For adults, BLS demands the coordinated execution of multiple tasks. One-rescuer CPR was the primary focus in earlier versions of BLS. Oftentimes, two or more people are on hand to perform CPR. In this carefully studied method, chest compressions, securing rescue breaths, directing the airway, and using the AED are all important actions that are done together by a team. With these synchronized efforts, several rescuers can shave off critical seconds of lost time, where each valuable second adds damage to the heart and brain.