Dopamine is preferred in treatment of shock because -
Ans. is 'a' i.e., Renal vasodilatory effect Dopamine in shock o In shock, the main problem is inadequate tissue perfusion, especially to the vital organs. This includes decreased renal perfusion, leading to decrease in urine output. o When the patient is being treated, main aim is to improve perfusion; not just to raise blood pressure. o Dopamine dilates the renal blood vessels and improves renal perfusion, therefore it is preferred in the shock. o However you should keep in mind that dopamine is preferred in shock due to this advantageous effect, i.e., renal venodilatory effect. But the primary mechanism of action which is responsible for the improvement in shock is positive chronotropic effect. o The primary defect is decreased cardiac output with inadequate tissue perfusion. o Therefore the primary mechanism of action of the drugs used in shock is to increase cardiac output by increasing the cardiac force of contraction (i.e., inotropic effect). o Dopamine has additional benefit, i.e., it dilates renal vessels. Therefore dopamine is preferred in shock. o From above discussion, you can understand that two question can be framed. (i) Primary mechanism of action of dopamine in shock --) Ionotropic effect (Cardiac stimulation/increased cardiac output). (ii) Dopamine is preferred in shock --) Because it has renal venodilatory effect. o Following statement will clear your doubt. "An advantage of using dopamine in the treatment of shock is that its inotropic action increases cardiac output while dilating renal blood vessels and thereby increasing renal blood flow" Modern pharmacology with clinical application. "Dopamine is used in cardiogenic shock. Dopamine is an effective inotropic agent that causes less increase in hea rate (less chronotropic effect)". Dopamine also promotes renal aerial dilatation; this may be useful in preserving renal function" ______________Goodman & Gilman.
Renal vasodilatory effect
Increased cardiac output
Peripheral vasoconstriction
Prolonged action