During a procainamide infusion for atrial fibrillation, which change would indicate the need to stop the infusion?

The correct answer is related to the safety and monitoring considerations when administering procainamide, particularly in the context of atrial fibrillation management. Procainamide is an antiarrhythmic medication that can affect the cardiac conduction system, and it’s important to monitor for potential drug-induced toxicity.

An increase in the QRS duration indicates a delay in electrical conduction through the ventricles, which can lead to more serious arrhythmias or other cardiac complications. A QRS duration that exceeds a certain threshold (usually around 120-140 ms) while on procainamide suggests that the patient may be experiencing significant drug effects or toxicity. In this case, an increase to 126 ms would be cause for concern and indicate that the infusion should be stopped to prevent further cardiovascular complications.

Monitoring for blood pressure, QTc duration, and oxygen saturation is also crucial, but changes in these parameters may not necessitate an immediate stop of the infusion like a significant change in the QRS duration would. A blood pressure reading of 110/78 mm Hg is generally acceptable, an increase to a QTc duration of 448 ms is close to the threshold but not definitive for stopping treatment, and a drop in oxygen saturation to 94% may not be acute