ACLS Algorithms Review: Adult BLS Algorithm

A quick review of the Adult BLS Algorithm to study before taking your ACLS test.


While the Adult BLS Algorithm is classified as a Basic Life Support (BLS) algorithm, it is undoubtedly an algorithm you need to be familiar with in order to pass your Advanced Cardiac Life Support (ACLS) exam. This is because there is a relatively high degree of carry-over between the two courses. Thus, it’s important to know the BLS steps in sequence to improve your odds of passing your ACLS test.

BLS emphasizes early CPR and defibrillation using an AED. The primary goal of the Adult BLS Algorithm is to improve the chances of survival by ensuring adequate oxygenation, ventilation, and circulation. The Adult BLS Algorithm provides the necessary steps for both single-rescuer and multiple rescuer scenarios of an unresponsive adult. But you might still be wondering, what are the steps I need to know? And how are all these steps connected?

What are the BLS steps used for adults?

Lay people and first-time trainees may ask themselves: what is the difference between BLS and CPR? And the answer is simple, generally speaking, BLS is advanced CPR and AED care provided by healthcare workers. The steps, in turn, are similar to those in CPR, with the new BLS guidelines focusing on the rate and depth of compressions (100-120 per minute, 2-2.4 inches deep) defibrillation, and the use of one-way valve barrier devices for rescue breathing.

For detailed information, refer to the Adult BLS Algorithm below:

Adult BLS Algorithm

Before beginning:

Check for scene safety and victim responsiveness. Call for emergency medical help, and if available, bring an AED to the patient. If the patient has a normal pulse and is breathing normally, stay with the patient, and monitor their condition until the arrival of emergency medical services.

1. Circulation:

Check the patient for a pulse:

  • If no pulse is detected, begin delivering CPR. Place palms in the center of patients chest with one hand over the other and with arms locked, allowing the chest to fully rise between compressions, push down hard and fast to a depth of 2-2.4 inches at a rate of 100-120 compressions per minute (30 every 15-18 seconds) giving 2 rescue breaths for every 30 compressions.
  • If a pulse is detected, move to the airway section of the algorithm

2. Airways:

  • If the patient is breathing adequately, maintain the patient’s airway, and place them in the recovery position.
  • If you witnessed the collapse and can safely assume there is no spine injury, perform the chin lift maneuver to open the airway.
  • If you did not witness the collapse or the collapse was caused by trauma, use the jaw thrust method.
  • If a foreign object is blocking the airway remove the object either by inserting a finger into the mouth and scooping it out if easily accessible, otherwise perform abdominal thrusts to clear the obstruction.

3. Breathing:

Breathing regularity should be first assessed while assessing responsiveness and should be monitored throughout care, always use a barrier device when available.

  • If the patient has a pulse, begin rescue breathing immediately. If no CPR is required perform one rescue breath every six seconds (10 breaths per minute), and check pulse every two minutes.
  • If the patient has no pulse, and rescue breathing is part of CPR, ensure a good seal over the patient's mouth with either your mouth or barrier device, pinch their nose closed, and deliver one-second-long rescue breaths ensuring the chest rises and falls with each breath.

4. Defibrillate:

When the Automated External Defibrillator (AED) arrives, turn on the unit and follow the verbal prompts, firmly attach the fads to the patient's chest, and allow the AED to analyze the patient's heart rhythm.

  • If shock is required, ensure all responders have hands clear from the patient to avoid shocks before administering shock. Press the shock button when all hands are clear. After the shock has been administered, resume delivery of CPR.
  • If AED determines against shock, initiate CPR and recheck rhythm after 5 cycles.

Additional ACLS Algorithms:

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