From the Guidelines
A hyperkalemic emergency is defined as a serum potassium level above 6.5 mmol/L with ECG changes or above 7.0 mmol/L regardless of ECG findings, requiring immediate intervention. This definition is based on the most recent guidelines from the American Heart Association, as outlined in the 2020 guidelines for cardiopulmonary resuscitation and emergency cardiovascular care 1. The clinical signs associated with severe hyperkalemia include flaccid paralysis, paresthesia, depressed deep tendon reflexes, or shortness of breath, while early electrocardiographic signs include peaked T waves on the ECG followed by flattened or absent T waves, prolonged PR interval, widened QRS complex, deepened S waves, and merging of S and T waves.
Key Considerations
- The ECG changes associated with hyperkalemia can rapidly progress to life-threatening cardiac arrhythmias, including ventricular fibrillation and asystole 1.
- The dangerous ECG changes that signal imminent cardiac arrest include widened QRS complexes, flattened P waves, peaked T waves, and sine wave patterns, making rapid recognition and treatment essential to prevent mortality.
- Treatment should begin with calcium gluconate to stabilize cardiac membranes, followed by insulin with glucose to shift potassium intracellularly, and may also include sodium bicarbonate, loop diuretics, and potassium-binding resins.
Treatment Options
- Calcium gluconate 10% (10 mL IV over 2-3 minutes) to stabilize cardiac membranes
- Insulin (10 units regular insulin IV) with glucose (25-50g IV) to shift potassium intracellularly
- Sodium bicarbonate (50 mEq IV over 5 minutes) if acidosis is present
- Loop diuretics like furosemide (40-80 mg IV) to eliminate potassium through urine
- Sodium polystyrene sulfonate (15-30g orally or rectally) or patiromer (8.4g orally) to remove potassium via the gastrointestinal tract
- Hemodialysis for severe cases unresponsive to medical therapy 1.
From the Research
Definition of Hyperkalemic Emergency
- Hyperkalemia is a common electrolyte disorder that can result in morbidity and mortality if not managed appropriately 2.
- It is characterized by an elevation in extracellular fluid concentrations of potassium (K+) 2.
- Hyperkalemia can be deadly, and treatment requires specific measures including membrane stabilization, cellular shift, and excretion 2.
Threshold for Hyperkalemic Emergency
- Hyperkalemia is usually detected via serum clinical laboratory measurement, with a threshold of greater than 5.0-5.5 mmol/L 3.
- However, there is no consensus over the potassium threshold that warrants intervention or its treatment algorithm 4.
Clinical Presentation
- The presentation of hyperkalemia can range from being asymptomatic to deadly arrhythmias 3.
- The appearance of symptoms depends on the rate of change rather than just the numerical values 3.
- Rare presentations include periodic paralysis characterized by the sudden onset of short-term muscle weakness, stiffness, or paralysis 3.
Management of Hyperkalemic Emergency
- Management goals are directed towards reducing potassium levels in emergency settings and later on avoiding the triggers for future attacks 3.
- Treatment includes measures to "stabilize" cardiac membranes, to shift K+ from extracellular to intracellular stores, and to promote K+ excretion 2.
- Calcium gluconate 10% dosed 10 mL intravenously should be provided for membrane stabilization, unless the patient is in cardiac arrest, in which case 10 mL calcium chloride is warranted 2.
- Beta-agonists and intravenous insulin should be given, and some experts recommend the use of synthetic short-acting insulins rather than regular insulin 2.
- Dialysis is the most efficient means to enable removal of excess K+ 2, 5.
- Loop and thiazide diuretics can also be useful 2.
- Sodium polystyrene sulfonate is not efficacious 2.
- New medications to promote gastrointestinal K+ excretion, which include patiromer and sodium zirconium cyclosilicate, hold promise 2.