Introduction
Cardiac arrest is one of the leading causes of sudden death worldwide. Every minute without cardiopulmonary resuscitation (CPR) and defibrillation significantly reduces the chance of survival. Immediate recognition of cardiac arrest, early activation of emergency medical services (EMS), prompt initiation of high-quality CPR, and rapid use of an Automated External Defibrillator (AED) are the cornerstones of successful resuscitation.
Whether you are a healthcare professional, medical student, nurse, dentist, respiratory therapist, EMT, athletic trainer, or concerned member of the public, understanding the fundamentals of CPR can make the difference between life and death.
This comprehensive guide explains adult CPR step by step, reviews current Basic Life Support (BLS) principles, discusses proper AED use, highlights common mistakes, and answers frequently asked questions. While this article provides educational information, formal hands-on CPR and BLS training remains strongly recommended for anyone expected to respond to medical emergencies.
What Is CPR?
Cardiopulmonary Resuscitation (CPR) is an emergency life-saving technique used when a person’s heart has stopped beating effectively or they have stopped breathing normally because of cardiac arrest.
The primary goals of CPR are to:
- Maintain blood flow to the brain
- Deliver oxygen to vital organs
- Delay irreversible organ damage
- Increase the likelihood of successful defibrillation
- Improve survival until advanced medical care arrives
CPR is only one component of the Chain of Survival, which also includes rapid emergency activation, early defibrillation, advanced life support, and high-quality post-cardiac arrest care.
What Is Cardiac Arrest?
Cardiac arrest occurs when the heart suddenly stops pumping blood effectively.
Without circulation:
- the brain begins to suffer irreversible injury within minutes,
- oxygen delivery stops,
- vital organs fail,
- death rapidly follows unless circulation is restored.
Cardiac arrest is not the same as a heart attack.
A heart attack occurs when blood flow to part of the heart muscle is blocked. Although a heart attack can sometimes lead to cardiac arrest, many patients experiencing a heart attack remain awake and conscious.
Cardiac arrest, in contrast, results in sudden collapse, unresponsiveness, and absence of normal breathing.
Recognizing this distinction is critical because cardiac arrest requires immediate CPR and often rapid defibrillation.
When Should CPR Be Started?
CPR should begin immediately whenever an individual:
- suddenly collapses,
- is unresponsive,
- is not breathing normally,
- or is only gasping.
Occasional gasping, also called agonal breathing, should not be mistaken for normal breathing. Agonal respirations frequently occur during cardiac arrest and should prompt immediate initiation of CPR.
If you are uncertain whether the patient is truly in cardiac arrest, it is generally safer to begin CPR while emergency responders are on the way.
Why Every Minute Matters
The chances of surviving cardiac arrest decrease rapidly with every minute that passes without CPR.
Early chest compressions help maintain a limited amount of blood flow to the brain and heart until definitive treatment becomes available.
Similarly, early defibrillation dramatically improves outcomes in patients with shockable rhythms such as ventricular fibrillation (VF) and pulseless ventricular tachycardia (VT).
This is why CPR and AED use are emphasized together in modern Basic Life Support programs.
The Adult Chain of Survival
Successful resuscitation depends on several coordinated steps occurring as quickly as possible.
These include:
- Early recognition of cardiac arrest.
- Immediate activation of emergency medical services.
- High-quality CPR.
- Rapid defibrillation using an AED when indicated.
- Advanced Cardiovascular Life Support (ACLS).
- Comprehensive post-cardiac arrest care and rehabilitation.
Weakness in any one step may reduce the patient’s likelihood of survival.
Adult CPR: Step-by-Step Instructions
Step 1: Ensure Scene Safety
Before approaching the patient, quickly assess your surroundings.
Confirm that the environment is safe for both the victim and rescuer.
Potential hazards include:
- electrical wires
- traffic
- fire
- chemicals
- unstable structures
- violent situations
Never place yourself in danger while attempting a rescue.
Step 2: Check Responsiveness
Approach the individual.
Tap their shoulders firmly.
Ask loudly:
“Are you okay?”
If there is no response, immediately proceed with further assessment.
Step 3: Activate Emergency Medical Services
Call your local emergency number immediately or direct another person to do so.
If other rescuers are present:
- assign someone to call EMS,
- ask another person to retrieve the nearest AED,
- begin CPR immediately.
Early activation ensures professional responders are dispatched without delay.
Step 4: Check Breathing
Look for:
- normal chest movement,
- effective breathing,
- purposeful respirations.
Do not spend more than about 10 seconds checking.
If the patient:
- is not breathing,
- is only gasping,
- or has abnormal breathing,
begin CPR immediately.
Step 5: Begin High-Quality Chest Compressions
Chest compressions are the most important component of CPR.
Proper compressions temporarily circulate oxygenated blood throughout the body until spontaneous circulation returns or advanced interventions become available.
Hand Placement
Place the heel of one hand on the center of the chest over the lower half of the sternum.
Place your second hand directly on top.
Interlock your fingers.
Keep your elbows locked.
Position your shoulders directly over your hands.
Use your upper body weight—not only your arms—to compress the chest.
Compression Rate
Perform compressions at a rate of:
100–120 compressions per minute.
A slower rate provides inadequate circulation.
An excessively rapid rate often leads to shallow compressions and rescuer fatigue.
Compression Depth
Compress the chest approximately:
2 inches (5 cm)
Avoid compressions deeper than approximately 2.4 inches (6 cm), which may increase the risk of injury while providing little additional benefit.
Allow Complete Chest Recoil
After every compression:
allow the chest to return completely to its normal position.
Incomplete recoil reduces venous return to the heart and decreases cardiac output generated during CPR.
Avoid leaning on the chest between compressions.
Minimize Interruptions
Interruptions should be as brief as possible.
Whenever compressions stop:
blood flow immediately decreases.
Restart compressions without delay after rhythm checks, AED analysis, or rescue breaths.
Rescue Breathing During Adult CPR
While chest compressions are the foundation of CPR, rescue breaths provide oxygen to the lungs and bloodstream. The appropriate use of rescue breathing depends on the rescuer’s level of training and whether an advanced airway is present.
How to Give Rescue Breaths
After completing 30 chest compressions:
- Open the airway using the head tilt–chin lift maneuver.
- If cervical spine injury is strongly suspected, trained providers may use a jaw thrust while minimizing neck movement.
- Pinch the victim’s nose closed.
- Create a tight seal over the patient’s mouth using your mouth or a barrier device.
- Deliver one breath over approximately 1 second, watching for visible chest rise.
- Deliver a second breath in the same manner.
- Resume chest compressions immediately.
Each rescue breath should produce gentle chest rise. Excessive ventilation can increase intrathoracic pressure, reduce blood return to the heart, and decrease the effectiveness of CPR.
Compression-to-Ventilation Ratio
For adult CPR without an advanced airway, the recommended ratio is:
30 chest compressions : 2 rescue breaths
This ratio is used by both single rescuers and two-rescuer teams in adult Basic Life Support.
Once an advanced airway (such as an endotracheal tube or supraglottic airway) has been placed by trained providers:
- Chest compressions should continue continuously without interruption.
- Rescue breaths are delivered independently at approximately 1 breath every 6 seconds (10 breaths per minute).
Hands-Only CPR
Hands-only CPR has transformed bystander response to cardiac arrest by simplifying the technique and encouraging more people to intervene.
If you are not trained in CPR or are uncomfortable providing rescue breaths:
- Call emergency medical services immediately.
- Begin chest compressions.
- Push hard and push fast in the center of the chest.
- Continue until an AED is available or emergency responders take over.
For sudden adult cardiac arrest occurring outside the hospital, hands-only CPR has been shown to improve survival compared with no CPR at all.
Why High-Quality Chest Compressions Matter
Every chest compression temporarily pumps a small amount of blood to the brain and heart. Although CPR cannot fully replace normal heart function, it can preserve critical organ perfusion until definitive treatment is available.
High-quality CPR is characterized by:
- Compression rate of 100–120 per minute
- Compression depth of approximately 2 inches (5 cm)
- Full chest recoil after every compression
- Minimal interruptions
- Avoidance of excessive ventilation
These principles form the foundation of modern Basic Life Support (BLS) and Advanced Cardiovascular Life Support (ACLS).
How to Use an Automated External Defibrillator (AED)
An Automated External Defibrillator (AED) is designed to analyze heart rhythm and deliver an electrical shock when indicated.
AEDs are found in many public locations, including:
- Airports
- Schools
- Shopping centers
- Sports facilities
- Government buildings
- Offices
- Community centers
- Hospitals
Modern AEDs provide clear voice prompts that guide rescuers through each step.
Step-by-Step AED Use
Step 1: Turn On the AED
Open the AED case and power on the device.
Most AEDs begin providing spoken instructions immediately.
Follow each prompt carefully.
Step 2: Expose the Chest
Remove clothing covering the chest.
Dry the chest if it is wet.
If excessive chest hair prevents pad adhesion, quickly shave the pad placement areas if a razor is available with the AED.
Medication patches should be removed before placing pads directly over the area.
Step 3: Apply the AED Pads
Place one adhesive pad:
- Below the right collarbone.
Place the second pad:
- On the left side of the chest below the armpit.
Follow the diagrams printed on the pads.
Correct pad placement allows the electrical current to pass effectively through the heart.
Step 4: Allow Rhythm Analysis
Once the pads are attached:
The AED will analyze the patient’s heart rhythm.
During analysis:
No one should touch the patient.
Movement can interfere with rhythm interpretation.
Step 5: Deliver a Shock if Advised
If the AED recommends a shock:
- Ensure everyone is clear of the patient.
- Loudly announce:
“Clear!”
- Visually confirm that no one is touching the patient.
- Press the shock button if required.
Some AEDs deliver the shock automatically.
Step 6: Resume CPR Immediately
Immediately after shock delivery:
Resume chest compressions without checking for a pulse.
Continue CPR for approximately two minutes before the AED performs another rhythm analysis.
This minimizes interruptions in circulation.
Which Rhythms Can an AED Treat?
An AED is designed to recognize shockable cardiac rhythms.
These include:
- Ventricular Fibrillation (VF)
- Pulseless Ventricular Tachycardia (VT)
The AED will not recommend a shock for non-shockable rhythms such as:
- Asystole
- Pulseless Electrical Activity (PEA)
Understanding these rhythms is an important component of Advanced Cardiovascular Life Support (ACLS).
CPR and AED: Why They Work Together
CPR and defibrillation are complementary interventions.
CPR temporarily maintains circulation.
Defibrillation attempts to restore an organized electrical rhythm capable of producing an effective heartbeat.
Without CPR, the heart and brain rapidly become deprived of oxygen.
Without defibrillation, many patients with ventricular fibrillation cannot regain spontaneous circulation.
For this reason, CPR should continue until an AED is available and immediately resume after each rhythm analysis or shock.
Common CPR Mistakes
Even experienced rescuers can make errors that reduce CPR effectiveness.
Some of the most common mistakes include:
Performing Compressions Too Slowly
Slow compressions generate inadequate blood flow.
Maintain a steady rate of 100–120 compressions per minute.
Shallow Chest Compressions
Compressions that are too shallow fail to generate sufficient circulation.
Aim for a depth of approximately 2 inches (5 cm) in adults.
Leaning Between Compressions
Failing to allow complete chest recoil decreases blood return to the heart.
Lift pressure completely after every compression.
Excessive Interruptions
Stopping compressions unnecessarily reduces coronary and cerebral perfusion.
Interrupt CPR only when absolutely necessary, such as during rhythm analysis or shock delivery.
Overventilation
Providing breaths too rapidly or forcefully may increase intrathoracic pressure and decrease cardiac output.
Deliver only enough air to produce visible chest rise.
Delayed AED Use
High-quality CPR is essential, but early defibrillation remains the definitive treatment for many shockable cardiac arrests.
Retrieve and apply the AED as soon as it becomes available.
Special Situations During CPR
Although the core principles of CPR remain consistent, certain emergency situations require additional considerations.
CPR in Pregnancy
Cardiac arrest during pregnancy is rare but represents a medical emergency for both the mother and fetus.
Key considerations include:
- Begin high-quality CPR immediately.
- Position the patient supine and manually displace the uterus to the left (performed by trained healthcare providers) to reduce compression of the inferior vena cava.
- Apply an AED if indicated—defibrillation is safe during pregnancy.
- Rapid transport to a facility capable of advanced maternal and neonatal care is essential.
Drowning Victims
Unlike many adult cardiac arrests, drowning typically results from oxygen deprivation before cardiac arrest occurs.
For trained rescuers:
- Begin CPR immediately.
- Rescue breaths are particularly important because hypoxia is the primary cause.
- Activate EMS as soon as possible.
Opioid Overdose
An opioid overdose may present with:
- Slow or absent breathing
- Pinpoint pupils
- Unresponsiveness
If opioid overdose is suspected:
- Call emergency services.
- Administer naloxone if available.
- Begin CPR if the patient is pulseless and not breathing normally.
- Continue resuscitation until advanced medical personnel arrive.
Trauma
Traumatic cardiac arrest often has causes different from sudden cardiac arrest, including:
- Severe blood loss
- Tension pneumothorax
- Cardiac tamponade
- Massive pulmonary embolism
While CPR should be initiated, definitive treatment requires rapid identification and correction of the underlying cause by emergency medical professionals.
CPR in Healthcare Settings
Healthcare professionals are expected to recognize cardiac arrest rapidly and initiate evidence-based Basic Life Support while preparing for Advanced Cardiovascular Life Support (ACLS).
Typical responders include:
- Physicians
- Nurses
- Paramedics
- Emergency Medical Technicians (EMTs)
- Respiratory Therapists
- Dentists
- Physician Assistants
- Medical Students
- Nursing Students
- Hospital Code Blue Teams
Healthcare providers should maintain current CPR, BLS, and ACLS knowledge through regular education and skills assessment.
CPR, BLS, and ACLS: What’s the Difference?
Although often used interchangeably, CPR, BLS, and ACLS are distinct concepts.
CPR (Cardiopulmonary Resuscitation)
CPR refers specifically to chest compressions and rescue breathing performed during cardiac arrest to maintain circulation until advanced care becomes available.
BLS (Basic Life Support)
Basic Life Support includes CPR but also encompasses:
- Recognition of cardiac arrest
- Activation of emergency medical services
- Proper AED use
- Airway management
- Team-based resuscitation principles
- Adult, child, and infant resuscitation techniques
BLS certification is commonly required for healthcare professionals and many allied health occupations.
ACLS (Advanced Cardiovascular Life Support)
ACLS builds upon BLS by incorporating advanced interventions such as:
- Cardiac rhythm interpretation
- Defibrillation
- Synchronized cardioversion
- Airway management
- Intravenous and intraosseous access
- ACLS medications
- Post-cardiac arrest care
- Management of bradycardia and tachycardia
Who Should Learn CPR?
Everyone can benefit from learning CPR.
Healthcare professionals who commonly require CPR and BLS certification include:
- Physicians
- Nurses
- Medical Students
- Dental Professionals
- EMTs
- Paramedics
- Respiratory Therapists
- Physical Therapists
- Occupational Therapists
- Physician Assistants
- Nurse Practitioners
- Athletic Trainers
- Emergency Department Personnel
- Intensive Care Unit Staff
However, CPR is equally valuable for parents, teachers, coaches, caregivers, workplace employees, and members of the general public. Early bystander CPR has been shown to improve survival following out-of-hospital cardiac arrest.
Frequently Asked Questions (FAQ)
What is the correct compression rate during adult CPR?
The recommended chest compression rate for adults is 100–120 compressions per minute, delivered with adequate depth and full chest recoil.
How deep should chest compressions be?
Adult chest compressions should be approximately 2 inches (5 cm) deep while avoiding excessive depth.
Should I perform rescue breaths?
Trained rescuers should provide rescue breaths using a 30:2 compression-to-ventilation ratio. If you are untrained or unwilling to provide rescue breaths, hands-only CPR is recommended until emergency medical services arrive.
Can an AED be used by someone without medical training?
Yes. Automated External Defibrillators are specifically designed for public use and provide clear voice prompts that guide rescuers through each step of the process.
What should I do if I am unsure whether the person is in cardiac arrest?
If an individual is unresponsive and not breathing normally or is only gasping, begin CPR immediately and activate emergency medical services. Delaying treatment may significantly reduce the chance of survival.
Does CPR restart the heart?
CPR does not usually restart the heart. Instead, it maintains limited blood flow to vital organs until defibrillation, advanced medical treatment, or spontaneous circulation restores effective cardiac function.
Is CPR enough without an AED?
High-quality CPR is essential, but early defibrillation substantially improves survival in patients with shockable rhythms such as ventricular fibrillation and pulseless ventricular tachycardia. CPR and AED use should be viewed as complementary interventions.
Key Takeaways
- CPR is a life-saving intervention that should begin immediately when an adult is unresponsive and not breathing normally.
- High-quality chest compressions remain the most important component of CPR.
- The recommended compression rate is 100–120 compressions per minute with a depth of approximately 2 inches (5 cm).
- Early use of an AED significantly improves survival in shockable cardiac arrest rhythms.
- Healthcare professionals should maintain current BLS and ACLS knowledge through regular training and continuing education.
- Prompt recognition, early CPR, rapid defibrillation, and advanced medical care together form the foundation of successful resuscitation.
Continue Your Emergency Cardiovascular Education
Learning CPR is only the first step in emergency cardiovascular care. Healthcare professionals who regularly respond to medical emergencies should also maintain competency in Basic Life Support (BLS) and Advanced Cardiovascular Life Support (ACLS).
Explore our educational resources to deepen your understanding of:
- BLS principles
- ACLS algorithms
- Bradycardia management
- Tachycardia management
- Pulseless Electrical Activity (PEA)
- Ventricular Fibrillation (VF)
- Asystole
- Return of Spontaneous Circulation (ROSC)
- Reversible causes of cardiac arrest (H’s and T’s)
- Automated External Defibrillator (AED) use
Whether you are preparing for certification, recertification, or simply expanding your emergency cardiovascular knowledge, continuing education and regular skills practice remain essential for delivering high-quality patient care.