ECGs
Traditional teaching of the ECG changes in hyperkalaemia lists the following in chronological order [4]:
- Peaking of T waves (repolarisation abnormalities – Fig.1)
- Shortening of the PR interval (progressive atrial paralysis)
- Prolongation of the QRS complex (conduction abnormalities – Fig.2)
- Flattening of the P wave
- Bradycardia
- “Sine wave” rhythm (a pre-terminal rhythm – Fig.3)
- Asystole
Fig.1
Fig.2
Fig.3
Reference: Life in the Fast Lane ECG Library
It is important to note, however, that ECG changes only occur in around 50% of patients with hyperkalaemia [5], and that the ECG alone is not an adequate predictor of the severity of hyperkalaemia.