What should you instruct a bystander performing CPR to do when you arrive?

When you arrive at a scene where a bystander is performing CPR, it is essential to ensure that high-quality CPR continues without interruption. The correct action in this situation is to instruct the bystander to continue CPR. This is because continuous chest compressions are crucial for maintaining blood circulation and oxygenation until professional help takes over.

Instructing the bystander to verify if the patient is pulseless is not the best action at this moment. The bystander, who is likely not trained professionally, may already be in a state of stress, and interrupting CPR for verification could lead to a loss of critical minutes. The focus should remain on sustaining life-saving efforts rather than reassessing the patient's condition.

Collecting a detailed history might be valuable later for medical responders, but it is not a priority when there is an active cardiac arrest situation. Keeping CPR ongoing is vital for maximizing the patient's chances of survival until advanced care can be provided.