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P A R T 4
Drugs acting on the central and peripheral nervous systems
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Non-depolarising NMJ blockers prevent ACh from
exciting the muscle, and paralysis ensues because the
muscle cannot respond.
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Depolarising NMJ blockers cause muscle paralysis by
acting like ACh. They excite (depolarise) the muscle
and prevent repolarisation and further stimulation.
There is only one drug available in this class.
KEY POINTS
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Monitor for adverse effects (respiratory depression,
hypotension, bronchospasm, GI slowdown, skin
breakdown, fear related to helplessness and
inability to communicate).
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Evaluate effectiveness of the teaching plan (the
person can relate anticipated effects of the drug
and the recovery process).
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Monitor the effectiveness of comfort measures and
compliance with the regimen.
CRITICAL THINKING SCENARIO
Using suxamethonium in an elderly person
THE SITUATION
S.N., an 82-year-old Caucasian woman in very good health,
has been admitted to the hospital for an exploratory
laparotomy to evaluate a probable abdominal mass. On
admission, healthcare practitioners learned that she had
a history of mild hypertension that was well regulated
by diuretic therapy. She received a baseline physical
examination and preoperative instruction. On the morning
of the surgery, it was noted that the anaesthesiologist
planned to give her a general anaesthetic and
suxamethonium to ensure muscle paralysis.
CRITICAL THINKING
What areas must be considered for S.N.?
Consider the
woman’s age and associated chronic problems that often
occur with ageing. Also consider the support that she has
available and potential physical and emotional support that
she might need before and after this procedure. Use of a NMJ
blocker in the elderly presents some care challenges that
may not be seen with younger people.
What particular care activities should be considered
with S.N.?
Because S.N. has been maintained on long-
term diuretic therapy, she is at special risk for electrolyte
imbalance.
What, if any, complications could arise if S.N. has electrolyte
disturbances before surgery?
DISCUSSION
Before surgery, the preoperative teaching protocol should
be reviewed with the woman. S.N. should be advised that
she may experience back and neck pain secondary to the
muscle contractions caused by suxamethonium and throat
pain after the procedure. Reassure her that this is normal
and that medication will be made available to alleviate
the discomfort. Review deep breathing and coughing; she
may need encouragement to clear secretions from her
lungs and ensure full inflation. This is usually easier to do if
it is a familiar activity. S.N.’s serum electrolytes should be
evaluated before surgery because potassium imbalance can
cause unexpected effects with suxamethonium. Renal and
hepatic function tests also should be performed to ensure
that the dose of the NMJ blocker is not excessive.
During the procedure, S.N.’s cardiac and respiratory
status should be monitored carefully for any potential
problems; such effects are more common in people
with underlying physical problems. Because of S.N.’s age
and potential circulatory problems, she should receive
meticulous skin care and turning as soon as the procedure
allows this kind of movement. She should be turned
frequently during the recovery period, and her skin should
be checked for any breakdown. Clinical staff must remain
close by until she has regained muscle control and the
ability to communicate. She should be evaluated for the
need for pain medication and position adjustments.
S.N. will require additional teaching about her
diagnosis and potential treatment. This should wait until
she has regained her full ability to communicate and is able
to respond and participate in any discussion that may be
held. At that time, she may require emotional support and
encouragement. It may be necessary to contact available
family or social service agencies regarding her physical and
medical needs.
CARE GUIDE FOR S.N.: SUXAMETHONIUM
Assessment: History and examination
Assess allergies to the drug, and assess for history of
respiratory or cardiac disorders, myasthenia gravis,
hepatic or renal dysfunction, fractures, and glaucoma.
Concurrent use of aminoglycosides or calcium-channel
blockers.
Focus the physical examination on the following:
CV: Blood pressure, pulse rate, peripheral perfusion and ECG
CNS: orientation, affect, reflexes and vision
Skin: colour, lesions, texture and sweating
GU: urinary output and bladder tone
GI: abdominal examination
Respiratory: respirations and adventitious sounds
