BLS Algorithm
The BLS algorithm is the sequence a healthcare provider follows when someone may be in cardiac arrest. It is what an AHA BLS course trains and tests. This guide sets out the steps in plain language; the course teaches them on manikins, and the published AHA guidelines are the authoritative version.
The core sequence
Check the scene is safe → check responsiveness → shout for help and get an AED → check breathing and pulse together for no more than 10 seconds → if no pulse, start CPR with compressions → use the AED as soon as it arrives → continue until help takes over or the person recovers.
The sequence is the same, with three important differences. The depth is about one third of the chest: about 5 cm for a child and about 4 cm for an infant. The technique changes: one or two hands for a child; for an infant, two fingers or the heel of one hand for a single rescuer, and the two-thumb encircling-hands technique for two rescuers. And the ratio changes to 15 compressions to 2 breaths when two rescuers are present. For an unwitnessed collapse of a child or infant when you are alone, giving about two minutes of CPR before leaving to call for help is part of the sequence.
With two or more rescuers, one gives compressions and the other manages breaths with a bag-mask device, swapping every 2 minutes. In a hospital, BLS runs underneath the advanced team — which is where the ACLS algorithms take over. See BLS vs ACLS for how the two fit together.
BLS also covers choking relief: abdominal thrusts for a responsive adult or child, back blows and chest thrusts for an infant, and CPR if the person becomes unresponsive.
Reading the steps is not the same as doing them. The BLS course is where you practise them until they are automatic, and the skills test is where you show you can.
Other life support and first aid courses: ACLS Course · PALS Course · First Aid Course · Training calendar
30:2 for adults, and for children and infants with a single rescuer. 15:2 for children and infants when two rescuers are present.
At least 5 cm for an adult, avoiding more than 6 cm; about 5 cm for a child and about 4 cm for an infant, roughly one third of the chest depth.
No more than 10 seconds, checking breathing at the same time.
As soon as it arrives. Turn it on and follow the prompts, then resume compressions immediately after any shock.
In the American Heart Association CPR and ECC Guidelines, linked in the sources below.
Safety First Medical Services is an American Heart Association training centre on Al Reem Island. Classroom BLS, HeartCode blended BLS and on-site group BLS training, with a two-year AHA BLS Provider eCard on completion.
See BLS dates and register HeartCode BLS course page Group booking enquiry
What we teach follows the awarding body and the UAE health authorities. For the definitive position on a course or licensing question, these are the places to check.
Last reviewed by the training team at Safety First Medical Services, an American Heart Association training centre at Addax Office Tower, Al Reem Island, Abu Dhabi. Call +971 55 761 9841 or email training@safetyfirstmed.ae.