ANAESTHESIA, SPINAL
A
anaesthesia, spinal
See
spinal anaesthesia.
anaesthetics
A term for the group of drugs that pro-
duce
anaesthesia
and for the medical
discipline that is concerned with their
administration.
An anaesthetist is a specialist who
administers anaesthetics. Before a patient
goes to the operating theatre, the anaes-
thetist assesses the condition of the
patient’s heart, lungs, and circulation.
He or she decides the type and amount
of drugs needed to induce and maintain
anaesthesia,
determines
the
patient’s
position on the operating table, watches
for problems, and decides on the action
to be taken if an emergency develops.
The anaesthetist is also responsible for
monitoring the progress of the waking
patient, and watching for and treating
any post-anaesthetic complications.
anal dilatation
A procedure in which the anus is
stretched. Anal dilatation is used to
treat conditions in which the anus be-
comes too tight, such as
anal stenosis
and
anal fissure.
It is also used to treat
haemorrhoids.
Anal dilatation is usually
performed
under
general
anaesthesia
(see
anaesthesia, general).
Reflex anal dilatation, in which the
anus dilates in response to local contact,
may occur in certain anal disorders or
after repeated anal penetration.
anal discharge
The loss of mucus, pus, or blood from
the
anus.
Haemorrhoids,
anal fissures
(tears), and
proctitis
(inflammation of
the rectum) can all cause anal discharge.
analeptic drugs
Drugs that stimulate breathing. Replaced
by
ventilation,
analeptic drugs are now
seldom used.
anal fissure
A common disorder of the anus that is
caused by an elongated ulcer or tear
that extends upwards into the anal canal
from the anal sphincter (the ring of
muscle that surrounds the anal orifice).
An anal fissure may be caused by the
passage of hard, dry faeces.
There is usually pain during defae-
cation, and the muscles of the anus may
go into spasm. There may also be a
small amount of bright red blood on
faeces or toilet paper.
The tear often heals naturally over a few
days, although spasm of the anal mus-
cles may delay healing. Treatment of
recurrent or persistent fissures is usually
by
anal dilatation
(a
procedure
to
enlarge the anus) and a high-fibre diet,
including whole-grain products, fruit
and vegetables, and plenty of fluids, to
help soften the faeces. Surgery to remove
the fissure is occasionally necessary.
anal fistula
An abnormal channel connecting the
inside of the anal canal with the skin
surrounding the anus.
An anal fistula may be an indication
of
Crohn’s disease, colitis,
or cancer of
the colon or rectum (see
colon, cancer of;
rectum, cancer of).
In most cases, it is the
result of an
abscess
that develops for
unknown reasons in the anal wall. The
abscess discharges pus into the anus and
out on to the surrounding skin.
An anal fistula is treated surgically
by opening the abnormal channel and
removing the lining. The operation is
performed under a general anaesthetic
(see
anaesthesia, general).
The wound is
then left to heal naturally.
analgesia
The loss of or reduction in pain sensa-
tion. Analgesia differs from
anaesthesia
(loss of all sensation) in that sensitivity
to touch is still preserved. Analgesia can
be induced by the use of
analgesic drugs.
analgesic drugs
COMMON DRUGS
o pio id s
•Co-codamol •Co-codaprin •Codeine
• Co-dydramol •Co-proxamol •Diamorphine
• Dipipanone •Fentanyl •Meptazinol
• Methadone •Morphine •Pentazocine
• Pethidine •Phenazocine •Tramadol
nsaids
•Aspirin •Celecoxib •Diclofenac
• Diflunisal •Etodolac •Fenbufen
• Fenoprofen •Flurbiprofen •Ibuprofen
• Indomethacin •Ketoprofen •Ketorolac
• Mefenamic acid •Naproxen •Piroxicam
• Rofecoxib
other nonopioids
•Nefopam •Paracetamol
Drugs used to relieve pain. The two
main types are nonopioid and
opioid
analgesics. Nonopioid analgesics are use-
ful for treating mild to moderate pain.
They include
paracetamol
for headache;
or
toothache
and nonsteroidal
anti-
inflammatory drugs (NSAIDs) such as
aspirin
and
ibuprofen,
which can help to
relieve
mild
pain
and
stiffness
in
arthritic conditions. Combinations of a
weak opioid (such as
codeine)
with a
nonopioid analgesic (such as aspirin)
relieve more severe pain. Potent opioids
such as
morphine
can produce
tolerance
and
drug dependence
and are used only
when other preparations are ineffective.
HOW THEY WORK
When body tissues are damaged, they
produce
prostaglandins
(chemicals that
trigger the transmission of pain signals
to the brain). Except for paracetamol,
nonopioid analgesics work by preven-
ting the production of prostaglandin;
paracetamol works
by
blocking
the
pain impulses within the brain itself,
preventing the perception of pain. Opi-
oid analgesics act in a similar way to
endorphins
(pain-relieving
substances
formed by the body) by blocking pain
impulses at specific sites in the brain
and spinal cord.
SIDE EFFECTS
Side effects are uncommon with para-
cetamol; aspirin and most NSAIDs may
irritate the stomach lining and cause
nausea, abdominal pain, and, rarely, a
peptic ulcer.
Nausea, drowsiness, consti-
pation, and breathing difficulties may
occur
with
opioid
analgesics.
The
euphoric effect produced by some opi-
oid analgesics have led to their abuse.
WARNING
Over-the-counter (nonopioid) analgesic
drugs should not be taken for longer
than 48 hours, after which time medi-
cal advice should be sought. If pain
persists, becomes more severe, recurs,
or differs from pain previously experi-
enced, a doctor should be consulted.
For precautions on specific drugs, see
the individual drug entries.
anal phase
A term used in
psychoanalytic theory
to
refer to a stage of a person’s psycho-
sexual
development. The anal phase
begins at around 18 months of age and
lasts for up to two years. (See also
geni-
tal phase; oral phase.)
anal stenosis
Tightness of the anus, sometimes known
as anal stricture. Anal stenosis prevents
normal passage of faeces, causing consti-
pation and pain during defaecation.
Anal stenosis may be present from
birth or may be caused by a number of
conditions in which scarring has occur-
red, such as
anal fissure, colitis,
or cancer
of the anus. The condition sometimes
occurs after surgery on the anus (for
example, to treat
haemorrhoids).
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