same time, Willem Kolff, who saw a young patient dying of kidney failure, reasoned that
if urea can be removed from the blood, then that can prevent patients from dying. Using a simple
sausage tubing made of cellophane he was able to remove urea from the blood; this lead to the
development of the artificial kidney or what we call today, the hemodialysis machine (Kolff, 2002).
A chance observation of blue blood turning red during the early experiments with rotating drum
kidney led to the development of disc oxygenators. This was later helpful in devising the oxygen-
ators in the heart-lung machine, and ultimately led to the development of modern artificial lung,
what is known as extracorporeal membrane oxygenation (ECMO) (Wolfson, 2003). Further
improvements in the artificial kidney led to the modern capillary membrane based hemodialysis
machines (Gottschalk and Fellner, 1997).
The work of Gott and Daggett was important in understanding the biocompatibility issues
in heart valve implants. They designed one of the first bileaflet heart valves, with a graphite-
benzalkonium-heparin coating, and later proved the extraordinarily low thrombogeneicity with
pyrolytic carbon (Gott et al., 2003). This has been the primary component of valve implants for the
last 35 years.
The story of development of artificial human organs is both fascinating and remarkable.
Fascinating because, it made possible things which could only be dreamed of before. And
remarkable in the unique collaboration that developed between doctors, engineers, scientists, and
physicists from diverse disciplines that led to the development of various organ support systems
and replacement options. From the highs of achievements in 1950s and 1960s to the recent ugly
lawsuits concerning patents for artificial support systems, artificial organ development has wit-
nessed both public curiosity and skepticism with equal measure.
We will be reviewing the relevant historical landmark later in this chapter when we look at the
individual organ replacement systems. I have tried to keep the language as simple as possible,
avoiding medical jargon to aid easier understanding by nonmedical readers. It is impossible to
cover all the technical and medical details of all the artificial organs and organ replacement systems,
but I have made every effort to provide a glimpse of this fascinating field. In a true sense of an
artificial organ, currently the heart is the only organ which can be replaced as an artificial implant in
the human body after removing the native heart, and as such I have focused on the current available
artificial heart and assist devices in more details. Other artificial medical implants have been
covered in corresponding chapters.

18.3 ARTIFICIAL KIDNEY

We have come a long way from the simple construct of sausage skin, a type of cellophane tubing
to remove toxins and harmful waste products (Kolff, 2002). The earlier advances consisted of
an artificial kidney made at Johns Hopkins by Abel and colleagues in 1913 using colloidon and
hirudin anticoagulant. It took another 15 years before the modification of the Hopkins kidney
was used by Hass in Germany to perform first clinical hemodialysis (Vienken et al., 1999). With
the use of a rotating drum kidney, developed by Willem Kolff in 1943, the modern era of
hemodialysis truly began (Gottschalk and Fellner, 1997). The advances in artificial kidney devel-
opment were halted due to the Second World War. Soon after the end of Second World War,
unprecedented technological developments made what was essentially an experimental therapy
into a routine clinical tool in treating kidney failure (Gottschalk and Fellner, 1997; Vienken
et al., 1999).
The modern dialyzers consist of semipermeable membranes which are configured into a hollow
fiber design. These membranes are essentially cellulose derived or noncellulose synthetic polymers.
High flux membranes have a higher ultra filtration coefficient which facilitates higher clearance of
the solutes during fluid removal. The technical and clinical aspects of the myriad of these devices
available are beyond the scope of this chapter.