Examkin

Question

Difficulty: MediumPharmacologic Interventions

A 6161-year-old man with end-stage renal disease presents to the emergency department with profound generalized weakness. He missed his last two scheduled hemodialysis sessions due to transportation issues. His pulse is 5252/min, blood pressure is 110/70110/70 mmHg, and respiratory rate is 1616/min. An electrocardiogram reveals prolonged PR intervals, widened QRS complexes, and tall, peaked T waves. Laboratory studies show a serum potassium level of 8.18.1 mEq/L.

Arrange the following pharmacologic interventions in the most appropriate physiological sequence for the acute management of this patient's condition.

  1. 1Intravenous calcium gluconate
  2. 2Intravenous regular insulin and 50% dextrose
  3. 3Oral sodium zirconium cyclosilicate

Answer

The correct sequence is: Intravenous calcium gluconate, followed by Intravenous regular insulin and 50% dextrose, followed by Oral sodium zirconium cyclosilicate.
The standard sequence for severe hyperkalemia is stabilize, shift, and remove. Calcium gluconate acts in 1-3 minutes to stabilize the myocardium. Insulin/dextrose acts in 10-20 minutes to shift potassium intracellularly. Sodium zirconium cyclosilicate acts over hours to remove potassium from the GI tract.

Step-by-Step Solution

1
Identify life-threatening hyperkalemia with cardiac toxicity.
Prioritize cardiac membrane stabilization as the immediate first step.
The patient has a potassium of 8.1 mEq/L with a widened QRS complex, indicating impending fatal arrhythmia (e.g., ventricular fibrillation). Intravenous calcium (gluconate or chloride) acts within minutes to raise the threshold potential, restoring normal resting membrane excitability without changing the serum potassium concentration.
2
Initiate temporary transcellular potassium shifts.
Administer intravenous regular insulin along with dextrose.
Once the heart is protected, the extracellular potassium level must be lowered rapidly. Insulin stimulates the Na+/K+-ATPase pump, shifting potassium into the cells. Dextrose is given concurrently to prevent iatrogenic hypoglycemia. This takes effect in 10 to 20 minutes and lasts for a few hours.
3
Promote total body potassium elimination.
Administer a gastrointestinal potassium binder such as sodium zirconium cyclosilicate.
Since insulin only hides potassium inside cells temporarily, potassium must ultimately be removed from the body. While arranging for emergent hemodialysis (the definitive treatment for an ESRD patient), administering an oral potassium binder initiates the slow process (onset >2 hours) of gastrointestinal potassium excretion.

Key Concept

The pharmacologic management of severe symptomatic hyperkalemia follows a strict three-step sequence: 1) stabilize the cardiac membrane with calcium, 2) temporarily shift potassium intracellularly with insulin/albuterol, and 3) permanently remove potassium from the body with binders, diuretics, or dialysis.
Estimated Time:1m 30s
Rate this question

Topics

Pharmacologic Interventions

More questions from this topic