Advanced Cardiovascular Life Support (ACLS) is a critical component of emergency cardiovascular care, and managing Pulseless Electrical Activity (PEA) and Asystole is a central part of the ACLS algorithm. These are two of the most serious cardiac arrest rhythms and require immediate intervention.
In this comprehensive guide, we’ll break down the recognition, causes, and treatment protocols for PEA and Asystole according to the latest ACLS guidelines.
What is Pulseless Electrical Activity (PEA)?
Pulseless Electrical Activity (PEA) happens when the heart’s electrical system seems to be working, but the heart muscle isn’t responding. You might see a rhythm on the monitor, but there’s no pulse, no blood flow, and the patient is not responsive.
How to Recognize PEA?
- The person is unresponsive and not breathing normally.
- There’s no pulse, even though a rhythm shows on the monitor.
- The rhythm can look slow or fast, regular or irregular — it doesn’t matter. If there’s no pulse, it’s considered PEA.
PEA is not a shockable rhythm. That means using a defibrillator won’t help. The treatment is focused on performing CPR, giving medications, and finding out what caused the heart to stop.
What is Asystole?
Asystole is often called a “flatline.” This is the point where the heart has no electrical activity at all. There’s no rhythm, no pulse, and no blood being pumped. It’s one of the most difficult rhythms to recover from, but immediate action can still make a difference.
How to Recognize Asystole?
- The ECG (heart monitor) shows a flat line.
- The person is not breathing and has no pulse.
- The monitor may show slight movement, but if there’s no organized activity and no pulse, it’s Asystole.
Asystole, like PEA, does not respond to shocks. This makes early CPR and finding the underlying cause all the more important.
What To Do: First Steps in a PEA or Asystole Situation
If someone is found unresponsive and not breathing normally:
- Start CPR right away – Push hard and fast in the center of the chest.
- Call for help and get emergency equipment – Use a bag-mask to give breaths.
- Attach a monitor or defibrillator – Check for rhythm. If it’s not shockable (PEA or Asystole), continue CPR
- Give Epinephrine – 1 milligram by IV or IO (into bone) every 3–5 minutes.
- Keep going with CPR – Pause every 2 minutes to check the rhythm and pulse.
- Look for what caused the arrest – Certain problems can be reversed if treated quickly.
Finding the Cause: The Hs and Ts
In many cases, PEA or Asystole happen because of something else going wrong in the body. If you can fix the cause, the heart may start working again. The most common causes fall into two groups — often called “Hs and Ts.”
Hs:
- Low blood volume (Hypovolemia) – Can happen from bleeding or dehydration.
- Low oxygen (Hypoxia) – The heart and brain need oxygen to work.
- Too much acid in the body (Acidosis) – Common in long arrests or illness.
- Potassium imbalance (Hyperkalemia or Hypokalemia) – Affects heart rhythm.
- Low body temperature (Hypothermia) – Especially in cold environments.
Ts:
- Air trapped in the chest (Tension pneumothorax) – Can compress the heart.
- Fluid around the heart (Cardiac tamponade) – Stops the heart from pumping.
- Poison or overdose (Toxins) – Some drugs can stop the heart.
- Blood clot in the lungs (Pulmonary embolism) – Blocks oxygen flow.
- Heart attack (Thrombosis of coronary artery) – Cuts off blood to the heart.
If you can find and fix one of these causes, the person’s chances of survival go up.
Treatment Overview for PEA and Asystole
| Step | What To Do |
| CPR | Start immediately. Push hard and fast, 100–120 times per minute. |
| Breathing | Give 1 breath every 6 seconds once airway is secured. |
| Medication | Give Epinephrine 1 mg every 3–5 minutes. |
| Rhythm Check | Every 2 minutes, pause CPR briefly to check. |
| Cause | Identify and treat the underlying issue (from the Hs/Ts list). |
| Shocks | Do not shock PEA or Asystole. Only shock certain other rhythms. |
How Long Should You Continue?
There’s no exact time limit, but here are a few points to consider:
- If there’s no improvement after 20–30 minutes, and no reversible cause is found, it may be time to stop.
- Decisions should be based on the situation, how quickly care was started, and the overall condition of the person.
Always involve a senior clinician or medical team leader in this decision.
Key Differences Between PEA and Asystole
| Feature | PEA | Asystole |
| ECG | Shows a rhythm | Flat line |
| Pulse | None | None |
| Shockable | No | No |
| Main focus | CPR + find cause | CPR + find cause |
Final Thoughts
Both PEA and Asystole are severe emergencies that require fast thinking and calm teamwork. While these rhythms are harder to treat than shockable ones, survival is still possible — especially if the right cause is found and corrected in time.
Remember:
- Start CPR immediately
- Give Epinephrine as early as possible
- Search for causes and fix what you can
- Don’t give up too early, but know when to stop
Staying calm, knowing the steps, and acting quickly can give someone the best chance to survive a sudden cardiac arrest.
