BAROTRAUMA
used to drain urine from the bladder
(see
catheterization, urinary).
Balloon cath-
eters are sometimes used to expand
narrowed arteries (see
angioplasty, bal-
loon).
They may also be used to control
bleeding from widened veins in the
lower part of the oesophagus (known as
oesophageal varices
) before surgery.
balm
A soothing or healing medicine applied
to the skin.
balsam
An aromatic oily liquid that is obtained
from various evergreen trees. Balsam is
an
antiseptic
substance and was once
also widely used in remedies for respir-
atory disorders.
bambuterol
A
bronchodilator drug
that is taken orally
for the relief of
asthma
.
bandage
A strip or tube of fabric used to keep
dressings
in position, to apply pressure,
to control bleeding, or to support a
sprain or strain. Roller and tubular ban-
dages are the type most widely used.
Tubular gauze bandages require a spe-
cial applicator and are used mainly for
areas that are awkward to bandage, such
as a finger. Triangular bandages are used
to make
slings.
(See also
wounds.)
banding
A procedure for treating
haemorrhoids
(piles) that are large or are causing
particular discomfort. Using a special
instrument, a doctor places a rubber
band around the base of the haemor-
rhoid, which causes it to shrink and,
eventually, to fall off. Banding is virtually
painless and the procedure can be per-
formed in a doctor’s surgery
barber’s itch
See
sycosis barbae.
barbiturate drugs
COMMON DRUGS
• Amobarbital •Butobarbital •Phenobarbital
• Secobarbital •Thiopental
A group of sedative drugs that work by
depressing activity within the brain.
Barbiturate drugs include thiopental,
which is very short-acting and is used
to induce anaesthesia (see
anaesthesia,
general
), and phenobarbital, which is
long-acting and is sometimes used as
an
anticonvulsant drug
in the treatment
of epilepsy In the past, barbiturates
were widely used as
antianxiety drugs
and
sleeping drugs,
but they have been
largely replaced by
benzodiazepine drugs
and other nonbarbiturates. Because bar-
biturates
are
habit-forming
and
are
widely abused for their sedative effect,
they are now classed as
controlled drugs.
HOW THEY WORK
The sedative action of barbiturate drugs
is produced by the drug molecules
blocking the conduction of stimulatory
chemical signals between the nerve cells
of the brain and reducing the ability of
the cells to respond. Barbiturates, espe-
cially phenobarbital, also reduce the
sensitivity of brain cells to abnormal
electrical activity.
POSSIBLE SIDE EFFECTS
The possible adverse effects of barbitu-
rate drugs include excessive drowsiness,
staggering gait, and, in some cases,
excitability. An overdose of barbiturates
can be fatal, particularly when taken in
combination with alcohol, which dan-
gerously increases their depressant effect
on the brain (including suppression of
the respiratory centre).
Barbiturates are likely to produce
drug
dependence
if used for longer than a few
weeks, and withdrawal effects, such as
sleeplessness and twitching, may then
occur when treatment is stopped.
Bardet-Biedl syndrome
A very rare
genetic disorder
characterized
by
learning difficulties, retinopathy
(an eye
defect),
obesity, polydactyly
(the presence
of extra fingers or toes) and
hypogonadism
(underactivity of the testes or ovaries).
barium sulphate
A salt that is used in solution as a
contrast medium
in X-ray examinations
of the intestinal tract (see
barium X-ray
examinations).
Barium is opaque to X-
rays and is used to view the outline of
hollow internal organs, which would
otherwise not be visible.
barium X-ray examinations
Procedures used to detect and follow
the progress of some disorders of the
gastrointestinal tract. Because barium (a
metallic element) is opaque to X-rays, it
is used to outline organs, such as the
stomach, which are not normally visi-
ble on an X-ray image. Barium sulphate
mixed with water is passed into the part
of the
tract
requiring
examination
before X-rays are taken. In some cases,
barium X-ray examinations can be used
as an alternative to
endoscopy
(internal
examination using a rigid or flexible
viewing tube), although endoscopy is
often the preferred form of investigation.
Barium X-rays may be single- or dou-
ble-contrast. Single-contrast X-rays use
barium sulphate alone. The barium fills
the section of the tract under examina-
tion and provides an outline image that
shows up any prominent abnormalities.
In double-contrast barium X-rays, the
barium forms a thin film over the inner
surface of the tract and the tract is sub-
sequently filled with air so that any
small surface abnormalities can be seen.
TYPES OF EXAMINATION
Various types of barium X-ray exam-
ination are used to investigate different
parts of the gastrointestinal tract. A
barium swallow involves drinking a sol-
ution of barium; this procedure is used
to investigate the swallowing mechan-
ism or the oesophagus. A barium meal
is carried out to look at the lower
oesophagus, stomach, and duodenum.
A barium follow-through examination
can be used to investigate disorders of
the small intestine; after barium has been
swallowed, a series of X-rays are taken
at intervals as the barium travels down
the oesophagus to the intestine. A barium
enema can be used to investigate disor-
ders of the large intestine and the rectum;
the barium is introduced into the body
through a tube inserted in the rectum.
Any barium that remains in the intes-
tine may be a cause of constipation. For
this reason, it is important to ensure
that a patient has a high-fibre diet and
drinks plenty of water following a bar-
ium examination, until all the barium
has passed through. (See also
Barium
X-ray procedures
box, overleaf.)
barotrauma
Damage or pain, mainly affecting the
middle
ear
and the facial
sinuses,
that is
caused by changes in surrounding air
pressure. Air travellers are at the greatest
risk of barotrauma, but scuba divers
face similar problems.
CAUSE
Aircraft cabin pressure decreases as the
plane ascends and increases as it des-
cends. As the aircraft ascends, the ears
may seem to “pop” as the air in the
middle ear expands and is expelled via
the eustachian tubes, which connect the
middle ear to the back of the throat. On
descent, the higher pressure may push
the eardrum inwards and cause pain.
B
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