Worlds of David Darling > Children's
Encyclopedia of Science > Health Revolution > 3. Lifesaving Machines
THE HEALTH REVOLUTION:
Surgery and Medicine in the Twenty-first Century
a book in the Beyond 2000 series by David Darling
3. Lifesaving Machines
Many people die needlessly each year simply because they don't receive medical
treatment early enough. Further developments in such scanning methods as
PET and MRI will mean that doctors will be able to detect the onset of life-threatening
diseases at an earlier stage. Even the smallest of tumors will be found
during routine scans and then, if necessary, will be treated by minimum-intervention
methods before the tumors have a chance to threaten a patient's life.
|A modern ambulance, equipped with advanced
lifesaving equipment, races to the scene of accident
More lives will also be saved in the future as a result of improvements
in the speed and effectiveness of treatment given to accident and emergency
victims. How soon a medical team can get to a critically ill patient and
what resources are immediately at hand can make the difference between life
and death for such patients.
No medical emergency is more urgent than a sudden heart attack, or cardiac
arrest. All at once and without warning, a person's heart stops beating
properly and the flow of blood to the brain is cut off.
|A heart attack victim being treated at home
by a rescuer using an automatic defibrillator
Even the short delay in getting a heart attack victim to a hospital may
be too long. For this reason, ambulance crews are trained in two basic methods
of revival. In the first, known as CPR (cardiopulmonary resuscitation),
a medical technician breathes into the patient's mouth and presses on the
chest repeatedly to keep the blood flowing and force oxygen as quickly as
possible to the brain, heart, and other vital systems.
The emergency crew may also use a DEFIBRILLATOR. This device consists of
two metal plates that can deliver a brief but powerful electric shock through
the patient's heart. The sudden shock interrupts the random twitching of
the heart muscles and stimulates the heart to resume its normal beating.
The difficulty is that too much time may pass before an expert is on hand
to work an ordinary defibrillator. However, newly developed automatic defibrillators
are helping to overcome this problem. The rescuer simply attaches sticky
electrodes to the victim's chest and the automatic defibrillator does the
rest. Programmed to measure the condition of the heart, it determines whether
to give a shock. If a shock is needed, it determines where this shock should
be directed and how strong it should be. A synthesized voice or visual display
guides the rescuer in setting up the device.
Another recent development is the surgically implanted defibrillator. This
is placed just under the skin of the patient's abdomen, where it continually
monitors the heart's beating with a microcomputer. If the beats become weak
and irregular, the device sends out a series of electrical pulses through
fine wires leading to the heart. The pulses continue for 15 to 20 seconds.
Since the pulse do not have to pass through the chest wall, they need only
about one-fifteenth as much energy to control heartbeat as a normal defibrillator
provides. The power source for the implant is a lithium battery that lasts
about three years and can be replaced at regular intervals during a minor
Monitors and Alarms
Doctors fighting to save the life of a critically ill or injured person
rely on an array of instruments to continuously monitor the patient's breathing
and heart condition. On of the most important tools at their disposal is
the electrocardiograph (EKG).
The electrocardiograph works by sensing the weak electrical currents produced
by muscles in the heart. These are transmitted to the machine through wires
from a number of electrodes, which are smeared with conducting paste and
fixed to the arms, legs, and chest. The EKG then amplifies the currents
about 3,000 times and traces the patterns of heart waves on a screen or
strip of paper.
A patient who is recovering from a heart attack or from cardiac surgery
is connected to an EKG in the recovery room. If the device senses that the
heart is behaving abnormally, it instantly sounds an alarm at the nearest
One of the latest monitoring devices is the niroscope. This can show within
two to three seconds whether the brain is receiving enough oxygen. Such
a warning may be crucial, for example, while the patient is under an anesthetic.
If deprived of oxygen for just three to four minutes, the brain would be
The niroscope works by shining infrared light of different frequencies through
the skull into the brain and measuring how much of that light is reflected
back out. The operation of the niroscope is based on the fact that brain
tissue absorbs different amounts of infrared light, depending on the amount
of oxygen available to the brain cells.
Another valuable new tool is the echocardiograph. This instrument records
the echoes of ultrasound waves from various parts of the heart. The instrument
can show blood clots, faulty valves, and other abnormalities of the heart
that might otherwise escape detection. One recent development of this technique
involves the use of tiny sound transmitters that provide an even clearer
image of the beating heart. The transmitters are located at the top if an
endoscope that is passed down the patient's throat. By altering the angle
and position of the tip of the endoscope, the doctor can accurately direct
ultrasound waves at a particular section of the heart and so obtain an image
of that section while the heart is beating.
|Machines That Changed Medicine
Stopping the heart long enough for surgery to be performed on it would
once have been unthinkable. But this procedure is now routinely carried
out, thanks to the development of the heart-lung machine. Blood from
the patient is pumped into the machine. There the blood is supplied
with oxygen – a task normally done by the lungs – and
then passed back into the patient.
|Surgeons perform surgery on a patient's
heart while another doctor watches the heart-lung machine used
to maintain the patient's circulation and vital functions during
Another great medical breakthrough has been the construction of a
machine to take over the role of the kidneys. These organs filter
blood to remove impurities that, if allowed to accumulate, can seriously
damage the body. Patients whose kidneys no longer work properly are
connected to a kidney dialysis machine several times a week. The machine
filters the blood artificially and returns the purified blood to the
body. At first, dialysis machines were large, expensive, and in short
supply, so difficult decisions had to be made concerning who would
receive treatment and who would not. But advances in the technology
of these devices have produced much smaller and less expensive machines
that can be installed at home, which makes more machines available
to more people.
In the battle against cancer, doctors now have a variety of different weapons
from which to choose. They can operate to cut away a tumor or burn it with
a high-energy laser, treat the patient with a combination of cancer-destroying
chemicals, or expose the diseased area to radiation.
|Proton accelerators show much promise in
treating cancer. Powerful magnets create a magnetic field that accelerates
protons to high speed. The protons can then be focused into a beam.
The patient is placed inside a vast rotating wheel. The focused beam
of protons breaks up the tumor, which is then excreted by the body.
Healthy tissue near the tumor is not damaged.
Bathing a tumor in radiation from a radioactive source, however, has the
side effect of damaging healthy tissue around the tumor. For this reason,
much interest is being shown in a new form of cancer treatment involving
Proton are positively-charged particles found inside the central part, or
nucleus, of atoms. Being electrically charged, protons can be accelerated
to high speed by a ring of powerful magnets inside a vast doughnut-shaped
proton accelerator. protons emerging from the accelerator can then be focused
into a tight beam and fired with great accuracy down a nozzle at the diseased
part of the patient's body.
The patient lies inside a giant rotating wheel that can direct the depth
of the proton beam coming from the accelerator to within an accuracy of
a few millimeters. Such fine targeting means that the maximum dose of radiation
can be delivered to the tumor. As a result, the tumor is broken up and is
then excreted by the body. Tissue lying in front of or behind the tumor,
however, is left undamaged since it is not subjected to such an intense
bombardment of protons.