424
P A R T 4
Drugs acting on the central and peripheral nervous systems
■■
General anaesthetics must be administered by doctors
or anaesthetists trained in their administration and
prepared to provide constant monitoring and life
support measures to assist the person when the CNS
is depressed.
■■
General anaesthetics include barbiturates and
non-barbiturate drugs, which are administered
parenterally, and anaesthetic gases and volatile
liquids, which are administered through inhalation.
■■
People receiving general anaesthetics must be
constantly monitored because the CNS depression
can cause respiratory arrest, cardiovascular reactions
including hypotension and alterations in GI activity
that can lead to nausea and vomiting.
LOCAL ANAESTHESIA
Local anaesthesia
refers to a loss of sensation in limited
areas of the body. It can be achieved by several differ-
ent methods: topical administration, infiltration, field
block, nerve block and intravenous regional anaesthesia.
Topical administration
Topical local anaesthesia involves the application of a
cream, lotion, ointment or drop of a local anaesthetic
to traumatised skin to relieve pain. It can also involve
applying these forms to the mucous membranes in the
eye, nose, throat, mouth, urethra, anus or rectum to
relieve pain or to anaesthetise the area to facilitate a
medical procedure. Although systemic absorption is rare
with topical application, it can occur if there is damage
or breakdown of the tissues in the area.
Infiltration
Infiltration local anaesthesia involves injecting the anaes-
thetic directly into the tissues to be treated (e.g. sutured,
drilled, cut). This injection brings the anaesthetic into
contact with the nerve endings in the area and prevents
them from transmitting nerve impulses to the brain.
Field block
Field block local anaesthesia involves injecting the anaes-
thetic all around the area that will be affected by the
procedure or surgery. This is more intense than infiltra-
tion anaesthesia because the anaesthetic agent comes in
contact with all of the nerve endings surrounding the area.
This type of block is often used for tooth extractions.
Nerve block
Nerve block local anaesthesia involves injecting the
anaesthetic at some point along the nerve or nerves that
KEY POINTS
■
■
Monitor pulse, respiration, blood pressure,
ECG and cardiac output continually during
administration
to assess systemic response to CNS
depression and provide appropriate support as
needed.
■
■
Monitor temperature and reflexes
because dose
adjustment may be needed to alleviate potential
problems and to maximise overall benefit with the
least toxicity.
■
■
Institute safety precautions, such as side rails, and
monitor person until the recovery phase is complete
and the person is conscious and able to move and
communicate
to ensure safety.
■
■
Provide comfort measures
to help the person
tolerate drug effects.
Provide pain relief as
appropriate, along with reassurance and support
to deal with the effects of anaesthesia and loss
of control
, skin care and turning
to prevent skin
breakdown
and supportive care
for conditions
such as hypotension and bronchospasm.
■
■
Offer support and encouragement
to help the
person cope with the procedure and the drugs
being used.
■
■
Provide preoperative teaching,
realising that
most individuals who receive the drug will be
unconscious or will be receiving teaching about
a particular procedure:
–– Information about the anaesthetic (e.g. what to
expect, rate of onset, time to recovery)
–– Medications that may be used preoperatively
–– Effects of the medication on the person
preoperatively
–– Measures to maintain the person’s safety
preoperatively and during recovery
–– How the person will feel during the recovery
phase
–– Signs and symptoms to report during recovery
and afterward
Evaluation
■
■
Monitor response to the drug (analgesia, loss of
consciousness).
■
■
Monitor for adverse effects (respiratory depression,
hypotension, bronchospasm, slowed GI activity,
skin breakdown, malignant hyperthermia).
■
■
Evaluate the effectiveness of the teaching plan
(person can relate anticipated effects of the drug
and the recovery process).
■
■
Monitor the effectiveness of comfort and safety
measures.
