Page 131 - Critical Care Nursing Demystified

116 CRITICAL CARE NURSING DeMYSTIFIED

TABLE 3–7 Drugs That Affect Contractility
Action Use Precautions
Decreased Contractility (Negative Inotropic Agents)
Beta-adrenergic Blocks the sympa- ACS, acute Right ventricular
blocking agents thetic response (fight hypertensive heart failure from
like metoprolol or flight; increased crisis, pulmonary HTN,
(Lopressor) or HR, BP, adrenaline in tachycardia heart block, and
atenolol (Cor- the system) Stable heart bradycardia
gard) or biso- Reduces cardiac failure and
prolol (Zebeta) remodeling and reduced ejec-
reduces dysrhyth- tion fractions
mias
Results in slower HR
and lowered BP
Calcium channel Decreases intracel- Tachycardia, Do not use in bra-
blockers like lular calcium in car- coronary artery dycardias or sick
verapamil diac muscle spasm, angina sinus syndrome;
(Calan) or dilti- Also reduces after- do not stop
azem (Cardizem) load abruptly. Assess
for hypotension
Dilates coronary and heart failure
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Increased Contractility (Positive Inotropic Agents)
Digoxin Decreases heart rate Fast Watch for signs of
as well as AV con- tachyarrhythmia digoxin toxicity,
duction which include
blurred or yellow
vision
Do not administer
if apical HR is < 60
Do not give if
patient is in heart
block
Observe and
replace potassium
level if < 4 mEq/L
Hold if digoxin
serum level is >1.5
Not indicated for
acute decompen-
sated heart failure