ECG Changes by Severity
| Potassium (approx.) | ECG findings |
|---|---|
| 5.5-6.5 mEq/L | Peaked T waves |
| 6.5-7.5 mEq/L | Widened QRS, flattened or absent P waves |
| >7.5 mEq/L | Sine wave pattern — risk of VF or asystole |
These thresholds are approximate, not absolute — treat based on the ECG and clinical picture, not the number alone.
Treatment Steps, in Order
- Stop causative drugs (ACEi/ARB, potassium-sparing diuretics, NSAIDs, trimethoprim)
- If ECG changes are present or K+ is 6.5 or higher: IV calcium gluconate first — stabilizes the cardiac membrane (it doesn't lower potassium, it buys time)
- IV insulin with dextrose, and/or nebulized salbutamol — shifts potassium into cells (effect in roughly 30-60 minutes)
- IV sodium bicarbonate if significant acidosis is present
- Remove potassium from the body: loop diuretics if renal function allows, or dialysis if severe, refractory, or in renal failure
- Continuous cardiac monitoring throughout
Emergency Protocol
Treat any ECG change from hyperkalemia as a medical emergency — don't wait for repeat labs before giving calcium if ECG changes are present. Call for senior or critical care support early if potassium is very high or the patient is unstable, and recheck potassium and the ECG after each step.