ACLS draws heavily on Basic Life Support (BLS). In fact, it is assumed that all people who are pursuing ACLS will be competent in the techniques of BLS—so much so that it is considered a prerequisite to ACLS
The first step in any resuscitation is to make sure the rescuers (you!) and the victim are safe. Therefore, if your victim is in the middle of the highway or in a burning building, the first step is to move the victim to safety.
Assuming you and the victim are in a safe location, the next step is to assess whether the patient is responsiv
If patient is not responsive, move to BLS survey
If patient is responsive, move to ACLS survey