BLS Algorithm for Adult Cardiac Arrest


Cardiac Arrest is the cessation of blood circulation due to absent or ineffective cardiac mechanical activity. Clinically, the patient is unresponsive, not breathing or only gasping, and there is no detectable pulse. In the event of an adult experiencing cardiac arrest, it's essential to take prompt action to restore proper breathing and blood flow.

As a medical professional, it is important to be familiar with the Basic Life Support algorithm for adult cardiac arrest. The symptoms of adult cardiac arrest involve unresponsiveness, lack of breathing or agonal breaths, and an absent or ineffective pulse. Cerebral hypoxia can lead to a loss of consciousness and difficulty breathing.

Here's a step-by-step approach to providing basic life-saving interventions based on the American Heart Association's Guidelines for Cardiopulmonary Resuscitation and Emergency Cardiovascular Care.

BLS Algorithm for Adult Cardiac Arrest
BLS Algorithm for Adult Cardiac Arrest

Ensure a Safe Scene

If you encounter an adult cardiac arrest patient lying on the ground, ensure that the environment is safe for you and the victim before providing Basic Life Support. Assess the scene to ensure it is safe for you to respond.


Check if the Adult patient is responsive

Shake the cardiac arrest victim's shoulder and ask loudly, "Are you okay?" Simultaneously, observe the chest and torso for movement and normal breathing. If the adult victim collapsed in your presence, assume cardiac arrest with a shockable rhythm. If you can access an Automated External Defibrillator quickly, you may leave the victim to call 911, retrieve the AED, and perform CPR for 2 minutes.


If there are 2 or more rescuers:

  • Rescuer 1 will stay with the victim.
  • Rescuer 2 will activate the Emergency Medical Services.
  • Rescuer 3 will retrieve an AED.


Assess the Patient and Check Pulse

Check the pulse of the adult cardiac arrest patient for 5-10 seconds.


If the adult victim has a pulse, provide adequate rescue breathing:

  • Give 10 rescue breaths per minute (1 breath every 6 seconds).
  • Recheck the victim's pulse every 2 minutes.


If the adult victim doesn't have a pulse: Begin CPR starting with chest compressions.


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Cardiopulmonary Resuscitation

If the adult victim does not have a pulse or the presence of one is uncertain, begin five cycles of CPR, beginning with chest compressions. Each cycle should consist of 30 compressions and two rescue breaths (30:2) delivered at a rate of 100–120 compressions per minute.


  • Standard CPR without an advanced airway: 6-8 rescue breaths per minute
  • Standard CPR with an advanced airway: 10 rescue breaths per minute
  • If the adult patient has a pulse and CPR is not required: Give 10 rescue breaths per minute


.ontinue performing Cardiopulmonary Resuscitation until the return of spontaneous circulation (ROSC) or until the termination of efforts.


High-Quality CPR includes

  • Minimal interruptions for ventilation
  • Compression rate: 100-120 compressions per minute
  • Compression Depth: 2–2.4 inches
  • 18 seconds per cycle
  • Allow for full chest recoil with each compression.
  • Avoid excessive ventilation
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Arrival of AED

Early use of an Automated External Defibrillator is the most important intervention for cardiac arrest survival and should be done as soon as possible. To utilize an Automated External Defibrillator:

1. Turn it on and follow the voice prompts.

2. Firmly place the adult pads on the patient's chest according to the pad image.

3. Allow the AED to analyze the rhythm.

  • If it is not shockable, administer CPR for two minutes, then recheck the rhythm every two minutes and continue CPR until Advanced Life Support becomes available.
  • If the shock is indicated, ensure that no one is touching the patient and shout, "Clear, I'm Clear, you're Clear!" before delivering the shock. Press the "shock" button once the rescuers and the surrounding crowd are clear of the patient and resume five cycles of CPR.

4. Continue CPR until Advanced Life Support becomes available


Recovery Position

Once the patient has regained consciousness, it is important to place them in the recovery position. This will help keep their airway open and prevent any further choking or aspiration of vomit. To place an adult in the recovery position:

1. Kneel beside the patient and roll them onto their side, with their uppermost leg bent at the knee and hip.

2. Place one arm behind their back and the other arm across their chest.

3. Tilt their head back slightly to open the airway.

4. Make sure they are stable and cannot roll onto their back or stomach.

5. Monitor the patient's breathing and pulse until medical help arrives.

6. If the patient stops breathing or their pulse weakens, begin CPR again.

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