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Page: P - 14.1
I. Pharmacology and Actions
A. Dopamine is a chemical precursor of Epinephrine. It occurs naturally in man, and has both alpha- and beta-receptor stimulating actions, as well as action on specific dopaminergic receptors. At high doses, actions are very similar to those of norepinephrine. At lower dose levels, the differential effects allow cardiac stimulation and support of blood pressure without increasing oxygen demand and vasoconstricting vital organs. In general, the following actions are seen:
1. 1-2 mcg/kg/min -
dilates renal and mesenteric blood vessels (no effect on heart rate or blood
2. 2-10 mcg/kg/min - beta effects on heart usually increase cardiac output without increasing heart rate or blood pressure.
3. 10-20 mcg/kg/min - alpha peripheral effects cause peripheral vasoconstriction and increased blood pressure.
4. 20-40 mcg/kg/min - alpha effects reverse dilatation of renal and mesenteric vessels with resultant decreased flow.
II. Prehospital Indications
A. Cardiogenic Shock and Bradycardia with hypotension.
A. May induce
tachydysrhythmias, in which case infusion should be decreased or stopped.
B. At low doses, decreased BP may occur due to peripheral vasodilatation. Increasing infusion rate will correct this.
C. Should not be added to sodium bicarbonate or other alkaline solutions since dopamine will be inactivated at higher pH.
DOPAMINE IS CONTRAINDICATED IN HYPOVOLEMIC SHOCK
Pressor agents worsen tissue hypoxia in the presence of hypovolemia. Because even some cardiac patients may be hypovolemic from diuretics, damaged myocardium and poor intake, careful differentiation is necessary. Invasive monitoring is often the only way to differentiate forms of shock. Treatment with dopamine is therefore indicated in the field only in severely unstable patients with evidence of increased venous pressure.
B. Contraindicated in patients with a known pheochromocytoma (a tumor that actually produces epinephrine and norepinephrine).
V. Administration Guidelines
A. Post Medical Control Contact
1. Mix: 400 mg (2
ampules) in 250 ml D5W to produce concentration of 1600 mcg/ml. (Microdrip
administration set only.)
2. Adult and pediatric: IV infusion ONLY. Begin at 5 mcg/kg/min, titrated up to 20 mcg/kg/min, to maintain BP of 90 systolic
Page: P - 14.2
VI. Side Effects and Special Notes
A. Most common side effects include ectopic beats, nausea and vomiting. Angina has also been reported following treatment. Tachycardia and dysrhythmias occur, but are less likely than with older pressor agents.
B. Dopamine increases oxygen consumption of the heart, although to a lesser extent than other catecholamines. It should be reserved for patients with serious symptomatic hypotension NOT caused by hypovolemia.
C. Tissue extravasation at the IV site can cause skin sloughing due to vasoconstriction. Be sure to make Emergency Department personnel aware if there has been any extravasation of dopamine containing solutions so that proper treatment can be instituted.
D. Can cause hypertensive crisis in susceptible individuals.
E. Certain antidepressants potentiate the effects of this drug. Check for medications and contact medical control if other medications are being used.
A. Cardiogenic Shock
A. 400 mg in 250cc =
B. Divide patient's weight in half to find Kg's.
Multiply dose (mcg/min) x Kg (4 mcg/min x 100 Kg = 400 mcg/min needed)
1600 mcg/1ml: 400 mcg/x
1600 x = 400
x = .25cc x 60 gtts
= 15 gtts/min (of microdrip administration set)