C H A P T E R 2 7
General and local anaesthetic agents
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be taken to prevent skin breakdown. Other problematic
effects are associated with the route of administration and
the amount of drug that is absorbed systemically. These
effects are related to the blockade of nerve depolarisation
throughout the system. Effects that may occur include
CNS effects such as headache (especially with epidural
and spinal anaesthesia), restlessness, anxiety, dizziness,
tremors, blurred vision and backache; GI effects such
as nausea and vomiting; cardiovascular effects such as
peripheral vasodilation, myocardial depression, arrhyth-
mias and blood pressure changes, all of which may lead
to fatal cardiac arrest; and respiratory arrest.
Clinically important drug–drug interactions
When local anaesthetics and succinylcholine are given
together, increased and prolonged neuromuscular
blockade occurs. There is also less risk of systemic
absorption and increased local effects if these drugs are
combined with adrenaline.
Prototype summary: Lignocaine
Indications:
Infiltration anaesthesia, peripheral and
sympathetic nerve blocks, central nerve blocks,
spinal and caudal anaesthesia, topical anaesthetic
for skin or mucous membrane disorders.
Actions:
Blocks the generation and conduction of
action potentials in sensory nerves by reducing
sodium permeability, reducing the height and
rate of rise of the action potential, increasing the
excitation threshold and slowing the conduction
velocity.
Pharmacokinetics:
Route Onset
Peak
Duration
IM 5–10 mins
5–15 mins 2 hours
Topical Not generally
absorbed
systemically
T
1/2
:
10 minutes, then 1.5 to 3 hours; metabolised in
the liver, excreted in the urine.
Adverse effects:
Headache, backache, hypotension,
urinary retention, urinary incontinence, pruritus,
seizures; when locally applied: burning, stinging,
swelling, tenderness.
Care considerations for
people receiving local anaesthetic agents
Assessment: History and examination
■
■
Assess for contraindications and cautions: any
known allergies to these drugs or to parabens
to
avoid hypersensitivity reactions
; impaired liver
function,
which could alter metabolism and
clearance of the drug
; low plasma esterases,
which
could lead to toxicity of esters
; heart block,
which
could be exacerbated by the drug effects
; shock
to
prevent altered local delivery and absorption
; and
current status of pregnancy or breastfeeding,
which
are cautions to the use of the drug.
■
■
Perform a physical assessment
to establish a
baseline status before beginning therapy and for
any potential adverse effects.
■
■
Inspect site for local anaesthetic application
to ensure integrity of the skin and to prevent
inadvertent systemic absorption of the drug.
■
■
Assess the person’s neurological status, including
level of orientation, reflexes, pupil size and
reaction, muscle tone and response and sensation,
to evaluate the effectiveness of the drug and
monitor for potential toxic neurological effects.
■
■
Monitor vital signs, including temperature, pulse
and blood pressure, and assess respiratory rate and
auscultate lungs
for adventitious sounds
to identify
changes and possible systemic absorption.
■
■
Monitor laboratory test results, such as liver
function tests and plasma esterases (if appropriate),
to determine possible need for dose adjustment.
■
■
Refer to the Critical thinking scenario for a full
discussion of care for a person who is receiving
local anaesthesia.
Implementation with rationale
■
■
Have emergency equipment readily available
to maintain airway and provide mechanical
ventilation if needed.
■
■
Ensure that drugs for managing hypotension,
cardiac arrest and CNS alterations are readily
available
in case of severe reaction and toxicity.
■
■
Ensure that the person receiving spinal anaesthesia
or epidural anaesthesia are well hydrated and
remain lying down for up to 12 hours after the
anaesthesia
to minimise headache.
■
■
Establish safety precautions
to prevent injury
during the time that the person has a loss of
sensation and/or mobility.
■
■
Provide meticulous skin care to the site of
administration
to reduce the risk of breakdown
.
■
■
Provide comfort measures
to help the person
tolerate drug effects.
Provide pain relief, as well as
skin care and turning
to prevent skin breakdown
,
and supportive care for hypotension
to prevent
shock or serious hypoxia.
■
■
Offer support and encouragement
to help the
person cope with the procedure and drugs being
used.
