When do you call for an amblance if someone has a cadiac arrest?

You should call for an ambulance immediately if someone is unresponsive and not breathing normally, as these are signs of cardiac arrest. If you are unsure, it's better to err on the side of caution and call for help. Additionally, if you witness someone collapse or experience severe chest pain or discomfort, call for an ambulance right away. Time is critical in these situations, so prompt action is essential.