Beyond ACLS: A New Pulseless Electrical Activity Algorithm

Patients with pulseless electrical activity (PEA) account for almost 1/3 of cardiac arrest and even more troublesome is that the survival rate is significantly worse than patients with shockable rhythms. Both the European and American ACLS guidelines stress the importance of quickly finding and addressing the cause of PEA. This is traditionally done with recalling the 5 to 6 H’s and T’s, but during cardiopulmonary resuscitation it is difficult to recall all 13 causes of PEA by trying to recall this list. In 2014 a review article was published that was developed by several departments from the Carolinas Medical Center in Charlotte, NC that tried to simplify the diagnostic approach to PEA.

A New Simplified and Structured Method in the Evaluation and Management of Pulseless Electrical Activity

What are the traditionally taught H’s and T’s of PEA?

Traditional Causes of PEA

*Hypoglycemia and trauma have been removed from the most recent ACLS guidelines.

What is the new diagnostic classification of PEA?

  • Step 1: Determine if the PEA is narrow (QRS duration <0.12) or wide (QRS duration ≥0.12) simply by looking at the telemetry monitor
  • Step 2: Narrow-complex PEA is generally due to mechanical problems caused by right ventricular inflow or outflow obstruction
  • Step 3: Wide-complex PEA is typically due to metabolic problems, or ischemia and left ventricular failure

New Classification of PEA

Narrow-Complex PEA

Point of care ultrasound (POCUS) can quickly aid in identification of mechanical causes of PEA. A collapsed right ventricle suggests an inflow obstruction (i.e tamponade, pneumothorax, or hyperinflation) whereas a dilated right ventricle indicates outflow obstruction (i.e. Pulmonary emobolism).

Most Common Causes:

  • Cardiac Tamponade
  • Tension Pneumothorax
  • Mechanical Hyperinflation
  • Pulmonary Embolism


  • Aggressive intravenous fluid administration
  • Cardiac Tamponade –> Pericardiocentesis
  • Tension Pneumothorax –> Needle decompression
  • Mechanical Hyperinflation –> Adjust ventilator
  • Pulmonary Embolism –> Thrombolytic therapy

Narrow Complex PEA Management

Wide-Complex PEA

This typically suggests a metabolic or toxic ingestion problem. Hyperkalemia and/or sodium channel blocker toxicity.


  • Hyperkalemia –> Intravenous calcium chloride or gluconate
  • Hyperkalemia or Sodium Channel Blocker Toxicity –> Sodium bicarbonate

Wide Complex PEA Management


This new classification system of PEA has 3 potential benefits compared to the traditional ACLS 5 H’s and 5 T’s

  1. Rather than randomly listing 10 – 13 causes of PEA by memorizing the H’s and T’s, this new algorithm categorizes the possible causes of PEA based on the easy finding of QRS complexes being narrow or wide.
  2. Within each category there is a marked decrease in the etiologies one has to remember and is based on the etiologies with the highest likelihood and clinical relevance.
  3. This algorithm also provides specific treatment recommendations that are based on the initial QRS morphology.

What are the limitations of this classification system?

  • This algorithm does not apply to the trauma setting
  • This algorithm has not been systematically tested for inclusiveness or resuscitation outcomes
  • Narrow-complex PEA almost always indicates a mechanical cause, but occasionally mechanical causes can present with wide-complex PEA. (i.e. pre-existing bundle branch blocks, massive PE causing RBBB, and acute MI causing new LBBB)

Conclusion: Using the new classification system of PEA simplifies the working differential and initial treatment approach in conjunction with bedside ultrasound, however this strategy has not been tested systematically, tested for resuscitation outcomes, and caution should be used before implementing this algorithm until further studies are performed in the clinical setting.

For More on This Topic Checkout:


  1. Littmann et al. A Simplified And Structured Teaching Tool for the Evaluation and Management of Pulseless Electrical Activity. Med Princ Pract 2014; 23: 1 – 6. PMID: 23949188

Post Peer Reviewed by: Anand Swaminathan, MD (Twitter: @EMSwami)

Cite this article as: Salim Rezaie, "Beyond ACLS: A New Pulseless Electrical Activity Algorithm", REBEL EM blog, May 18, 2015. Available at:
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Salim Rezaie

Emergency Physician at Greater San Antonio Emergency Physicians (GSEP)
Creator & Founder of REBEL EM

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21 thoughts on “Beyond ACLS: A New Pulseless Electrical Activity Algorithm”

  1. This is an innovative approach that makes a lot of sense, rather than just trying to fit the case to a laundry list of possible diagnoses/therapies.

    Only comment I would make is that if PEA arrest believed to be due to hyperinflation/AutoPEEP then probably best to dc the ET tube/LMA for a bit and continue compressions rather than just adjust ventilation.

    Thanks for sharing this!

    • Hey Tim,
      TY for the comment and thoughts. I think this is a much more physiologic and logical way to think of PEA. I would mention that this has not been validated yet, so before we all get super excited about this, would be nice to see a validation study.
      For your comment about the hyperinflation/AutoPEEP, agreed in the acute setting, maybe best to not put back on the ventilator and just continue CPR. But when it is time to put the patient back on the ventilator, adjustment of the TV to a lower number would be ideal.
      TY for reading and glad you liked this.


  2. I think this approach to PEA is a step forward but I would suggest that the therapeutic value of external cardiac compression in many scenarios of PEA is unproven and is possibly negative. There is no evidence that ECC can increase cardiac output in any scenario where impaired cardiac filling is the limiting factor to cardiac output. If impaired filling is the limiting factor, ECC can only increase output if it increases filling. At least half of the cardiac compressions will occur in diastole and ECC will also raise mean intrathoracic pressure.These effects can be expected to reduce cardiac filling and therefore to reduce output.

    • Hello Tom,
      TY for reading and your comments… any OHCA….high quality, uninterrupted CPR is the key to survival with GOOD neurologic outcomes. This is something I emphasize during codes in the hospital/ED as well as my teaching to learners. Everything that I have listed above is secondary to high quality CPR. Excellent points and thank you for stating them here.


    • Interesting point Tom. Starting external chest compressions is a reflex during cardiac arrest, regardless of the etiology. I wonder if there could be a mortality benefit to NOT doing chest compressions in cases of impaired filling (tension pneumo, tamponade), as the heart is already producing sufficient inotropy, its just that there’s insufficient preload. This same idea is reflected by the fact that ECC in traumatic cardiac arrest is frowned upon, a situation in which tension pneumo and tamponade are often culprits. It would be interesting to see a study on this but very difficult to design and execute properly.

  3. Logical and easy way for PEA management
    But it should written in sequence in ALS algorithm
    When we should try to manage the specific
    cause of PEA during CPR

    • Hello Musaab,
      Great point you bring up…..when would you do all this?….in my mind:

      1. High Quality Uninterrupted CPR, IV-O2-Monitor (These all happen at the same time)
      2. At some point someone is going to do a pulse check (This is the best time to quickly look for RV dilatation or collapse)…should take no more than a few seconds.

      Hope this helps and great logistical question….would also love to hear others thoughts


  4. Curious how much PEA you see anymore. The vast majority of EMS systems are encouraging on-scene attempts at resuscitation and termination in field if no ROSC obtained (with some limited exceptions). I’ve found my numbers of PEA arrest in the ED have gone down significantly. This may not be a bad thing as the outcomes were extraordinarily poor to start with

    • Hey Brett,
      I guess it depends on what kind of system you work in. We still see quite a bit of PEA at my shop, and codes are not called pre-hospital. I agree the outcomes are not so hot when you look at the literature. If you are lucky enough to work in a system that calls it, great, but just in case you don’t….the above is a more physiologic way to think of PEA instead of the “Hs and Ts” we are all taught in ACLS.


  5. Pingback: PEA | resuscitera

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