C H A P T E R 3 1
Adrenergic blocking antagonists
473
■■
Adrenergic blocking agents block the effects of
the SNS.
■■
The non-selective adrenergic blocking agents
block all receptors, that is, both alpha- and
beta-receptors.
■■
Selective adrenergic blocking agents have specific
affinity for alpha- or beta-receptors or for specific
alpha
1
-, alpha
2
-, beta
1
- or beta
2
-receptor sites.
■■
Blocking all of the receptor sites within the SNS
results in a lowering of blood pressure.
KEY POINTS
Care considerations for people receiving
non-selective adrenergic blocking agents
Assessment: History and examination
■
■
Assess for contraindications or cautions: any
known allergies to these
to avoid hypersensitivity
reactions
; presence of bradycardia or heart blocks,
which could be worsened by the slowing of heart
rate and conduction
; asthma or bronchospasm,
which could be exacerbated by the loss of the
bronchodilation effect of noradrenaline
; shock
or HF,
which could worsen with the loss of the
sympathetic reaction
; diabetes,
which could be
aggravated by the blocking of the sympathetic
response and the masking of the usual signs and
symptoms of hypoglycaemia and hyperglycaemia
;
and pregnancy or breastfeeding status
because
of the potential adverse effects on the fetus or
neonate.
■
■
Perform a physical assessment
to establish baseline
data for determining the effectiveness of the
drug and the occurrence of any adverse effects
associated with drug therapy
; assess the level of
orientation and for any complaints of dizziness,
paraesthesias or vertigo.
■
■
Monitor vital signs and assess cardiovascular
status, including pulse, blood pressure and cardiac
output,
to evaluate for possible cardiac effects
;
obtain an electrocardiogram (ECG) as ordered
to
assess for possible irregularities in rate or rhythm
;
assess respiratory rate and auscultate lungs
to
determine the presence of any adventitious sounds
;
observe for ease of breathing, and report any signs
and symptoms of bronchospasm or respiratory
distress; and monitor GI activity
to determine
the need for interventions to deal with increased
activity.
■
■
Monitor the results of laboratory tests such as renal
and liver function studies and electrolyte levels
to
determine the need for possible dose adjustment
;
monitor blood glucose levels
to evaluate for hyper-
or hypoglycaemia.
Implementation with rationale
■
■
Do not discontinue abruptly after chronic therapy
because hypersensitivity to catecholamines
may develop and the person could have a
severe reaction
; taper drug slowly over 2 weeks,
monitoring the person.
■
■
Consult with the doctor about withdrawing
the drug before surgery
because withdrawal is
controversial; effects on the sympathetic system
after surgery can cause problems.
■
■
Encourage the person to adopt lifestyle changes,
including diet, exercise, smoking cessation and
stress reduction,
to aid in lowering blood pressure.
■
■
Assess heart rate
for changes that might suggest
arrhythmias.
Obtain blood pressure in various
positions
to assess for orthostatic hypotension.
■
■
Institute safety precautions especially if the person
complains of dizziness, fatigue or vertigo or if
orthostatic hypotension occurs
to prevent injury to
the person.
■
■
Monitor GI function and need for increased access
to bathroom facilities and need for increased fluid
intake
related to diarrhoea.
■
■
Monitor for any sign of liver failure
to arrange to
discontinue the drug if this occurs
(this effect is
more likely to happen with carvedilol).
■
■
Offer support and encouragement
to help the
person deal with the drug regimen.
■
■
Provide thorough teaching, including drug name,
dosage and schedule for administration; measures
to prevent adverse effects and warning signs of
problems; the need to avoid herbal or alternative
therapies unless allowed by the prescriber; and
safety measures, such as changing position slowly
and avoiding driving or operating hazardous
machinery; and the need for monitoring and
evaluation
to enhance knowledge about drug
therapy and to promote compliance.
Evaluation
■
■
Monitor response to the drug (improvement in
blood pressure and HF).
■
■
Monitor for adverse effects (CV changes, headache,
GI upset, bronchospasm, liver failure).
■
■
Evaluate the effectiveness of the teaching plan
(person can name drug, dosage, adverse effects
to watch for, specific measures to avoid adverse
effects).
■
■
Monitor the effectiveness of comfort measures and
compliance with the regimen.
