BLS algorithms

These algorithms are based on the latest 2020 version from the American Heart Association. Our BLS course follows the 2020 American Heart Association guidelines for CPR and ECC.

Panel one

The first key concept of basic life support (BLS) is the order to perform actions. It is helpful to remember C - A - B.

Panel two

It is important to understand the rationale behind the actions taken. The following is a synopsis of key concepts of basic life support.

Crucial concepts Rationale
Start compressions within 10 seconds of identification of cardiac arrest. The brain and heart are both extremely sensitive to loss of oxygenation. Restoring blood flow to them as soon as possible is directly related to the possibility of survival..
Push hard, push fast. Adequate depth and rate of compressions assures that blood flow is adequate to oxygenate tissues
Allow complete chest recoil after each compression Chest recoil is the diastolic (resting) phase of circulation. This is when the brain and heart (as well as other vital organs) are supplied with blood. In addition, releasing the chest completely permits the heart to fill with blood prior to the next compression.
Minimize interruptions (less than 10 seconds) Each time compressions are paused, pressures in the body that are responsible for supplying blood to the brain and heart fall to zero. It takes many compressions to build back up to an acceptable pressure. (coronary perfusion pressure)
Give effective breaths to ensure chest rise Seeing the chest rise ensures that you have delivered enough air to the lungs to cause them to inflate adequately to supply oxygen for circulation.
Avoid excessive ventilation. Excessive ventilation causes the lungs to be filled with air continuously. This increases the pressure in the chest and prevents blood from flowing into the ventricles during the diastolic (relaxation) phase. Therefore, there is no blood available for circulation with compressions.

Panel three

Five simple steps to save a life

  1. Assess the patient for the presence or absence of normal breathing. Small intermittent breaths (agonal respirations) do not count as normal breathing. The healthcare provider can take 5–10 seconds to check for the presence of a carotid pulse.
  2. Call 911 outside the hospital, or activate the emergency response team within a facility. They should bring the defibrillator or automated external defibrillator (AED) with them.
  3. If breathing and pulse are absent, start compressions without delay. If the patient is not breathing but has a pulse, start rescue breathing.
  4. The AED or defibrillator should be placed on the patient as soon as it is available. Defibrillation should be completed as indicated by the cardiac rhythm or in the case of an AED, as directed by the AED.
  5. Prevent exhaustion by rotating compressors every two minutes or when getting fatigued. Give each other feedback about pace and depth of compressions.

Panel four

Rationale behind resuscitation steps

Step Notes  
1 Assess the patient Fast assessment is important to avoid delays in beginning resuscitation.
2 Activate the emergency response system. Both in and out of the hospital help is required to provide adequate resuscitation. In adult cardiac arrest 95% require defibrillation in the first few minutes following cardiac arrest. Early activation gets the AED or defibrillator to the patient sooner.
3 Pulse check Healthcare providers can check for the presence of a carotid pulse. It should take no longer than 5–10 seconds. If there is doubt as to whether a pulse is present, compression should be started.
4 Start CPR CPR should be started on all patients without a pulse or in the absence of normal breathing if the presence of a pulse cannot be determined.
5 Use the AED or defibrillator when it arrives Defibrillation is the definitive care for the most common arresting rhythm; ventricular fibrillation. If an AED is utilized, it should be changed to a manual defibrillator as soon as one arrives with personnel capable of nterpreting the rhythm.

Panel five

Pediatric basic life support

Although similar, there are key differences to the resuscitation of pediatric patients. (Patients who are pre-puberty or less than 8 years of age) The cause of arrest is very different from adults. Their arrest is almost always secondary to a cause other than cardiac such as respiratory failure or hypovolemia. For this reason, oxygenation is of paramount importance in pediatric resuscitation.

No. Step Notes
1 Assess the patient for breathing and presence or absence of a pulse simultaneously Assessing for breathing and pulse at the same time saves precious seconds and provides the information needed to make the decision to begin resuscitation.
2 Activate the emergency response team If alone and without a phone, CPR should be started for 2 minutes prior to leaving the patient to get help. This ensures that the patient is oxygenated adequately.
3 Start CPR with compressions Begin CPR if the patient has no pulse or if the pulse rate is less than 60 and the patient is unconscious. During pediatric resuscitation, bradycardia (heart rate less than 60) is a terminal event and should be treated with compressions and ventilations.
4 Compressions Compress the chest half of its depth (1.5 inches in infants and 2 inches in children) at a rate of 100–120 beats per minute. If two Healthcare providers are present, utilize a ratio of 15:2 rather than 30:2.
5 Ventilations If the child has a pulse, or has an advanced airway in place, perform at a rate of 20–30 a minute. The smaller the child, the higher the rate. This is one breath every 2–3 seconds.
6 AED Attach and utilize the defibrillator as soon as available.

The American Heart Association name is owned by American Heart Association, Inc. Pacific Medical Training has no affiliation with American Heart Association.

Written by

Judith has helped write or review several medical publications for us. Everything that she works on will clearly include Judith’s name.

Last reviewed and updated by on Sep 16, 2021

Caitlin Goodwin, DNP, RN, CNM, is a Board Certified Nurse-Midwife, Registered Nurse, and freelance writer. She has over twelve years of experience in nursing practice.