CHLOASMA
CHOLANGIOGRAPHY
A second species of chlamydiae,
chlamy-
dia psittaci,
mainly affects birds but can
occasionally spread to people who have
contact with pigeons, parrots, parakeets,
or poultry, causing a type of pneumonia
called
psittacosis.
Treatment for chlamydial infections is
with
antibiotic drugs.
chloasma
A condition, also called melas-
ma, in which blotches of pale brown
pigmentation appear on the forehead,
cheeks, and nose. The pigmentation is
aggravated by sunlight. Chloasma some-
times develops during pregnancy. More
rarely, it is associated with the meno-
pause or use of
oral contraceptives.
The
condition usually fades but may recur.
chlorambucil
An
anticancer drug
used
to treat some types of cancer, for exam-
ple
Hodgkin's disease.
chloramphenicol
An
antibiotic
com-
monly used in the form of drops to treat
superficial eye infections. It is also used
to treat life-threatening infections when
the causative organism is unknown.
Rarely, tablets or injections are associ-
ated with aplastic
anaemia.
chlorate poisoning
The toxic effects
of chemicals present in some defoliant
weedkillers. Ingesting chlorates can cause
kidney and liver damage, corrosion of
the intestine, and methaemoglobinae-
mia (a chemical change in
haemoglobin
in the blood). Small doses of chlorates
can prove fatal. Symptoms of poisoning
include ulceration in the mouth, abdo-
minal pain, and diarrhoea.
chlordiazepoxide
A
benzodiazepine drug
mainly used to treat
anxiety
.
chlorhexidine
A type of disinfectant
mainly used to cleanse the skin before
surgery or before taking a blood sample.
chlorine
A poisonous, yellowish-green
gas with powerful bleaching and disin-
fecting properties. Inhaling even small
amounts is highly irritating to the
lungs; large amounts are rapidly fatal.
chloroform
A colourless liquid produc-
ing a vapour that was formerly used as a
general anaesthetic (see
anaesthesia,
general
). Chloroform is associated with
liver damage and heart problems, and
safer drugs are now used instead.
chloroquine
A drug used mainly in the
prevention and treatment of
malaria.
It is
also used as an
antirheumatic
to treat
rheumatoid arthritis
and
lupus erythema-
tosus
. Side effects are nausea, headache,
diarrhoea, rashes, and abdominal pain.
Long-term use may damage the retina.
chlorphenamine
An
antihistamine drug
used to treat allergies such as allergic
rhinitis
(hay fever), allergic
conjunctivitis
,
urticaria
, and
angioedem a
. It is also
found in some
cold rem edies
.
chlorpheniramine
An alternative name
for
chlorphenamine
.
chlorpromazine
A widely prescribed
antipsychotic
drug used to relieve symp-
toms of major psychotic illnesses such
as
schizophrenia
and
mania.
The drug
reduces delusional and hallucinatory
experiences and may have an effect on
irritability and overactivity. It is also
used as an antiemetic. Chlorpromazine
may cause photosensitivity of the skin
and, in some cases,
parkinsonism
, slow
reactions, and blurred vision.
chlorpropamide
A drug that is used to
treat
diabetes mellitus
(see
hypogly-
caemics,
ora/).
choanal atresia
A
congenital
defect of
the
nose
in which
1
or both of the nasal
cavities are not fully developed.
choking
Partial or complete inability to
breathe due to an obstruction of the
airways. Choking is often due to food or
drink entering the
trachea
and bronchi
instead of passing from the
pharynx
into
the
oesophagus
. Coughing normally dis-
lodges the food or drink. An obstruction
that partially blocks the airway and cannot
be dislodged by coughing is more seri-
ous. If the airway is completely blocked,
total suffocation will result if the block-
age is not removed. If an obstruction
cannot be cleared by first aid techniques,
such as the
Heimlich manoeuvre
or
removed manually, an emergency
tra-
cheostom y
may be performed to restore
the
airway
before
removal
of
the
obstruction with instruments.
cholangiocarcinoma
A
cancerous
growth in one of the
bile ducts
, which
causes jaundice and weight loss.
cholangiography
A procedure that uses
a
contrast medium
to make
bile ducts
visible on
X-rays.
Cholangiography is used
to look for biliary stones or to diagnose
narrowing or tumours of the bile ducts.
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