Every second counts in a cardiac emergency. The American Heart Association (AHA) BLS algorithm gives healthcare providers a clear, step-by-step framework to act fast, minimize errors, and save lives. Whether you work in a hospital, clinic, or emergency setting, knowing this algorithm is non-negotiable.
The 2025 AHA Guidelines update — published in Circulation — refines how providers deliver high-quality CPR, use AEDs, and respond to emergencies like opioid-associated cardiac arrest. This article breaks down the 7 components of the BLS algorithm in order and explains what the latest guidelines require.
Why the BLS Algorithm Matters
Cardiac arrest kills over 350,000 Americans each year outside of hospital settings. According to the 2025 AHA Guidelines, survival to hospital discharge after EMS-treated adult out-of-hospital cardiac arrest (OHCA) was only 10.5% — with favorable neurological survival at 8.2%. Those numbers shift dramatically when bystanders act. Bystander-witnessed arrests where CPR was started immediately showed a 13.0% survival rate compared to 7.6% for unwitnessed arrests. Yet only 41.7% of OHCA patients received bystander CPR.
The BLS algorithm exists to change that. It removes guesswork, reduces hesitation, and gives every trained responder a reliable roadmap from scene assessment to defibrillation.
What Are the 7 Components of the BLS Algorithm in Order?
The AHA structures the BLS algorithm into seven sequential components. Each step builds on the last. Skipping or reversing the order reduces effectiveness.
- Scene Safety
Before touching a patient, scan the environment. Look for traffic, fire, electrical hazards, or unstable structures. A rescuer who becomes a second victim helps no one. This step is brief but critical — if the scene is unsafe, do not enter until it is controlled.
- Check for Responsiveness
Tap the patient’s shoulder firmly and shout: “Are you okay?” Look for any reaction — movement, eye opening, sounds. If the person does not respond, move immediately to the next step. Do not waste time waiting for a response that will not come.
- Activate the Emergency Response System
Call 911 (or direct someone else to call) and send for an AED. In a clinical setting, this means activating the facility’s emergency response. Early activation brings advanced life support faster. The 2025 guidelines reinforce that this step must happen simultaneously with — not after — initial assessment.
- Check for Breathing and Pulse
Check breathing and pulse at the same time. Look for no breathing or only gasping — agonal breathing is not normal breathing. Check the carotid pulse for no more than 10 seconds. If there is no pulse and no normal breathing, begin CPR immediately. Hesitation at this stage wastes precious time.
- High-Quality Chest Compressions
Start compressions immediately. The 2025 AHA guidelines reinforce the CAB sequence — Compressions, Airway, Breathing. Push hard and fast. For adults, compress at least 2 inches deep but no more than 2.4 inches. Maintain a rate of 100 to 120 compressions per minute. A National Institutes of Health registry analysis found the optimal combination was 107 compressions per minute at a depth of 4.7 cm — significantly improving neurologically favorable survival. Allow full chest recoil between compressions and minimize interruptions.
- Rescue Breaths
For a single rescuer performing adult BLS, use a 30:2 compression-to-ventilation ratio. Open the airway with a head-tilt chin-lift, deliver two rescue breaths, and watch for visible chest rise. Each breath should last about one second. For two rescuers managing pediatric patients, the ratio shifts to 15:2. Avoid over-ventilation — excessive breaths increase intrathoracic pressure and reduce cardiac output.
- AED Use and Defibrillation
Apply an AED as soon as one is available. Turn it on, attach the pads, and follow the audio prompts. If the AED advises a shock, deliver it. Resume CPR immediately after the shock. Early defibrillation dramatically increases survival rates in cases of shockable rhythms like ventricular fibrillation. The 2025 guidelines stress that pauses before and after shock delivery reduce blood flow and lower survival odds — so minimize them.
What Are the AHA Guidelines for BLS?
The 2025 AHA Guidelines represent the most current evidence-based standards for BLS practice. Here are the key specifications every provider needs to know:
- Compression rate: 100 to 120 compressions per minute for adults, children, and infants.
- Compression depth: At least 2 inches (5 cm) for adults; approximately 2 inches for children; approximately 1.5 inches for infants.
- Compression-to-ventilation ratio: 30:2 for a single rescuer; 15:2 for two rescuers in pediatric cases.
- Full chest recoil: Allow the chest to fully rise between compressions. Do not lean on the chest.
- Minimize interruptions: Keep CPR pauses to under 10 seconds. Prolonged pauses reduce blood flow to the brain and heart.
- CAB sequence confirmed: The 2025 update reinforces Compressions-Airway-Breathing. Start compressions first.
- Naloxone in BLS: The 2025 guidelines now explicitly include naloxone in the BLS algorithm for suspected opioid-associated cardiac arrest.
- Updated choking protocol: For adults and children, deliver 5 back blows followed by 5 abdominal thrusts until the obstruction clears or the patient loses consciousness.
- Unified Chain of Survival: A single, unified Chain of Survival now covers adults and pediatric patients in both out-of-hospital and in-hospital settings.
These guidelines apply to healthcare providers in all settings. The AHA reviews and updates them regularly, drawing on systematic reviews, meta-analyses, and registry data from organizations including the Resuscitation Outcomes Consortium and CARES (Cardiac Arrest Registry to Enhance Survival).
Who Needs BLS Certification?
BLS certification is required for a wide range of healthcare professionals. Nurses, physicians, paramedics, EMTs, dental hygienists, medical assistants, and physical therapists all need a current BLS card. Many employers and licensing boards mandate it as a condition of employment or renewal.
BLS for Healthcare Providers covers adult, child, and infant CPR, AED use, relief of foreign-body airway obstruction, and team-based resuscitation dynamics. It differs from standard CPR/First Aid, which targets the general public. BLS prepares providers for clinical environments where precise technique and coordinated team response are expected.
Certification is valid for two years. When you renew, your course must reflect the current AHA guidelines — confirm this before you register.
Get CPR Certification in Memphis or BLS Certification in Memphis Today
CPR Memphis is an American Heart Association training site offering initial certifications and renewals in BLS for Healthcare Providers, ACLS, PALS, and CPR and First Aid. All classes are stress-free and hands-on.
Whether you need CPR certification in Memphis for the first time or BLS certification in Memphis, CPR Memphis delivers AHA-aligned training in a supportive, skills-based environment. Small class sizes mean instructors can give you individual feedback on your compression technique, rescue breathing, and AED operation.
Don’t let your certification lapse — and don’t settle for a course that’s behind the 2025 guidelines. Register with CPR Memphis today and leave confident that your skills meet the latest AHA standards.
