Final answer:
For 1 and 2 rescuer adult BLS, the first steps are to ensure scene safety, check for responsiveness, call for help if the victim is unresponsive, and initiate chest compressions following the 'CAB' sequence.
Step-by-step explanation:
In Basic Life Support (BLS) for adults, whether it is one rescuer or two, the first step is always to ensure the scene is safe for the rescuers and victim. Once safety is confirmed, check for responsiveness of the victim by tapping and shouting. If there is no response and the person is not breathing normally, call for help and initiate chest compressions as soon as possible. It is paramount to follow the 'CAB' sequence which stands for Compression, Airway, and Breathing; this means that chest compressions are prioritized before opening the airway and providing rescue breaths.
In cases where someone is drowning, the initial step before administering CPR is to remove the individual from the water to a stable ground. Emergency services should be contacted immediately if not done already, and CPR should be initiated following the aforementioned sequence. When performing CPR, remember to compress the chest at least 5 cm deep and at a rate of 100 compressions per minute, which can be timed to the beat of the song 'Staying Alive'. Continue CPR until professional medical assistance arrives or until the victim shows signs of recovery.