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P A R T 4
Drugs acting on the central and peripheral nervous systems
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Local anaesthetics block the depolarisation of nerve
membranes, preventing the transmission of pain
sensations and motor stimuli.
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Local anaesthetics are administered to deliver the
drug directly to the desired area and to prevent
systemic absorption, which could lead to serious
interruption of nerve impulses and response.
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Ester-type local anaesthetics are immediately
destroyed by plasma esterases. Amide local
anaesthetics are destroyed in the liver and have a
greater risk of accumulation and systemic toxicity.
KEY POINTS
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Provide thorough teaching, including anaesthetic
to be given, method for administration, activities
involved with administering and monitoring the
drug, and safety precautions.
Evaluation
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Monitor the person’s response to the drug (loss of
feeling in designated area).
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Monitor for adverse effects (respiratory depression,
blood pressure changes, arrhythmias, GI upset,
skin breakdown, injury, CNS alterations).
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Evaluate the effectiveness of the teaching plan (the
person can relate the anticipated effects of the drug
and the recovery process).
CRITICAL THINKING SCENARIO
Local anaesthesia
THE SITUATION
A.M., a 32-year-old male athlete with a history of asthma
(which could indicate pulmonary dysfunction), was
admitted to the hospital for an inguinal hernia repair.
At the person’s request, the surgeon elected to use a local
anaesthetic employing spinal anaesthesia. Because the
extent of the repair was unknown (A.M. had undergone
two previous repairs), bupivacaine, a long-acting
anaesthetic, was selected. He remained alert (blood
pressure 120/64 mmHg, pulse 62 beats/minute, respiration
rate 10/minute) and stable throughout the procedure. Two
hours after the conclusion of the procedure, A.M. appeared
agitated (blood pressure 154/68 mmHg, pulse 88 beats/
minute, respiration rate 12/minute). Although he did not
complain of discomfort, he did state that he still had no
feeling and had only limited movement of his legs.
CRITICAL THINKING
What safety precautions need to be taken?
What interventions should be done at this point?
How could the man be reassured?
Think about the anxiety
level of the man—an athlete who elected to have local
anaesthesia may have a problemwith control and feel
somewhat invincible. Consider the anxiety that loss of
mobility and sensation in the legs may cause in a person
who makes his living as an athlete.
In addition, consider the expected duration of action of
bupivacaine and the rate of return of function.
DISCUSSION
Bupivacaine is a long-acting anaesthetic with effects that
may persist for several hours. The timing of the drug’s
effects should be explained to A.M., and he should be
monitored for a period of time to determine whether his
agitated state and slightly elevated vital signs are a result of
anxiety or an unanticipated reaction to the surgery or the
drug. Life-support equipment should be on standby in case
his condition is a toxic drug reaction or some unanticipated
problem occurring after surgery.
The healthcare professional is in the best position to
perform the following interventions: explaining the effects
of the drug and the anticipated recovery schedule; keeping
the man as flat as possible to decrease the headache
usually associated with spinal anaesthesia; encouraging
the man to turn from side to side periodically to allow skin
care to be performed and to alleviate the risk of pressure
sore development; and staying with the man as much as
possible to reassure him, to answer his questions, and to
encourage him to talk about his feelings and reaction.
If the agitated state is caused by a stress reaction, the
man should return to normal; comfort measures, teaching
and reassurance should be provided. An elevated systolic
pressure with a normal diastolic pressure often is an
indication of a sympathetic stress response. An athlete is
more likely than most people to suffer great anxiety and
fear if his legs become numb and he is unable to move
them. Teaching and comfort measures may be all that is
needed to relieve the anxiety and ensure a good recovery.
CARE GUIDE FOR A.M.: LOCAL ANAESTHESIA
Assessment: History and examination
Assess for allergies to local anaesthetics or to parabens,
cardiac disorders, vascular problems, hepatic
dysfunction; also assess for concurrent use of
suxamethonium.
