A 76-year-old woman is brought to the emergency department by ambulance due to confusion. Her husband says that she has metastatic esophageal cancer and has been unable to eat or drink for the last few days. Yesterday, she became increasingly lethargic, and today, she is hard to arouse. Temperature is 37.1 C (98.8 F), blood pressure is 80/30 mm Hg, pulse is 60/min, and respirations are 30/min. Pulse oximetry is 95% on room air. The patient appears lethargic but opens her eyes to verbal stimuli. Mucous membranes are dry. A peripheral IV is placed, laboratory studies are ordered, and intravenous fluids are started. An ECG tracing is shown in the exhibit. Which of the following is the best next step in management?

Question

A 76-year-old woman is brought to the emergency department by ambulance due to confusion.  Her husband says that she has metastatic esophageal cancer and has been unable to eat or drink for the last few days.  Yesterday, she became increasingly lethargic, and today, she is hard to arouse.  Temperature is 37.1 C (98.8 F), blood pressure is 80/30 mm Hg, pulse is 60/min, and respirations are 30/min.  Pulse oximetry is 95% on room air.  The patient appears lethargic but opens her eyes to verbal stimuli.  Mucous membranes are dry.  A peripheral IV is placed, laboratory studies are ordered, and intravenous fluids are started.  An ECG tracing is shown in the exhibit.  Which of the following is the best next step in management?

Quizplus · Accepted Answer

This patient with diminished food and water intake developed dry mucous membranes, hypotension, and confusion, indicating hypovolemic shock. Severe hypovolemia often causes significant electrolyte abnormalities (eg, hypernatremia/hyponatremia, hyperkalemia, metabolic acidosis) due to gastrointestinal electrolyte losses, increased antidiuretic hormone secretion, and/or acute kidney injury. In this case, the presence of no P waves and a sine wave pattern on ECG is consistent with hyperkalemic emergency. sine wave pattern Hyperkalemic emergency usually arises when serum potassium is >6.5 mEq/L; it is marked by altered repolarization of skeletal and cardiac muscle, which leads to lethargy, muscle weakness, cardiac arrhythmias, and/or progressive changes on ECG (eg, peaked T waves ? loss of P waves ? widened QRS ? sine wave pattern ? asystole). progressive changes on ECG Patients with hyperkalemia-induced ECG changes require urgent treatment with calcium gluconate to stabilize the cardiac membranes and insulin plus glucose to drive potassium into cells. This temporarily counters the cardiac abnormalities, which provides time for removal of potassium from the body via stool (eg, patiromer), urine (eg, furosemide), and/or blood (eg, hemodialysis). (Choices A and E) Patients with complete heart block who are bradycardic and hypotensive are treated with atropine; transcutaneous pacing is used for those who do not adequately respond. Because this patient's heart rate is normal, her hypotension is unlikely to significantly improve with atropine and transcutaneous pacing. In addition, the lack of P waves on ECG is highly suspicious for hyperkalemia; treatment with calcium gluconate and insulin plus glucose should be attempted prior to other therapies. (Choice C) Magnesium sulfate is used to treat torsade de pointes, which is a polymorphic ventricular tachycardia. polymorphic ventricular tachycardia (Choice D) Norepinephrine is a vasopressive agent that acts on beta-1 and alpha-1 adrenergic receptors. It is the first-line agent for septic shock recalcitrant to fluid resuscitation. This patient who has not had food or drink in several days is more likely to have hypovolemic shock; she should be treated with intravenous fluids, not norepinephrine. Educational objective: Hyperkalemic emergency causes characteristic, progressive changes on ECG (eg, peaked T waves ? loss of P waves ? widened QRS ? sine wave pattern ? asystole). Patients with hyperkalemia-induced ECG changes should be urgently treated with calcium gluconate to stabilize the cardiac membrane and insulin plus glucose to move potassium into cells. Longer-acting therapies to remove potassium from the body can then be administered.

A 76-Year-Old Woman Is Brought to the Emergency Department by Ambulance