Table 1

Electrocardiographic manifestations of serum hyperkalaemia relative to serum potassium level

Serum potassium levelExpected ECG abnormality
Mild hyperkalaemia 5.5–6.5 mmol/lTall, peaked T-waves with narrow base
Moderate hyperkalaemia 6.5–8.0 mmol/lPeaked T-waves
Prolonged PR interval
Decreased amplitude of P-waves
Widening of QRS complex
Severe hyperkalaemia >8.0 mmol/lAbsence of P-wave
Progressive widening of QRS complex
Eventual “sine-wave” pattern, VF, asystole