CCRN Drugs Review Questions with Detailed Answers

Dobutamine Mechanism of Action Dobutamine, a racemic mixture, stimulates myocardial beta1-adrenergic receptors, resulting in increased contractility and heart rate, and stimulates both beta2- and alpha1-receptors in the vasculature. Although beta2 and alpha1 adrenergic receptors are also activated, the effects of beta2 receptor activation may equally offset or be slightly greater than the effects of alpha1 stimulation, resulting in some vasodilation in addition to the inotropic and chronotropic actions Beta 1 agonist/inotrope, with little beta II stimulation Dose: 0.5-0.1 mcg/kg/min Nitroprusside Mechanism of Action Causes peripheral vasodilation by direct action on venous and arteriolar smooth muscle, thus reducing peripheral resistance; will increase cardiac output by decreasing afterload; reduces aortal and left ventricular impedance Kerley B Lines Lines found in the lower peripheral zone of the Chest xray, caused by pulmonary edema and mycoplasma edema Normal BNP Less than 100 pg/mL Normal Pulmonary Occlusive Wedge Pressure 8-12, 18 = LV failure -measurement of left ventricular preload Normal CVP 0-5 10 = RV failure Dopamine 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 Stroke Volume 50-100 ml/beat Cardiac Index 2.5-4 l/min/m PAOP 8-12 mm hg Serum Lactate Measure of tissue hypoxia Normal levels 1-2 mmoles Normal MAP 70-110 mm hg SVR 900-1300 dynes/sec/cm