Biomedical Engineering Reference
In-Depth Information
the membranous tubes, groves and ridges directed the flow of the dialyzer and
alternating layers of membranes material. Later, Skeggs adapted this technology
to autoanalyzers for assessing various components in the blood. In 1960, Norwe-
gian surgeon Fredrick Kiil developed an advanced form of parallel-plate dialyzers.
These Kiil dialysers were in clinical use until the late 1990s.
By the 1950s, Kolff's invention of the artificial kidney had solved the problem
of acute renal failure, but it was not seen as the solution for patients with chronic
renal disease. In the mid-twentieth century, American physicians believed it was
impossible for patients to have dialysis indefinitely for two reasons: they thought
no manmade device could replace the function of kidneys over the long term; and
a patient undergoing dialysis suffered from damaged veins and arteries, so that
after several treatments, it became difficult to find a vessel to access the patient's
blood. However, the scientific development of new materials started in 1900 with
the development of steel in 1900; vanadium alloy in 1912; stainless steel in 1926;
Bakelite and Pyrex in 1939; and nylon in 1940. New materials lead to new treat-
ment options. Physicians, engineers, and manufacturers joined in various modifica-
tions and innovations.
Belding Scribner, a professor of medicine at the University of Washington, came
up with the idea of connecting the patient to the dialyzer using plastic tubes, one
inserted into an artery and one into a vein [Figure 1.2(a)]. After treatment, the cir-
culatory access would be kept open by connecting the two tubes outside the body
using a small U-shaped device (popularly called a Scribner shunt), which would
shunt the blood from the tube in the artery back to the tube in the vein. The Scrib-
ner shunt was developed using Teflon material. With the shunt, it was no longer
necessary to make new incisions each time a patient underwent dialysis. In 1962,
Scribner started the world's first outpatient dialysis facility called the Seattle Artifi-
cial Kidney Center. Scribner faced an immediate ethical problem of who should be
given dialysis, since demand far exceeded the capacity of the six dialysis machines
at the center. Scribner decided that the choices should be made by an anonymous
admission committee composed of local residents from various walks of life in ad-
dition to two physicians who practiced outside of the field of nephrology. It was the
creation of the first bioethics committee (discussed in Chapter 11), which changed
the approach to accessibility of healthcare in the United States. In collaboration
with Albert Babb, a professor of nuclear engineering at the University of Washing-
ton, Scribner went on to develop a portable dialysis machine that could be oper-
ated by family members in their own homes. The portable unit also included many
safety features that would monitor if the system failed. The portable unit made it
easier for patients to maintain their daily routines and freed up machines in dialysis
centers. Hemodialysis established itself as the treatment of choice worldwide for
chronic and acute kidney failure after the early successes in Seattle. However, most
of these dialysers had very low efficiency, and the time of dialysis remained rela-
tively long, up to 8 hours. Such a schedule of 8 hours, three times weekly continued
to be practiced in some centers. Hence, there was a need for improving efficiency of
dialysis machines and industrial production in large numbers.
In 1964, American surgeon Richard D. Stewart built the hollow-fiber dialyz-
er containing nearly 1 m
2
of surface area of cellulosic material, large enough to
fulfill the one end of the dialyzer into thousands of tiny hollow fibers (~225-
μ
m
