ACLS and CPR are not the same thing, though they’re closely related. CPR (cardiopulmonary resuscitation) is a specific technique of chest compressions and breaths used to keep blood flowing when someone’s heart stops. ACLS (Advanced Cardiovascular Life Support) is a broader set of protocols that includes CPR but adds medications, advanced airway tools, heart rhythm analysis, and post-arrest care. Think of CPR as one tool in the toolbox, and ACLS as the entire toolbox.
What CPR Actually Covers
CPR is the physical act of pushing on someone’s chest to manually pump blood through their body when the heart can no longer do it on its own. For laypeople, this typically means chest compressions only. Healthcare providers are trained to deliver both compressions and breaths, using a ratio of 30 compressions to 2 breaths. The 2025 American Heart Association guidelines dropped the term “rescue breaths” in favor of simply “breaths” to keep the language straightforward.
CPR falls under what’s called Basic Life Support, or BLS. BLS includes recognizing cardiac arrest, calling for help, performing CPR, and using an automated external defibrillator (AED) if one is available. An AED is the device you’ll see mounted on walls in airports and gyms. It reads the heart’s rhythm automatically and tells you whether to deliver a shock. No medical training is needed to use one.
BLS classes are open to everyone but are designed primarily for healthcare workers and first responders. Anyone can learn CPR, and the skills are intentionally kept simple so that bystanders will actually use them in an emergency.
What ACLS Adds Beyond CPR
ACLS picks up where basic CPR leaves off. It’s a structured set of protocols for managing cardiac arrest, dangerous heart rhythms, stroke, and other life-threatening cardiovascular emergencies. While CPR keeps blood moving mechanically, ACLS aims to restart the heart and stabilize the patient using a much wider range of interventions.
The major additions in ACLS include:
- Medications: Drugs that constrict blood vessels to improve blood flow to the heart and brain during arrest, and antiarrhythmic drugs to stabilize dangerous heart rhythms. These are given intravenously, typically every 3 to 5 minutes during active resuscitation.
- Advanced airway management: Instead of basic mouth-to-mouth or a bag-valve mask, ACLS providers can place a breathing tube directly into the windpipe or use a supraglottic airway device. Once one of these is in place, compressions and breaths happen continuously rather than in alternating cycles.
- Manual defibrillation: Unlike an AED, which analyzes the rhythm for you, a manual defibrillator requires the provider to read the heart’s electrical activity on a monitor and decide when and how much energy to deliver. Research on in-hospital cardiac arrests found that manual defibrillators produced shorter pauses in chest compressions by about 8 seconds compared to AEDs, which matters because every second without compressions reduces the chance of survival.
- Diagnosing reversible causes: ACLS providers systematically work through a checklist of 12 treatable conditions that may have caused the arrest, known as the “H’s and T’s.” These include low blood volume, low oxygen, blood clots in the lungs or heart, toxic exposures, and severe electrolyte imbalances. Identifying and treating the underlying cause is often what determines whether the patient survives.
Post-Arrest Care: Where ACLS Keeps Going
One of the biggest differences is what happens after the heart starts beating again. In basic CPR, your job is essentially done once a pulse returns or emergency medical services arrive. ACLS protocols extend well beyond that moment.
After a pulse returns, ACLS-trained teams manage oxygen levels carefully, keeping blood oxygen saturation between 90% and 98%. They maintain blood pressure above specific thresholds using medications, monitor carbon dioxide levels to protect the brain, and use imaging like CT scans or cardiac ultrasound to figure out what caused the arrest. Temperature control, maintained for at least 36 hours in patients who remain unconscious, is another cornerstone of post-arrest care. Some patients will need a procedure to open blocked coronary arteries. None of these steps exist in the CPR or BLS framework.
Who Needs Which Certification
BLS certification is the baseline for virtually anyone working in healthcare, from medical assistants to physicians. It’s also valuable for lifeguards, teachers, coaches, and anyone who wants to be prepared for a cardiac emergency.
ACLS certification is designed specifically for healthcare professionals who manage complex emergencies: physicians, nurses, paramedics, anesthesiologists, respiratory therapists, and dentists. The American Heart Association’s ACLS course builds directly on BLS skills, so you need a solid foundation in CPR before taking it. The course assumes you can already perform high-quality compressions and use an AED, then layers on rhythm interpretation, medication protocols, and team-based resuscitation.
Does More Advanced Care Mean Better Outcomes?
Surprisingly, not always. A large study published in JAMA Internal Medicine compared survival after out-of-hospital cardiac arrests treated by BLS-level responders versus those treated by advanced life support teams. After adjusting for differences between patients, survival to hospital discharge was 13.1% in the BLS group compared to 9.2% in the ALS group. Neurological outcomes were also better in the BLS group: among patients admitted to the hospital, 21.8% had poor neurological function after BLS care versus 44.8% after ALS care.
This doesn’t mean advanced care is harmful. The likely explanation is timing: patients who received only BLS tended to have arrests in locations where bystanders started CPR immediately, and early, high-quality chest compressions are the single most important factor in survival. Patients treated by advanced teams often had longer delays before CPR began or had more complex medical situations to begin with. The takeaway is that fast, effective chest compressions matter more than any medication or advanced airway, especially in the first few minutes.
ACLS becomes most valuable in the hospital setting or when basic interventions alone aren’t restoring a pulse. For prolonged arrests, for identifying and treating reversible causes, and for the critical hours after the heart restarts, advanced protocols make the difference between survival and death.