Dopamine is a frequently used drug in critically ill patient

Discussion in 'MRCS Forum' started by Lona., Nov 28, 2007.

  1. Lona.

    Lona. Guest

    Dopamine is a frequently used drug in critically ill patients because -
    a- At a high doses it increases splanchnic flow
    b- At high doses it increases coronary flow
    c- At low doses it decreases heart rate
    d- At low doses it lowers peripheral resistance
    e- It inhibits catecholamine release
  2. Lona.

    Lona. Guest

    Answer: B. (Schwartz, 7/e, pp 454-455) Dopamine has a variety of pharmacologic characteristics that make it useful in critically ill patients. In low doses [1 to 5 mg/(kg.min)], dopamine affects primarily the dopamonergic receptors. Activation of these receptors causes vasodilation of the renal and mesenteric vasculature and mild vasoconstriction of the peripheral bed, which thereby redirects blood flow to kidneys and bowel. At these low doses, the net effect on the overall vascular resistance may be slight. As the dose rises [2 to 10 mg/(kg.min)], β1-receptor activity predominates and the inotropic effect on the myocardium leads to increased cardiac output and blood pressure. Above 10 mg/(kg.min), α-receptor stimulation causes peripheral vasoconstriction, shifting of blood from extremities to organs, decreased kidney function and hypertension. At all doses, the diastolic blood pressure can be expected to rise; since coronary perfusion is largely a result of the head of pressure at the coronary ostia, coronary blood flow should be increased.

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