Final answer:
Broad and flattened P waves in severe hyperkalemia may precede arrhythmias or cardiac arrest due to disturbed atrial depolarization and impaired myocardial repolarization, necessitating urgent treatment.
Step-by-step explanation:
In the context of severe hyperkalemia, broad and flattened P waves on an electrocardiogram (ECG) may precede serious cardiac events such as arrhythmias or even cardiac arrest. Hyperkalemia can cause a range of ECG changes due to its effect on myocardial membrane potentials, including peaked T waves, prolonged PR interval, and broadened QRS complexes. In extreme cases, it can lead to a sine wave pattern followed by asystole. The broad and flattened P waves are indicative of atrial depolarization disturbances and are an alarming sign suggesting that the myocardium may be unable to repolarize efficiently. Immediate treatment to normalize potassium levels is critical to prevent fatal outcomes.