Dopamine

Front 1

What is dopamine used for?

Back 1

Adjunct (something added on as extra) in the treatment of shock (eg, MI, open heart surgery, renal failure, cardiac decompensation, etc) which persists after adequate fluid volume replacement

Front 2

What are some warnings and precautions for dopamine?

Back 2

Warnings/Precautions

Use with caution in patients with
cardiovascular disease
cardiac arrhythmias

Correct hypovolemia and electrolytes when used in hemodynamic support.

May cause increases in HR and arrhythmia. Avoid infiltration - may cause severe tissue necrosis.

Use with caution in post-MI patients. Why?

Front 3

What are some adverse Reactions of Dopamine?

Back 3

Cardiovascular: Ectopic beats, tachycardia, anginal pain, palpitations, hypotension,
Infrequent: Aberrant conduction, bradycardia, piloerection, widened QRS complex, azotemia, elevated pressure, polyuria, dilated pupils, ventricular arrhythmias (high dose), gangrene (high dose), hypertension, azotemia, anxiety, elevations in serum glucose (usually not above normal limits); extravasation of dopamine can cause tissue necrosis and sloughing of surrounding tissues.

Front 4

What can happen with a dopamine over dose, what do you do in the case of a extravisation?

Back 4

Overdosage/Toxicology

Symptoms of overdose include severe hypertension, cardiac arrhythmias, acute renal failure
Important: Antidote for peripheral ischemia: To prevent sloughing and necrosis in ischemic areas, the area should be infiltrated as soon as possible with 10-15 mL of saline solution containing from 5-10 mg of Regitine® (brand of phentolamine), an adrenergic blocking agent. A syringe with a fine hypodermic needle should be used, and the solution liberally infiltrated throughout the ischemic area. Sympathetic blockade with phentolamine causes immediate and conspicuous local hyperemic changes if the area is infiltrated within 12 hours. Therefore, phentolamine should be given as soon as possible after the extravasation is noted.

Nursing Implications

Extravasation: Due to short half-life, withdrawal of drug is often only necessary treatment. Use phentolamine as antidote; mix 5 mg with 9 mL of NS; inject a small amount of this dilution into extravasated area; blanching should reverse immediately. Monitor site; if blanching should recur, additional injections of phentolamine may be needed.

Front 5

Drug interactions with Dopamine?

Back 5

Beta-blockers (nonselective ones) may increase hypertensive effect; avoid concurrent use.
Cocaine may cause malignant arrhythmias; avoid concurrent use.
Guanethidine's hypotensive effects may only be partially reversed; may need to use a direct-acting sympathomimetic.
MAO inhibitors potentiate hypertension and hypertensive crisis; avoid concurrent use.
Methyldopa can increase the pressor response; be aware of patient's drug regimen.
Reserpine increases the pressor response; be aware of patient's drug regimen.
TCAs increase the pressor response; be aware of patient's drug regimen.

Front 6

Mechanism of Action of Doapmine?

Back 6

Mechanism of Action

Stimulates both adrenergic and dopaminergic receptors, lower doses are mainly dopaminergic stimulating and produce renal and mesenteric vasodilation, higher doses also are both dopaminergic and beta1-adrenergic stimulating and produce cardiac stimulation and renal vasodilation; large doses stimulate alpha-adrenergic receptors

Front 7

What is the pharmacogynamics of dopamine?

Back 7

Children: With medication changes, may not achieve steady-state for ~1 hour rather than 20 minutes
Adults: Onset of action: 5 minutes; Duration: <10 minutes
Metabolism: In the plasma, kidneys, and liver 75% to inactive metabolites by monoamine oxidase and 25% to norepinephrine (active)
Half-life: 2 minutes
Elimination: Metabolites are excreted in urine; neonatal clearance varies and appears to be age related; clearance is more prolonged with combined hepatic and renal dysfunction
Dopamine has exhibited nonlinear kinetics in children

Front 8

What are the ususal dosages of Dopamine?

Back 8

Usual Dosage

I.V. infusion (administration requires the use of an infusion pump):
Children: 1-20 mcg/kg/minute, maximum: 50 mcg/kg/minute continuous infusion, titrate to desired response.
Adults: 1-5 mcg/kg/minute up to 50 mcg/kg/minute, titrate to desired response. Infusion may be increased by 1-4 mcg/kg/minute at 10- to 30-minute intervals until optimal response is obtained.
If dosages >20-30 mcg/kg/minute are needed, a more direct-acting pressor may be more beneficial (ie, epinephrine, norepinephrine).
The hemodynamic effects of dopamine are dose-dependent:
Low-dose: 1-3 mcg/kg/minute, increased renal blood flow and urine output
Intermediate-dose: 3-10 mcg/kg/minute, increased renal blood flow, heart rate, cardiac contractility, and cardiac output
High-dose: >10 mcg/kg/minute, alpha-adrenergic effects begin to predominate, vasoconstriction, increased blood pressure

Front 9

Cardiovascular considerations of dopamine?

Back 9

Dopamine is most frequently used for treatment of hypotension because of its peripheral vasoconstrictor action. In this regard, dopamine is often used together with dobutamine and minimizes hypotension secondary to dobutamine-induced vasodilation. Thus, pressure is maintained by increased cardiac output (from dobutamine) and vasoconstriction (by dopamine). It is critical neither dopamine nor dobutamine be used in patients in the absence of correcting any hypovolemia as a cause of hypotension.