Q: The progression of EKG changes correlate well with the serum potassium concentration?
There are several EKG changes that occur with hyperkalemia. In early phases, the most well-known is a tall peaked T wave. The less known fact is that it should be read with a shortened QT interval. This is followed by progressive lengthening of the PR interval along with QRS duration. The disappearance of P-wave is relatively a late sign. QRS continues to widen and become a sine wave. This quickly degenerates into asystole.
Although above is the classic progress of EKG changes, hyperkalemia can be characterized by various other appearances on the EKG including bradycardia, idioventricular rhythms, V. Tach., V. Fib., pseudo-ST-elevations mimicking myocardial infarction, and pseudo-Brugada patterns.
The most important thing to remember is that an EKG change in hyperkalemia is an urgency to treat, as they do not correlate well with the serum potassium level.