Management of ECG Changes in Hyperkalemia
Immediately administer intravenous calcium gluconate (10%) 15-30 mL over 2-5 minutes or calcium chloride (10%) 5-10 mL over 2-5 minutes as first-line treatment when any ECG changes from hyperkalemia are present, as this stabilizes the cardiac membrane within 1-3 minutes and prevents life-threatening arrhythmias. 1, 2
ECG Changes Progress Predictably with Rising Potassium
The ECG manifestations of hyperkalemia follow a characteristic sequence that correlates with worsening cardiotoxicity 1, 2:
- Peaked/tented T waves (earliest finding, typically K+ >5.5 mEq/L) 1
- Flattened or absent P waves with prolonged PR interval 1, 2
- Widened QRS complex with deepened S waves 1
- Sine-wave pattern (merging of S and T waves, "tombstone" pattern) 1, 2
- Ventricular fibrillation or asystolic cardiac arrest 1
Critical Caveat About ECG Sensitivity
ECG findings can be highly variable and are not as sensitive as laboratory testing in predicting hyperkalemia or its complications. 3 The absence of ECG changes does not rule out dangerous hyperkalemia, particularly in patients with chronic kidney disease, diabetes, or heart failure who may tolerate higher potassium levels without ECG manifestations 1. However, when ECG changes are present, they indicate severe cardiotoxicity requiring immediate intervention 1.
Treatment Algorithm for Hyperkalemia with ECG Changes
Step 1: Cardiac Membrane Stabilization (Acts in 1-3 Minutes)
Administer calcium immediately 3, 1, 2:
- Calcium gluconate 10%: 15-30 mL IV over 2-5 minutes 1, 2, 4
- OR calcium chloride 10%: 5-10 mL (500-1000 mg) IV over 2-5 minutes 1, 2
- If no effect within 5-10 minutes, repeat the dose 3, 2
- This does NOT lower serum potassium but antagonizes cardiac membrane effects 2
- Effect is temporary (30-60 minutes), so additional potassium-lowering measures must follow promptly 2
Important safety considerations for calcium administration 4:
- Avoid in patients on cardiac glycosides (digoxin) due to increased risk of arrhythmias and digoxin toxicity; if necessary, give slowly with close ECG monitoring 4
- Do not mix with ceftriaxone (contraindicated in neonates ≤28 days; can be given sequentially in older patients with line flushing) 4
- Do not mix with bicarbonate or phosphate-containing fluids 4
- Rapid administration can cause hypotension, bradycardia, and cardiac arrest; maximum rate 200 mg/minute in adults, 100 mg/minute in pediatrics 4
Step 2: Shift Potassium Intracellularly (Acts in 15-30 Minutes)
Inhaled beta-2 agonist 3, 1, 2:
Sodium bicarbonate (if metabolic acidosis present) 3, 1, 2:
- 50 mEq IV over 5 minutes 1, 2
- Promotes potassium excretion through increased distal sodium delivery 3
- Poor efficacy when used alone 5
Step 3: Remove Potassium from Body (Acts in Hours)
Diuretics (if adequate renal function) 3, 1, 2:
Cation exchange resin 3, 1, 2:
- For severe cases, especially with renal failure 2
- Use as adjunctive therapy after instituting other approaches 3
Special Clinical Scenarios
Patients with Chronic Hyperkalemia or Baseline ECG Abnormalities
Patients admitted with hyperkalemia may have ST segment elevation with peaked T waves and QRS widening as their admission "baseline." As hyperkalemia resolves and the ST segment returns to normal, this may trigger false ST segment alarms on continuous monitoring 3. Adjust alarm settings for the patient's new baseline during resolution to avoid unnecessary alarms 3.
Cardiac Arrest from Hyperkalemia
If cardiac arrest has occurred, continue standard ACLS protocols while simultaneously administering hyperkalemia-specific treatments 1.
Essential Monitoring and Follow-Up
- Continuous cardiac monitoring is essential during treatment 1, 2
- Verify hyperkalemia with a second sample when possible to rule out pseudohyperkalemia from hemolysis 2
- Monitor serum potassium every 4-6 hours during intermittent calcium infusions, every 1-4 hours during continuous infusion 4
Preventing Recurrence
After acute management, identify and address underlying causes 3: