Three Days After an Anterior Wall MI,a Patient Is in the Critical

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