Biomedical Engineering Reference
In-Depth Information
from the body, and filtering over 400 gallons of blood daily. When the kidneys are
not functioning correctly, pathological conditions are caused by the accumulation
of waste products. The body swells, and if there is no intervention, death results.
Acute and chronic kidney failure is an illness that is as old as humanity itself and
can lead to death if untreated for several days or weeks. In early Rome and later in
the Middle Ages, treatments for uremia (Greek for urine poisoning, or “urine in the
blood”) included the use of hot baths and sweating therapies. Since an individual
can only last a short time with total kidney failure, dialysis was developed as a
method of keeping a person alive until a suitable organ donor could be located.
Current procedures for the treatment of kidney failure include hemodialysis and
peritoneal dialysis, developed on the principles of osmosis, diffusion, and ultrafil-
tration (separation based on the size of the particles).
Hemodialysis
is a more frequently prescribed type than peritoneal dialysis.
The treatment involves circulating the patient's blood outside of the body
through a dialysis circuit [Figure 1.2(a)]. Two needles are inserted into the
patient's vein, or access site, and are attached to the dialysis circuit, which
consists of plastic blood tubing, a filter known as a dialyzer, and a dialysis
machine that monitors and maintains blood flow and administers dialysate.
Dialyzer
Roller Pump
Out
In
Patient's Arm
(a)
Dialysate in
Hollow fibers
Blood
out
Blood
in
Jacket
Dialysate out
(b)
Figure 1.2
Hemodialysis. (a) Flow loop of the hemodialysis. (b) Components in the hollow-fi ber
dialyzer.
