zaki
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A 52-year-old man with a history of a lateral wall myocardial infarction is admitted from the emergency room with an acute anteroseptal infarction. His pulse rate is 115/min and blood pressure is 88/60 mm Hg; his urine flow is only 15 mL/h. His skin is cool, and he is slightly confused. A third heart sound is heard at the apex. Bedside right-heart catheterization reveals the following: mean right atrial pressure, 5 mm Hg; right ventricular pressure, 29/5 mm Hg; pulmonary artery pressure, 20/10 mm Hg; and mean pulmonary artery occlusive (wedge) pressure, 9 mm Hg. Cardiac index is 2.7 L/min/m2.
The most important single step in his initial management is administration of:
A)Cardiac glycosides intravenously
b)A beta-adrenergic blocking agent intravenously to lower heart rate to below 100/min
(C) Fluid intravenously until pulmonary artery diastolic pressure reaches 14 to 18 mm Hg
(D) High-dose dopamine (25 mg/kg/min) to raise systolic blood pressure to 100 mm Hg
(E) Isoproterenol to increase cardiac output
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Maverick
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| usmlebuzz
Forum Elite
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(D) I guess :|
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ans is c
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| zaki
Forum Guru
Topics: 92
Posts: 398
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no more responses ???
well the answer is c
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Maverick
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| usmlebuzz
Forum Elite
Topics: 93
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can u explain why?
thanks
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| zaki
Forum Guru
Topics: 92
Posts: 398
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well ritu here is the explanation
This patient, with old and new myocardial infarctions, has decreased ventricular diastolic compliance and requires a higher-than-normal filling pressure to improve left ventricular function. The most important first step is administration of fluids to achieve optimal left ventricular filling pressures of 14 to 18 mm Hg. Administration of cardiac glycosides in this patient is not likely to be helpful and may increase ultimate infarct size by increasing myocardial oxygen demand. Although isoproterenol may raise cardiac output, it may, like cardiac glycosides, increase the eventual infarct size. In addition, because of its vasodilator effects, isoproterenol may worsen hypotension, and it may produce serious ventricular arrhythmias. Because dopamine in high doses leads to peripheral vasoconstriction, it would not be appropriate.
There is considerable evidence for a beneficial effect of acute intravenous administration of beta-adrenergic blocking agents in selected patients with acute myocardial infarction. In this patient, however, the sinus tachycardia is a manifestation of hypotension and low cardiac output. It would be inappropriate to attempt to lower the heart rate with beta-adrenergic blocking agents at this point in his managemet
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Maverick
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