Three days after an anterior wall MI, a patient is in the critical care unit.The patient is receiving oxygen at 4 L/min by nasal cannula; nitroglycerin paste, 1-inch q6h; and Lopressor 25 mg PO q12h.The monitor shows that the patient is beginning to have premature ventricular contractions (PVCs).Over the course of the next several hours, the PVCs increase in frequency to more than 15 per minute, with occasional runs of multifocal bigeminal PVCs.The patient's vital signs follow: heart rate, 84 beats/min; sinus rhythm with described PVCs; blood pressure, 124/68 mm Hg; respirations, 20 breaths/min; and SpO₂, 92%.Laboratory values are blood pH, 7.44; potassium, 4.4 mEq/L; and magnesium, 1.0 mEq/L.Which of the following, if ordered, would be inappropriate for this patient? A) Lidocaine 100 mg IV push B) Increase oxygen to 6 L/min by nasal cannula C) Potassium chloride 40 mEq in 250 mL 0.9% saline IV piggyback over a 4-hour period D) Magnesium sulfate 2 g IV piggyback over a 2-hour period

Question

Quizplus · Accepted Answer

PVCs are initially controlled by administering oxygen to reduce myocardial hypoxia and by correcting acid-base or electrolyte imbalances.In the setting of an acute myocardial infarction, premature ventricular contractions (PVCs)are pharmacologically treated if they have the following characteristics: frequent (>6/min), closely coupled (R-on-T phenomenon), multiform shapes, and occurrence in bursts of three or more, increasing the risk of sustained ventricular tachycardia.The potassium level is within normal limits and replacement is not warranted.All other interventions listed are appropriate for this patient.

Three Days After an Anterior Wall MI, a Patient Is