as is knee-joint replacement. Replace-
ment of other joints, such as the finger
(see finger-joint replacement), shoulder,
and elbow, is also common.
arthroscopyInspection through an en-
doscope(viewing tube) of the interior of
a joint. Arthroscopy is most often used
to diagnose disorders of the knee joint
but can also be used in other joints
such as the shoulder, hip, or wrist. It
allows the surgeon to see the surface of
the bones, the ligaments, the cartilages,
and the synovial membrane. Specimens
can be taken for examination. Some
surgical procedures, such as removal of
damaged cartilage, repair of ligaments,
and shaving of the patella (kneecap),
are usually performed arthroscopically.
artificial inseminationA form of as-
sisted conception in which semen is
introduced artificially into the uterus,
instead of by sexual intercourse, with
the aim of inducing pregnancy.
There are 2 types of artificial insemi-
nation: AIH, artificial insemination with
the semen of the woman’s male partner;
and AID, insemination with a donor’s
sperm. AIH is usually used for couples
who are unable to have intercourse, or
if the man has a low sperm count or a
low volume of ejaculate. It is also used
when semen has been stored from a man
prior to treatment (such as chemother-
apy) that has made him sterile. AID is
available to couples if the man is infer-
tile or is a carrier of a genetic disease. It
may also be used by a woman who
wants children but has no male partner.
Insemination is timed to coincide with
natural ovulation or may be combined
with treatment to stimulate ovulation.
artificial kidneyThe common name
for the machine used in dialysis.
artificial respirationForced introduc-
tion of air into the lungs of someone
who has stopped breathing (see respir-
atory arrest) or whose breathing is
inadequate. As an emergency first-aid
measure, artificial respiration can be
given mouth-to-mouth or mouth-to-
nose, which can prevent brain damage
due to oxygen deprivation; a delay in
breathing for more than 6 minutes can
cause death. Cardiac compressions may
also be necessary if poor respirationhas led to cessation of the heartbeat
(see cardiopulmonary resuscitation). Arti-
ficial respiration can be continued by
use of a ventilator (see ventilation).
artificial rupture of membraneSee
amniotomy.
artificial sweetenersSynthetic substi-
tutes for sugar that are used by people
on slimming diets and by the food
industry. Saccharin and aspartame are
often recommended in calorie-controlled
diets but are of questionable value
because the appetite compensates for
the lack of calories from sugar, and
other foods are eaten to maintain the
calorie intake. Sorbitol is an artificial
sweetener that is useful for diabetics,
but it can cause diarrhoea and bloating
when consumed in large quantities.
arytenoidOne of 2 pyramid-shaped
cartilages that form part of the larynx.
asbestos-related diseasesA variety of
diseases caused by inhalation of asbes-
tos fibres. Asbestos is a fibrous mineral
formerly used as a heat- and fire-resis-
tant insulating material. There are 3
main types of asbestos fibre: white,
which is widely used; blue; and brown,
the most dangerous. The use of all
types is now carefully controlled.
In asbestosis, widespread fine scarring
occurs in the lungs. The disease causes
breathlessness and a dry cough, even-
tually leading to severe disability and
death. It develops mostly in industrial
workers who have been heavily exposed
to asbestos. The period from initial
exposure to development of the disease
is usually at least 20 years. Diagnosis is
by chest X-ray. Asbestosis increases the
risk of lung cancer.
Mesotheliomais a cancerous tumour
of the pleura(the membrane surround-
ing the lungs) or the peritoneum (the
membrane lining the abdominal cavity).
In the pleura, mesotheliomas cause pain
and breathlessness; in the peritoneum
they cause enlargement of the abdo-
men and intestinal obstruction. The
condition cannot be treated and usually
leads to death within 1 or 2 years. The
average interval between initial exposure
to asbestos and death is 20–30 years.
Mesothelioma affects people who have
worked with blue or brown asbestos.ARTHROSCOPY ASBESTOS-RELATED DISEASESA