A 70-year-old woman is brought to the emergency department by ambulance. She was found on the floor of her apartment after her neighbor called 911. She is confused and is unable to provide any history, but complains of generalized pain. Her temperature is 99.2°F (37.3°C), blood pressure is 129/64 mmHg, pulse is 63/min, respirations are 13/min, and oxygen saturation is 99% on room air. Physical exam reveals, a confused, ill-appearing woman. Lungs are clear to auscultation bilaterally. An electrocardiogram is obtained as shown in Figure A. Dipstick urinalysis is notable for 4+ blood and dark colored urine. Which of the following is the most appropriate next step in management?
Albuterol and IV fluid resuscitation
Calcium gluconate
IV fluid resuscitation
Sodium polystyrene sulfonate
Calcium gluconate
This patient with confusion, dark urine, and peaked T waves on electrocardiogram in the setting of a prolonged time spent down likely has developed rhabdomyolysis with associated hyperkalemia. For patients with suspected hyperkalemia and electrocardiogram changes, the most appropriate next step in management is treatment with calcium gluconate

Rhabdomyolysis occurs when muscle cells lyse and release their intracellular contents. This can occur secondary to intense athletics, seizures, stimulant drug use, or a prolonged period of immobility. Lysis of muscle cells leads to release of potassium, myoglobin, purines, and other intracellular contents. Release of large amounts of myoglobin can result in renal impairment and myoglobinuria. On dipstick urinalysis, myoglobin causes a positive result for blood. Renal impairment further increases the risk for development of hyperkalemia. On ECG, hyperkalemia manifests with a "peaked" appearance of T waves, especially in the precordial leads. As hyperkalemia worsens, electrocardiogram changes progress to loss of P waves, QRS complex widening, and eventual sine wave rhythm. For patients with suspected hyperkalemia and characteristic changes noted on the electrocardiogram, the most appropriate immediate step in management is treatment with intravenous calcium gluconate. Calcium gluconate acts to stabilize cardiac myocyte membranes and prevent development of life-threatening arrhythmias.

Gupta et. al review rhabdomyolysis. They discuss the pathophysiology, clinical manifestations and diagnosis. They further detail complications that may arise such as hyperkalemia, and discuss respective management strategies.

Figure A demonstrates an electrocardiogram with features characteristic of hyperkalemia. Note the peaked appearance of the T waves in the precordial leads.

Incorrect Answers:
Answer A: Albuterol and IV fluid resuscitation may eventually be appropriate. Albuterol (a beta agonist) will act to shift potassium to the intracellular compartment. This patient's electrocardiogram changes warrant immediate treatment with calcium gluconate in order to stabilize cardiac myocyte membranes.

Answer C: Insulin, glucose, and IV fluid resuscitation are indicated in this patient. Insulin acts to shift potassium to the intracellular compartment, and fluid resuscitation is warranted for the patient's likely renal impairment. Calcium gluconate is the more immediate priority to prevent development of arrhythmia.

Answer D: IV fluid resuscitation is indicated for this patient with likely renal impairment. However, calcium gluconate is the more immediate priority to address this patient's hyperkalemia and prevent development of arrhythmia.

Answer E: Sodium polystyrene is an oral potassium binder that increases GI excretion of potassium. It may be appropriate to treat mild hyperkalemia in some patients. It takes a prolonged amount of time to have any significant effect.

Bullet Summary:
For patients with suspected hyperkalemia and characteristic changes noted on ECG, the most appropriate immediate step in management is treatment with intravenous calcium gluconate.