A 60-year-old woman is brought to the emergency department after an episode of syncope. She also has generalized weakness and mild nausea. The patient was recently hospitalized for acute decompensated heart failure, and her left ventricular ejection fraction was estimated at 35% by echocardiography. Her discharge medications include furosemide, carvedilol, lisinopril, aspirin, and atorvastatin. At her outpatient visit a week ago, her lisinopril dose was increased and she was started on spironolactone.
Her temperature is 36.8 C (98.2 F) , blood pressure is 120/82 mm Hg, pulse is 74/min, and respirations are 16/min. Pulse oximetry is 95% on room air. Jugular venous pressure is 8 cm H₂O. Scattered bibasilar crackles are present. The patient has a grade 2/6 systolic ejection murmur along the right sternal border without radiation. She has 1+ pedal edema to the knees bilaterally.
Her ECG shows no P waves and a wide complex regular rhythm at 74/min. ECG done a week ago showed normal sinus rhythm, narrow QRS complexes (90 msec) , and non-specific T wave abnormalities.
The patient would most likely benefit from which of the following?

Question

Quizplus · Accepted Answer

11ec193a_95b3_f917_853d_b1a42a82303c_MD0002_00 This patient most likely has significant hyperkalemia, as suggested by a wide complex regular rhythm with no P waves. The combined effect of lisinopril (decreases aldosterone formation) and spironolactone (antagonizes aldosterone action) likely led to this patient's hyperkalemia. It is recommended that this combination therapy be used only in patients with an estimated glomerular filtration rate >30 mL/min, and serum potassium should be monitored closely. Patients with significant hyperkalemia and cardiac arrhythmias (not just isolated peaked T waves) should receive emergent therapy with intravenous calcium gluconate, which raises the cardiac resting potential and is the quickest way to antagonize the cell membrane effects of hyperkalemia. Other therapies include insulin plus glucose and β-2 agonists (eg, albuterol) to drive potassium into cells. (Choice A) Amiodarone is indicated for the control of recurrent ventricular fibrillation, hemodynamically unstable ventricular tachycardia, atrial fibrillation, and narrow QRS complex tachycardia. However, this patient's ECG is not consistent with any of these rhythms. (Choice B) Atropine is indicated in certain cases of symptomatic bradycardia and atrioventricular nodal block. However, atropine is not effective in treating the acute ECG changes of hyperkalemia. (Choice D) Furosemide takes time to induce diuresis and reduce hyperkalemia. As a result, it should not be used as emergency therapy for life-threatening hyperkalemia. (Choice E) Beta agonists (not beta blockers) are used in the treatment of hyperkalemia. Educational objective: Patients with hyperkalemia and significant abnormalities on ECG should receive intravenous calcium gluconate to rapidly antagonize the cell membrane effects of potassium. The hyperkalemia can then be corrected with β-2 agonists and/or insulin plus glucose. __________ References: Emergency interventions for hyperkalaemia. (http://www.ncbi.nlm.nih.gov/pubmed/15846652)

A 60-Year-Old Woman Is Brought to the Emergency Department After