A lot depends upon how many people you've got. A lot of places would roll an ambulance (two man crew) and an engine company (four man crew). Other places just roll an ambulance and then would call for extra personal. An ambulance needs four people ideally for CPR -- driver, airway, compressions, and everything else.
But assuming a two man crew, I'd keep the person who is doing CPR to continue on compressions. The first step, however, is to confirm no pulse and also the person is not long dead. 9-1-1 tells people to do CPR and I've arrived on the scene to see a person performing CPR on someone who has post-mortem lividity.
Once we've confirmed no pulse, as I said, I'd have the person who was there continue compressions. One person would work on establishing and maintaining an airway. Once the airway is established, which would depend upon the certification of the EMT as to the type, the airway EMT would monitor compressions, while using a bag-value mask to administer high-flow oxygen.
Second person would hook up the monitor, and attempt defibrillation if indicated. If qualified, the EMT would then administer a large-bore IV, and use what drugs the protocols call for.
By this point, hopefully more manpower will have arrived, and we'd phase out the person doing compressions. The additional manpower would also start working on transport, using a backboard and strapping the patient to the backboard. Backboard would then be placed on a stretcher, if one can be used. Otherwise, we take the patient out of the house on the backboard. I've had to do this through a bedroom window because that was the easiest path. Compressions and oxygen continue throughout the trip to the ambulance.
Time on scene is going to be somewhere between three and ten minutes. We want to get going but some things can't be done easily in the ambulance and need to be done before we start transporting.
Jim Clark-Dawe