In assessing a 10-year-old child with wide-complex tachycardia, which intervention poses the greatest potential for harm?

In the context of treating a 10-year-old child with wide-complex tachycardia, the intervention that poses the greatest potential for harm is starting an IV line and administering amiodarone followed by procainamide. This is primarily due to the risk of significant side effects and complications associated with both medications, especially in a pediatric patient.

Amiodarone and procainamide can have serious cardiovascular side effects, such as hypotension, bradycardia, and even exacerbation of arrhythmias. In children, where dosing must be precise and the effects can vary widely, there is a heightened risk of adverse reactions, particularly if the child's hemodynamic status is already compromised due to the tachycardia. Furthermore, the use of combination antiarrhythmic drugs may lead to toxicities or drug-drug interactions that could further complicate the child's condition.

Other options, such as administering high-flow oxygen and obtaining a 12-lead ECG, are foundational interventions that provide immediate benefit without significant risk. Establishing IO access, administering a sedative, and cardioverting at a low energy level can be managed more safely when done appropriately with proper monitoring, making them less likely to cause harm in an acute scenario. Similarly