During a transport of cardiac arrest victim whom you have revived, his heart stops beating again. after confirming he is pulseless, you should immediately:

The very first thing to don is to direct your partner to stop the vehicle.  if the patient goes into cardiac arrest during transport you should have your partner stop the vehicle and come back to assist you. the vehicle must not be moving to initiate an (automated external defibrillator)  aed analyze mode. your focus should be on delivery of an aed shock as soon as possible. while the vehicle is stopping, you should then initiate cpr.