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Файл:Ординатура / Хирургия / Библиотека им академика М.И. Перельмана / Книга_3978_Библиотеки_им_академика_М_И_Перельмана
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49
alone or in combination with dobutamine). For patients with septic shock and
myocardial dysfunction, dobutamine can be added to norepinephrine or dopamine
for added inotropic support.
Although no single agent is universally superior in this setting, dobutamine’s
ease of use and better side-effect profi le, along with milrinone’s pharmacokinetic
considerations, render milrinone as a secondary agent. As is the case in heart failure,
concomitant vasopressor therapy may be necessary. In select situations, milrinone
and dobutamine may be used in combination when an adequate cardiac index can-
not be obtained with either agent alone.
An important consideration for use of milrinone over dobutamine in ADHF,
however, is for patients admitted on beta-blocker therapy. The use of a beta-agonist
with a beta-blocker would be largely counterproductive. In these cases, the use of
milrinone during titration or maintenance of beta-blocker therapy would be
preferred.
Despite the potentially more favorable hemodynamic profi le of milrinone than
dobutamine, clinical outcomes between the two agents have not differed.
2.4 Vasodilators and Antihypertensives
Vasodilators are used to treat hypertension, heart failure, and angina; however,
some vasodilators are better suited than others for these indications.
Dilation of arterial (resistance) vessels leads to a reduction in systemic vascular
resistance, which leads to a fall in arterial blood pressure. Dilation of venous
(capacitance) vessels decreases venous blood pressure. Vasodilators that act primar-
ily on resistance vessels (arterial dilators) are used for hypertension and heart fail-
ure, but not for angina because of refl ex cardiac stimulation. Venous dilators are
very effective for angina, and sometimes used for heart failure, but are not used as
primary therapy for hypertension. Most vasodilator drugs are mixed (or balanced)
vasodilators in that they dilate both arteries and veins; however, there are some very
Table 2.4 Inotropic agents
Drug
Dose HR MAP PCWP CO SVR
Adverse effects
Dobutamine 2.5–20 mcg/kg/min 0/+ 0 − + − Arrhythmogenic,
may potentiate
hypokalemia,
myocardial
ischemia,
hypotension/
vasodilation
Increase/decrease by
1 mcg/kg/min at intervals
no longer than Q 30 min
Titration parameter: CO
and CI
Milrinone 0.125–0.75 mcg/kg/min 0/+ 0/− − + − Arrhythmogenic,
thrombocytopenia,
myocardial
ischemia,
hypotension/
vasodilation
Increase/decrease by
minimum of 0.125 mcg/
kg/min at intervals no
longer than Q 6 h
Titration parameter: CO
and CI
+ increase, − decrease, 0 no change
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useful drugs that are highly selective for arterial or venous vasculature. Some
vasodilators, because of their mechanism of action, also have other important
actions that can in some cases enhance their therapeutic utility as vasodilators or
provide some additional therapeutic benefi t (Koda-Kimble 2006 ; Rhoney and
Peacock 2009 ).
The potential drawbacks of vasodilators include:
• Systemic vasodilation and arterial pressure reduction can lead to a baroreceptor-
mediated refl ex stimulation of the heart (increased heart rate and inotropy). This
increases oxygen demand, which is undesirable if the patient also has coronary
artery disease (Dipiro et al. 2002 ).
• Vasodilators can impair normal baroreceptor-mediated refl ex vasoconstriction
when a person stands up, which can lead to orthostatic hypotension and syncope
upon standing (Dipiro et al. 2002 ).
• Vasodilators can lead to renal retention of sodium and water, which increases
blood volume and cardiac output and thereby compensates for the reduced sys-
temic vascular resistance (Dipiro et al. 2002 ) (Tables 2.5 and 2.6 ).
2.5 Intravenous Antiarrhythmic Agents
The ultimate goal of antiarrhythmic therapy is to maintain normal rhythm and con-
duction in the heart. Antiarrhythmic drugs either decrease or increase conduction
velocity, alter the excitability of cardiac cells by changing the duration of the refrac-
tory period, or suppress abnormal automaticity. All antiarrhythmic drugs alter mem-
brane ion conduction, which in turn alters the shape of the cardiac action potential
(Thireau et al. 2011 ; Kowey 1998 ).
Antiarrhythmic medications are used to treat a wide range of cardiac dysrhyth-
mias. Drugs from all of the different classes of antiarrhythmics are, at times, clini-
cally indicated for use in treating atrial fi brillation, atrial fl utter, paroxysmal
supraventricular tachycardia, ventricular tachycardia, and occasionally premature
ectopic beats from either the atrium or the ventricle. The choice of antiarrhythmics
is generally based on the specifi c dysrhythmia or the overall threat to well-being
caused by the dysrhythmia (nuisance versus life or death), the underlying substrate
(presence or absence of structural heart disease), and the extent of the symptoms
associated with the dysrhythmia (Ganjehei et al. 2011 ; Thireau et al. 2011 ; Kowey
1998 ) (Table 2.7 ).
2.6 Analgesic Agents
Pain control in the critical care setting is often inadequate. Critically ill patients
may experience pain that is due to their underlying illness or injury and surgery or
the result of other nonsurgical interventions. Pain may also be the result of a variety
of noxious stimuli present in the critical care setting from monitoring (arterial cath-
eter, central venous catheter), therapeutic devices (ventilator), or routine nursing
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Table 2.5 Intravenous vasodilator and antihypertensive agents
Drug
Indication
Onset of
action Dosing
Comments
Esmolol Acute MI 1–5 min
IV bolus :
Duration: 15–30 min
SVT 500 mcg/kg over 1 min Short t½ life (2–9 min)
Atrial fi brillation and atrial
fl utter
Continuous infusion :
Contraindicated in cocaine toxicity (if used alone),
LVF, COPD/asthma, and high-grade heart block
Hypertensive urgency/
emergency
50–300 mcg/kg/min Hypotension, injection site pain, nausea, heart
block, heart failure
Titrate by 50 mcg/kg/min every 10 min
Titration parameter: SBP and HR
Hydralazine Hypertensive urgency/
emergency
10–30 min
IV bolus :
Duration: 2–4 h
10 mg IV push q4h prn Direct arteriolar vasodilator with little or no effect
on venous circulation
Max dose: 20 mg IV push q4h prn Palpitation, angina, fl ushing, tachycardia,
headache
Titration parameter: SBP
Labetalol Hypertensive urgency/
emergency
5–10 min
IV bolus :
Duration: 2–6 h
20 mg IV push over 2 min Combined beta- adrenergic (B1 and B2) and
alpha- adrenergic blocker
Repeat with 40–80 mg at 10 min
intervals up to 150 mg
Avoid use in patients with CHF exacerbation,
COPD/asthma, bradycardia/heart block
Continuous infusion :
Orthostatic hypotension, tingling sensation,
nausea, dizziness, nasal congestion
0.5–8 mg/min
Titrate by 0.5 mg every 4 h
Titration parameter: SBP and HR
(continued)
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Drug
Indication
Onset of
action Dosing
Comments
Nicardipine Hypertensive urgency/
emergency
5–10 min
Continuous infusion :
Does not depress LV function
2.5–15 mg/h Use with caution in heart block, recent MI, CVA,
renal failure
Titrate by 2.5 mg/h every 5–15 min to
Max dose of 15 mg/h
Hypotension, peripheral edema, tachyarrhythmia,
headache
Titration parameter: SBP Contraindicated in aortic stenosis; may reduce
myocardial oxygen balance
Nitroglycerin Antianginal for ischemic
pain
2–5 min
IV bolus :
Tolerance may occur within 24–48 h
AMI/CHF
12.5–25 mcg if no SL or spray given
No phosphodiesterase inhibitors within 24 h or
tadalafi l within 48 h
Hypertensive urgency with
ACS
Continuous infusion :
May increase ICP, use with caution in
hypertensive encephalopathy
5–300 mcg/min Hypotension, fl ushing, headache, dizziness
Titrate by 5–10 mcg/min every 5 min to
max of 300 mcg/min
Titration parameter: SBP and angina
Nitroprusside Hypertensive urgency/
emergency
Immediate
Continuous infusion :
When treatment is prolonged (>24–48 h) or when
renal insuffi ciency is present, risk of cyanide and
thiocyanate toxicity is increased
CHF (↓ afterload) 0.1–5 mcg/kg/min May cause hypotension, CO
2
retention
(max: 10 mcg/kg/min) Bradyarrhythmia, hypotension, palpitations,
tachyarrhythmia
Increase/decrease rate by minimum of
0.5 mcg/kg/min at intervals no longer
than Q 15 min
Titration parameter: SBP
Table 2.5 (continued)
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Table 2.6 Oral antihypertensive agents
Agent Usual dose/frequency
Comments/adverse effects
Diuretics
Thiazide Chlorothiazide (Diuril
®
) 250–500 mg BID Increased urination, dizziness, possible decrease in
potassium, photosensitivity, dehydration, increase in
calcium levels
Chlorthalidone (Hygroton
®
) 12.5–25 mg daily
Hydrochlorothiazide 12.5–50 mg daily
Indapamide (Lozol
®
) 1.25–2.5 mg daily
Metolazone (Zaroxolyn
®
) 2.5–10 mg daily or BID
Loop Bumetanide (Bumex
®
) 0.5–2 mg daily or BID
Ethacrynic acid (Edecrin
®
) 25–100 mg daily
Furosemide (Lasix
®
) 10–40 mg daily
Torsemide (Demadex
®
) 5–10 mg daily
Potassium sparing Eplerenone (Inspra
®
) 50–100 mg daily
Spironolactone (Aldactone
®
) 25–50 mg daily
Beta-adrenergic blocking
agents
Acebutolol (Sectral
®
) 25–100 mg daily Dizziness, fatigue, bradycardia, bronchoconstriction
(contraindicated in bronchospastic disease, i.e., asthma)
Atenolol (Tenormin
®
) 25–100 mg daily
Betaxolol (Kerlone
®
) 5–20 mg daily
Bisoprolol (Zebeta
®
) 2.5–10 mg daily
Carvedilol (Coreg
®
) 12.5–50 mg BID
Labetalol (Normodyne
®
) 200–800 mg BID
Metoprolol (Lopressor
®
) 50–100 mg daily or BID
Nadolol (Corgard
®
) 40–120 mg daily
Pindolol (Visken
®
) 10–40 mg BID
Propranolol (Inderal
®
) 10–120 mg BID
Timolol (Blocadren
®
) 20–40 BID
(continued)
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ACE inhibitors Benazepril (Lotensin
®
) 10–40 mg daily Nonproductive dry cough, taste disturbances, increased
potassium, rash
Captopril (Capoten
®
) 12.5–100 mg BID or TID
Enalapril (Vasotec
®
) 5–40 mg daily or BID
Fosinopril (Monopril
®
) 10–40 mg daily
Lisinopril (Zestril
®
) 5–40 mg daily
Moexipril (Univasc
®
) 7.5–30 mg daily
Perindopril (Aceon
®
) 4–8 mg daily
Quinapril (Accupril
®
) 10–80 mg daily
Ramipril (Altace
®
) 2.5–20 mg daily
Trandolapril (Mavik
®
) 1–4 mg daily
Angiotensin II receptor
antagonists
Candesartan (Atacand
®
) 8–32 mg daily Dizziness, diarrhea, cough (lower incidence than with
ACE inhibitors)
Eprosartan mesylate (Teveten
®
) 400–800 mg daily or BID
Irbesartan (Avapro
®
) 75–300 mg daily
Losartan (Cozaar
®
) 25–100 mg daily
Olmesartan (Benicar
®
) 20–40 daily
Telmisartan (Micardis
®
) 20–80 mg daily
Valsartan (Diovan
®
) 40–320 mg daily or BID
Agent Usual dose/frequency
Comments/adverse effects
Table 2.6 (continued)
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Calcium channel
blocking agents
Verapamil immediate release 80–320 mg BID or TID Constipation, bradycardia, heart block, headache,
bradyarrhythmia, peripheral edema, pharyngitis
Verapamil (Calan SR
®
) 120–240 mg daily or BID
Diltiazem immediate release 45–270 mg TID Nausea, headache, heart block, bradyarrhythmia,
peripheral edema, dizziness, fatigue
Diltiazem (Dilacor XR
®
) 180–360 mg daily
Amlodipine (Norvasc
®
) 2.5–10 mg daily Dizziness, headache, fl ushing, peripheral edema,
palpitations
Felodipine (Plendil
®
) 2.5–20 mg daily
Isradipine (Dynacirc
®
) 2.5–10 mg BID
Nicardipine (Cardene SR
®
) 60–120 mg BID
Nifedipine (Adalat CC
®
) 30–90 mg daily
Nisoldipine (Sular
®
) 10–40 mg daily
Peripheral
alpha
1
- antagonists
Prazosin (Minipress
®
) 1–10 mg BID First-dose syncope, drowsiness, dry mouth, blurred vision
Terazosin (Hytrin
®
) 1–10 mg daily or BID
Doxazosin (Cardura
®
) 1–16 mg daily
Central alpha
2
-agonists Clonidine (Catapres
®
) 0.1–0.6 mg BID Dry mouth, sedation, sexual dysfunction, depression
Methyldopa (Aldomet
®
) 250–500 mg TID
Arterial vasodilators Hydralazine (Apresoline
®
) 10–100 mg BID or QID Headache, fl uid retention, refl ex tachycardia
Minoxidil (Loniten
®
) 5–100 mg daily or BID
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Table 2.7 Intravenous antiarrhythmic agents
Drug
Indication Dosing
Comments/adverse effects
Adenosine SVT 6 mg IV rapidly over 1–3 s Must be administered rapidly
May repeat with 12 mg IVP up to
two more doses Q1–2 min PRN
Patients taking carbamazepine and dipyridamole or cardiac
transplant recipients: use initial dose of 3 mg
Flushing, chest discomfort, pain of head and neck region,
dyspnea, headache, dizziness
Amiodarone (Class III
agent)
Atrial fi brillation 150 mg IV push Hypotension when given IV push
VF 300 mg IV × 1 dose in 3–5 min Dose may be repeated PRN to a maximum of 2.2 g/24 h
Pulseless VT
IV bolus ( non - ACLS ):
Supplementary boluses of 150 mg can be repeated every
10 min as necessary for recurrent/resistant arrhythmias
VT with pulse 150 mg IV over 10 min, may repeat Many drug-drug interactions
Q10 min PRN Hypothyroidism, pulmonary fi brosis, hepatotoxicity, optic
neuritis, bradyarrhythmia, hypotension, photosensitivity
Continuous infusion :
1 mg/min IV × 6 h, then 0.5 mg/
min × 18 h
Atropine Bradycardia 0.5 mg IV and repeat every 3–5 min Cardiac dysrhythmia, raised intraocular pressure,
respiratory depression
Maximum dose: 3 mg
Diltiazem (Class IV
agent)
Atrial fi brillation
IV bolus :
Bradyarrhythmia, peripheral edema, dizziness, headache,
fatigue
SVT 0.25 mg/kg over 2 min
May repeat dose in 15–20 min at
0.35 mg/kg
Continuous infusion :
5–15 mg/h
Increase/decrease rate by minimum
of 2.5 mg/h at intervals no longer
than Q4 h to goal
Titration parameter: HR
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Epinephrine Pulseless VT or VF 1 mg IV and repeat every 3–5 min Palpitations, sweating, dizziness, headache, tremor
PEA 1 mg IV and repeat every 3–5 min
Asystole 1 mg IV and repeat every 3–5 min
Isoproterenol Symptomatic bradycardia
refractory torsades de pointes
unresponsive to magnesium
Continuous infusion :
Do not use for treatment of cardiac arrest
Beta-blocker overdose 2–10 mcg/min Do not give with epinephrine (can cause VF/VT)
Titration parameter: HR Syncope, tachyarrhythmia, confusion, headache, tremor
Lidocaine (Class Ib
agent)
Pulseless VT or VF
IV bolus :
Maximum cumulative dose: 3 mg/kg
Stable VT 1–1.5 mg/kg IV Decrease maintenance dose if impaired liver function or
left ventricular dysfunction
May repeat with 0.5–0.75 mg/kg Use with caution in hepatic dysfunction
Q5–10 min CNS toxicity: paresthesias, confusion, seizure, and tremors
Continuous infusion :
Bradyarrhythmia, hypotension, dizziness, headache,
lightheadedness, numbness, confusion, somnolence
1–4 mg/min (15–60 ml/h)
Magnesium Sulfate Pulseless VT or VF associated
with torsades de pointes
Cardiac arrest
Use with caution in renal failure
Ventricular arrhythmias due to
digitalis toxicity
1–2 g IV push Hypotension with rapid administration
Torsades de pointes
CNS depression, hyporefl exia, vasodilatation, respiratory
tract paralysis, heart block
1–2 g IV × 1 and follow with
0.5–1 g/h IV and titrate
Procainamide (Class
Ia agent)
Stable VT
Loading dose
Administer until arrhythmia is suppressed, hypotension
occurs, QRS widens >50 % from baseline, or total of
17 mg/kg has been given
Atrial fi brillation 20 mg/min Reduce dose for renal dysfunction
PSVT Max dose: 17 mg/kg Use with caution in renal insuffi ciency
Continuous infusion :
Rarely used due to its toxicity and fairly high risk of
inducing arrhythmias
1–4 mg/min Hypotension, dysrhythmia, agranulocytosis, bone marrow
depression, systemic lupus erythematosus
(continued)
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Table 2.7 (continued)
Drug
Indication Dosing
Comments/adverse effects
Vasopressin Pulseless VT, VF, or PEA 40 units IV push × 1 May replace fi rst or second dose of epinephrine in ACLS
algorithm
Asystole
Verapamil (Class IV
agent)
Alternate drug (after adenos-
ine) to terminate PSVT narrow
QRS
Acute rate control Maximum cumulative dose: 20 mg
Atrial fi brillation, atrial fl utter,
or multifocal atrial tachycardia
2.5–5 mg IV bolus over 2 min
(elderly patient: 3 min)
Do NOT use for wide QRS tachycardias or Wolff-
Parkinson-White syndrome
Repeat 5–10 mg Q15–30 min Hypotension, bradycardia/heart block with concurrent use
of beta-blockers (i.e., metoprolol), dizziness, headache
Alternative dosing Verapamil can worsen heart failure
5 mg bolus Q15 min
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