Biomedical Engineering Reference
In-Depth Information
5.1
Chapter 5.1
Evolution of medical device
technology
Nandor Richter
The origins
illness be identified but also the ''quantity'' of the illness
be measured, could now be realized. Galileo stated
''measure the measurable and make measurable what was
not measurable till now.'' His words are equally impor-
tant and basic even today. One can apply this to all di-
agnostics and to most medical equipment.
In the early phase of civilization, instruments were used
in medical treatment. Healers used sharpened obsidian
stones for skull trepanation, and metal knives later
became common tools. Thousands of years ago doctors
sought to cast a glance into the human body. They tried to
observe the inner structure and the functioning of the
living organ through the mouth, the rectum, and the
vagina. Observation through these parts caused mini-
mum functional disorder, and minimal tools were
needed. Around 400 BC, Hippocrates was the first to
mention the endoscopy when he described a rectum
examination. At that time, a light source was not yet
available. Around AD 1000, the well-known Arab doctor
Abu al-Quasim used a glass mirror for vaginoscopy.
Because of inaccurate notions and the lack of measuring
instruments, observations could lead to only rough
conclusions.
The Enlightenment brought with it a significant im-
petus as the dogmatic, retarding forces of the Middle
Ages influenced scientific activities less and less. During
the seventeenth century, the exact sciences developed
vigorously. The curious human examined and understood
nature better and more objectively. Progress in healing
required the increasing application of tools and equip-
ment. For example, doctors realized rather early the
importance of body temperature and its fluctuation.
Again, it was Hippocrates who considered body tem-
perature as the most important sign in the case of acute
illnesses. However, it was not until around 1612 that the
Italian doctor Santorio made the first clinical thermom-
eter. He is also credited with the introduction of the
weight balance and hygrometer. With these devices, the
desire of Galen (
AD
131-201), that not only the type of
Temperature measurement
Thermometers have been enormously helpful to physi-
cians. Time series of temperatures were made possible,
providing information on the progress of an illness and
the trend of the patient's condition. One good indicator
of the importance of the thermometer is that over one
billion temperature measurements are carried out yearly
in the hospitals in the United States.
Physicians looked for symptoms that could increase
their knowledge about the condition of the patient, the
nature of illness, and its seriousness. Besides tempera-
ture, the color of the face, the color and odor of urine,
and the rhythm of the heart were all peculiar and per-
ceptible to the patient. It was desirable to measure these
parameters quantitatively and not simply to observe the
color of the patient's face. Quantifying color, heart
rhythm, and chemical composition of urine had to wait
for further developments in the chemical and technical
sciences.
Bioelectrical signals
The discovery of bioelectrical signals was of paramount
importance in that it led to diagnostic and therapeutic
applications. Today, we know that bioelectrical phe-
nomena are characteristic of all living organisms. Long
