What ECG finding would confirm suspicion of hyperkalemia in a patient experiencing cardiac arrest?

The presence of a wide-complex ventricular rhythm coupled with tall, peaked T waves is a classic ECG finding indicative of hyperkalemia, particularly in the context of cardiac arrest. Hyperkalemia leads to an increase in extracellular potassium concentration, which directly affects myocardial depolarization and repolarization processes.

Typically, tall, peaked T waves represent early signs of hyperkalemia as elevated potassium levels alter the action potential duration and affect the repolarization phase of cardiac cells. As hyperkalemia worsens, it can lead to further changes such as widening of the QRS complexes and potentially progress to ventricular fibrillation or asystole, which is why a wide-complex ventricular rhythm is observed in advanced cases. This ECG finding is especially critical in emergency settings because it helps identify a reversible cause of cardiac arrest, allowing for timely intervention, such as the administration of calcium, insulin, or other treatments to stabilize the myocardium and shift potassium back into cells.

In contrast, narrow QRS complexes typically indicate normal conduction without significant electrolyte disturbance, while a normal sinus rhythm would not suggest hyperkalemia at all. Bradycardia with an AV block can occur in various cardiac conditions, but it does not specifically indicate hyperkalemia as potently as the combination