Avoid suxamethonium if K+ >5.5 mmol/L or renal failure with rising K+. Treat arrhythmias before induction when possible.
ECG progression
- Peaked T waves, prolonged PR
- Wide QRS, sine wave pattern
- VF/asystole if untreated
Perioperative causes
- Renal failure, rhabdomyolysis, tumour lysis
- Stored blood transfusion, acidosis
- Tourniquet release, reperfusion
Mild: 5.5 to 5.9
- Avoid suxamethonium
- Treat the cause
- Recheck, continue monitoring
Moderate: 6.0 to 6.4
- ECG and cardiac monitoring
- Insulin-glucose, salbutamol
- Delay non-urgent surgery
Severe: 6.5 or higher
- IV calcium if ECG changes
- Shift and remove K+
- Rocuronium not sux; renal review
Stabilise then lower K+
1
1. Confirm
Repeat sample excluding haemolysis. 12-lead ECG. ABG if acidosis suspected.
Repeat sample excluding haemolysis. 12-lead ECG. ABG if acidosis suspected.
↓
2
2. Stabilise membrane
IV calcium chloride/gluconate if ECG changes or severe hyperkalaemia.
IV calcium chloride/gluconate if ECG changes or severe hyperkalaemia.
↓
3
3. Shift K+
Insulin-dextrose, salbutamol nebuliser. Sodium bicarbonate if acidotic (specialist guidance).
Insulin-dextrose, salbutamol nebuliser. Sodium bicarbonate if acidotic (specialist guidance).
↓
4
4. Remove K+
Diuretics if volume tolerant, potassium binders, dialysis if refractory. Use rocuronium not sux for RSI if indicated.
Diuretics if volume tolerant, potassium binders, dialysis if refractory. Use rocuronium not sux for RSI if indicated.
Anaesthesia choices
- Rocuronium for relaxation if sux contraindicated
- Avoid depolarising block with high K+
Pitfalls
- Missing pseudohyperkalaemia (tight tourniquet sample)
- Inducing without treating ECG changes
MedPrep - www.medprep.uk - Educational revision aid only. Not clinical guidance. Doses are adult examples; check the BNF, current guidelines and local policy, and seek senior advice. Nov 2026