EMG
E
part of the brain that controls vomiting
and/or by directly irritating the lining
of the stomach. The most widely used
emetic is
ipecacuanha
.
EMG
The abbreviation for electromyogram, a
recording of the electrical activity w ith-
in a
muscle
.
WHY IT IS DONE
An EMG can help to diagnose muscle
disorders, such as
muscular dystrophy
,
or
conditions in w hich the nerve supply to
the muscle is impaired, such as
neuropa-
thy
,
radiculopathy
,
or
motor neuron disease
.
In cases of nerve injury, the actual site of
the nerve damage can often be located.
HOW
IT
IS DONE
Electrical activity is measured during
muscle contraction and at rest. Small
disc electrodes are attached to the skin
over the muscle; alternatively, needle
electrodes are inserted into the muscle.
The
impulses
from
the
muscle
are
displayed on an
oscilloscope screen,
w hich shows muscle contraction and
relaxation in the form of a wave pattern
and reveals whether or not the muscle
activity is normal. A permanent record
can be made of the EMG. The procedure
has no side effects.
EMLA
An acronym for “ eutectic mixture of
local anaesthetics” . (The word “ eutec-
tic” means “ easily melted” .) EMLA is a
brand-named
cream
applied
to
the
skin to produce local anaesthesia (see
anaesthesia, local
) .
It is used to reduce
discomfort before intravenous injec-
tion and
venepuncture
,
particularly in
children, and before treating localized
skin conditions such as genital warts
(see
warts, genital
) .
emollient
A substance, such as lanolin or petrol-
eum
jelly,
that has a soothing
and
softening effect when applied to the
skin.
Emollients have a moisturizing
effect on the skin because they form
an
oily
film
on
its
surface,
w hich
prevents loss of water. Emollients are
used in creams, ointments, lotions, and
bath additives.
emotional deprivation
A lack of sufficient loving attention and
of warm, trusting relationships during
early childhood, causing normal emo-
tional
development
to
be
inhibited.
Emotional
deprivation
may
result
if
bonding
does not occur in the early
months of life or if a child is frequently
separated from his or her parents for
long periods during the first five years.
Emotionally deprived children may
be impulsive, unable to cope with frus-
tration, hungry for attention, and may
have impaired intellectual development.
emotional overlay
A
term
used
by
some
doctors
to
describe physical symptoms that they
feel have been worsened by emotional
difficulties. For example, it is common
for symptoms of a condition to worsen
when an individual is unhappy or w or-
ried. (See also
pain
. )
emotional problems
A common term for a range of psycho-
logical difficulties, often related to
anxiety
or
depression
.
Emotional problems may
have various causes.
empathy
The ability to understand and share the
thoughts and feelings of another per-
son.
In
psychoanalysis,
the
therapist
partly relies on empathy to establish a
relationship with a patient.
emphysema
A disease in w hich the walls of the
alveoli (see
alveolus, pulmonary
) are pro-
gressively destroyed, thereby reducing
the area of lung available for exchange
of gases. The alveoli, of w hich there are
many m illions in each lung, are groups
of air sacs at the end of bronchioles
(tiny air passages). Through their thin
walls, inhaled oxygen is passed into the
bloodstream
and
carbon
dioxide
is
removed from
the
capillaries to be
breathed out.
Emphysema usually develops along
with chronic
bronchitis
,
in a condition
known
as
chronic
obstructive
pul-
monary disease (see
pulmonary disease,
chronic obstructive
) .
CAUSES
In almost all cases, emphysema is a
direct result of smoking. In rare cases,
an inherited deficiency of a chemical
called alphaj-antitrypsin in the body
results in emphysema and, in a m inor-
ity of people, also affects the liver (see
alpha1-antitrypsin deficiency
) .
Tobacco smoke and other air pollu-
tants are believed to cause emphysema
by provoking the release of chemicals
within the alveoli that cause damage to
the alveolar walls. Alphaj-antitrypsin is
thought to protect against this chemical
damage; therefore, people with a defi-
ciency of this substance are particularly
badly affected by emphysema.
The damage is slight at first, but in
heavy smokers it becomes progressively
worse; the alveoli burst and merge to
form fewer, larger sacs with less surface
area, w hich consequently impairs oxy-
gen and carbon dioxide exchange. Over
the years the lungs become increasing-
ly less elastic, w hich further reduces
their efficiency.
SYMPTOMS AND
SIGNS
Initially, there are no symptoms, but as
the disease progresses and the lungs
suffer damage, there is an increasing
shortness of breath. In some people, the
chest becomes barrel-shaped as air is
trapped in the lungs. There may also be
a chronic cough (caused by the accom-
panying bronchitis) and a slight wheeze.
Eventually
(sometimes
after
many
years) the level of oxygen in the blood
starts to fall. In some cases,
pulmonary
hypertension
(raised blood pressure in
the pulmonary artery) develops, lead-
ing to
cor pulmonale
(enlargement and
strain on the right side of the heart).
Affected people start to turn blue due
to a lack of oxygen in the blood; their
legs subsequently swell as a result of
oedema
(accumulation of fluid in the
tissues).
Other sufferers are able
to
compensate for oxygen deficiency to
some extent by breathing faster, there-
by retaining their norm al colouring.
Many people show signs falling some-
where between these two extremes.
DIAGNOSIS
A diagnosis is made from the patient’s
symptoms
and signs,
from
a
chest
examination, and from various tests. A
blood sample from an artery may be
analysed to measure the concentration
of oxygen and carbon dioxide in the
blood; blood oxygen levels may alter-
natively be measured using an
oximeter
.
A blood test for alphaj-antitrypsin defi-
ciency may be performed if there is a
family history of the disorder. Chest
X-rays
are taken to exclude the possi-
bility of another lung disease being
responsible for the symptoms and to
determine how great an area of the
lungs has been affected.
Pulmonary func-
tion tests
are
carried
out
to
assess
breathing capacity and the efficiency of
the alveoli in exchanging gases.
TREATMENT AND
PREVENTION
Once the
damage to the lungs has
occurred, there is no treatment that can
264
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