For decades, pediatric resuscitation has taught us that when a child becomes bradycardic with poor perfusion and requires CPR, arrest-dose epinephrine is the natural next step. It’s a familiar reflex. It’s how we were trained.
But emerging data from the last several years has forced us to take a step back and ask an uncomfortable question:
Is early epinephrine always helping these children—or are there situations where its physiologic effects may contribute to further deterioration?
This article explores the evidence, the physiology, the disagreement between AHA and ILCOR, and the realities of why—despite concerning observational data—guidelines have not dramatically changed.
Most importantly, it examines what clinicians can do today with the evidence we currently have.
The Historical Logic Behind Early Epinephrine
The PALS algorithm was built on a foundational rule:
Pediatric bradycardia with poor perfusion is usually hypoxia-driven and pre-arrest. (6)
The thinking was:
- Bradycardia → worsening perfusion → impending arrest
- Therefore, correct it aggressively
- Epinephrine increases heart rate and contractility
- So: give it early, give it consistently
This was logical at the time. The evidence base was thin, but the algorithm had to be simple enough to teach and follow under stress.
But assumptions only hold until evidence challenges them.
Why Early Epinephrine Has Come Under Scrutiny
A child in bradycardia with a pulse is still perfusing. They are critically ill and often profoundly hypoxic, but they are not yet in complete cardiac arrest.
Their myocardium is struggling—but not yet failing. (8, 9)
When arrest-dose epinephrine is introduced into this fragile physiology, several physiologic effects occur:
- Afterload rises sharply
- Myocardial oxygen demand increases
- Catecholamine stress increases
- Electrical irritability may increase
In theory, these effects could potentially worsen myocardial oxygen imbalance in a heart already struggling to maintain effective perfusion.
Importantly, these concerns remain physiologically plausible hypotheses rather than proven mechanisms of direct harm.
This is what recent observational studies have attempted to explore.
What the Evidence Shows
Holmberg et al., 2020 (JAMA Cardiology)
Analyzed more than 7,000 pediatric resuscitations.
Children who received early epinephrine for bradycardia with poor perfusion:
- Had lower ROSC
- Had lower survival
- Had worse neurologic outcomes
- Were more likely to progress to pulselessness
This was association, not causation, but the pattern was striking. (1)
O’Halloran et al., 2024 (Critical Care)
Studied 452 children in bradycardia with poor perfusion requiring CPR.
Findings mirrored Holmberg:
- No improvement in ROSC
- No improvement in survival to discharge
- No neurologic benefit
- 46% progressed to pulselessness very early in resuscitation
When two independent, multi-center, peer-reviewed datasets show similar patterns across different populations and years, it becomes a signal that deserves careful scientific attention.
But Here’s the Crucial Point: Association ≠ Causation
This is where we must be precise.
Both studies were observational, not randomized.
This means:
- The sickest children often received epinephrine first.
- Their poor outcomes may reflect illness severity, not necessarily the medication itself.
- Clinicians—not researchers—decided who received epinephrine.
To definitively prove whether epinephrine itself contributes to harm, researchers would ideally need randomized controlled trials comparing treatment strategies directly.
However, designing an ethically acceptable randomized trial in critically ill children would be extraordinarily difficult, particularly when studying a medication historically considered potentially lifesaving.
This is why evidence in resuscitation science often remains imperfect and why guideline organizations must interpret data cautiously.
AHA vs ILCOR: Two Valid Interpretations of the Same Evidence
AHA PALS 2025
Still includes epinephrine once CPR begins for HR < 60 with poor perfusion.
This reflects a cautious and conservative approach:
- If evidence is uncertain, maintain established interventions that may still provide benefit.
- Do not prematurely remove potentially lifesaving therapies.
ILCOR 2025
Reviewed many of the same studies and concluded that current evidence was insufficient to support a recommendation either for or against routine epinephrine use in this setting.
Their rationale:
- Evidence is very low certainty
- Data do not clearly demonstrate benefit or harm
This is not a contradiction.
It is simply two organizations navigating the same uncertainty differently.
And the clinician stands between:
- The algorithm
- The evidence
- The patient
Why This Matters Clinically
Because pediatric physiology is delicate.
A small physiologic shift can mean the difference between recovery and collapse.
The pediatric heart is:
- Less compliant
- More dependent on calcium
- Highly sensitive to oxygen delivery
- Less tolerant of prolonged hypoxia
When epinephrine is introduced before oxygenation and ventilation are optimized, there is concern that aggressive catecholamine stimulation may worsen myocardial oxygen imbalance in an already hypoxic myocardium.
This is not an anti-epinephrine message.
It is a pro-physiology message.
A Smarter Approach: What Clinicians Can Do Today
Even with evidence limitations, clinicians can still practice thoughtfully by focusing on physiology first:
- Correct hypoxia aggressively
Hypoxia remains one of the primary drivers of pediatric bradycardia.
- Ensure effective ventilation
Airway position, seal, rate, and tidal volume matter enormously.
- Perform high-quality compressions when indicated
- Identify reversible causes
H’s and T’s remain essential.
- Consider the entire physiologic picture
Support oxygen delivery, perfusion, and ventilation before focusing solely on pharmacology.
- Recognize where evidence remains strongest
The strongest evidence supporting epinephrine remains in pulseless cardiac arrest, while its role in bradycardia with poor perfusion continues to be debated and studied.
This is not rebellion against guidelines.
It is responsible interpretation of evolving evidence.
So Why Not Change the Guidelines?
Because:
- The evidence is observational, not causal
- Ethical barriers limit higher-quality randomized trials
- Removing epinephrine prematurely could unintentionally harm patients
- Guidelines must remain cautious, stable, and defensible
The evidence is not strong enough to rewrite the algorithm outright.
But it is strong enough to encourage continued scientific discussion and physiologic reflection.
This is how medicine evolves:
not by ignoring evidence, and not by abandoning guidelines, but by integrating both with critical thinking.
The Final Message: Guidelines Guide — Clinicians Think
The controversy around epinephrine in pediatric bradycardia is not about choosing sides between AHA and ILCOR.
It is about understanding:
- The limitations of evidence
- The realities of research ethics
- The nuances of pediatric physiology
- The importance of thoughtful clinical judgment
We must follow our guidelines.
We must respect the evidence we have.
And we must think like clinicians, not technicians.
One day, better evidence may come.
Until then, the safest path is to honor both the algorithm and the physiology and to remember that the child in front of us deserves nothing less.
This discussion is not intended to replace established resuscitation guidelines or institutional protocols, but rather to encourage clinicians to critically examine evolving evidence and continue refining their understanding of pediatric resuscitation physiology.
References
- Holmberg MJ, Ross CE, Fitzmaurice GM, et al.
Association Between Early Epinephrine Administration and Outcomes in Pediatric In-Hospital Cardiac Arrest With Bradycardia and Poor Perfusion.
JAMA Cardiology. 2020;5(5):1–10. - O’Halloran AJ, Raymond TT, Guerguerian AM, et al.
Early Bolus Epinephrine Administration During Pediatric Cardiopulmonary Resuscitation for Bradycardia With Poor Perfusion.
Critical Care. 2024;28:1018. - International Liaison Committee on Resuscitation (ILCOR).
2025 Pediatric Life Support – Consensus on Science With Treatment Recommendations (CoSTR).
ILCOR; 2025. - American Heart Association (AHA).
Pediatric Advanced Life Support (PALS) Guidelines: 2025 Update.
AHA; 2025. - Sutton RM, Berg RA, Nadkarni VM.
Pediatric Cardiopulmonary Resuscitation: Advances in Physiology.
Circulation. 2020;142(7):608–610. - Topjian AA, Raymond TT, Atkins DL, et al.
Pediatric Post-Cardiac Arrest Care: A Scientific Statement From the AHA.
Circulation. 2019;140:e194–e233. - Atkins DL, Sasson C, Berg RA, et al.
Part 4: Pediatric Basic and Advanced Life Support.
Circulation. 2020;142(16_suppl_2):S469–S523. - Berg MD, Hansen M, Nadkarni VM, et al.
Pediatric Bradycardia and Arrest Physiology: Mechanisms and Clinical Principles.
Pediatric Critical Care Medicine. 2018;19(8):716–722. - Marino BS, Tabbutt S, Ghanayem NS, et al.
Physiology of the Pediatric Myocardium: Implications for Resuscitation.
Cardiology in the Young. 2019;29(11):1305–1314.