Today, I review, link to, and excerpt from Emergency Medicine Cases’ “Ep 215 Cardiac Arrest Update: Beyond the 2025 Guidelines Part 1: CPR, Defibrillation and Ventilation”.*
*Helman, A. Simard, R. Cheskes, S. Cardiac Arrest Update: Beyond the 2025 Guidelines Part 1: CPR, Defibrillation and Ventilation. Emergency Medicine Cases. March, 2026. https://emergencymedicinecases.com/cardiac-arrest-update-cpr-defibrillation-ventilation. Accessed April 23, 2026
All that follows is from the above resource.
Cardiac arrest care has always been about the fundamentals—high-quality CPR, timely defibrillation, and effective ventilation. But as our guest experts Dr. Sheldon Cheskes and Dr. Rob Simard make clear in this EM Cases update as we reflect on the latest 2025 AHA guidelines, the fundamentals are evolving in ways that challenge some of our most ingrained habits and assumptions. In Part 1 of this series, we take a deep dive into the practical bedside application of CPR, defibrillation, and ventilation—moving beyond “cookbook” algorithms toward a more nuanced, performance-driven approach. From rethinking pad placement and shock strategy, to interpreting ETCO₂ in context rather than chasing arbitrary numbers, to recognizing that even subtle leaning on the chest during compressions can undermine outcomes—this episode is packed with pearls that demand we recalibrate how we run resuscitations. We explore why measuring CPR quality—and feeding that information back in real time—is no longer optional but central to care. We unpack concepts like compression-adjusted ventilation, the role of arterial lines during arrest, and feedback devices. And perhaps most provocatively, we challenge traditional dogma and the questions: Is the two-minute cycle too rigid? Should we be shocking earlier? Is head up CPR a viable technique? and much more…
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Why this update on cardiac arrest management matters
The 2025 AHA ACLS Guidelines reaffirm what saves lives in cardiac arrest: rapid recognition, high-quality CPR, early defibrillation for shockable rhythms, timely vasopressor use, and coordinated post–cardiac arrest care. Those pillars are not new—and that’s the point. Survival gains in many systems have come less from novel drugs and more from better execution: faster emergency activation, higher bystander CPR rates, earlier AED deployment, and tighter choreography during resuscitation. What the guidelines cannot fully capture is the nuance required when the algorithm becomes sparse. In the ED, the most consequential decisions often occur precisely where evidence is uncertain and the flowchart stops giving direction—especially in VF after multiple shocks, epinephrine, and amiodarone with no ROSC. At that inflection point, the clinician has to think physiologically: Are we generating coronary perfusion pressure? Are we preserving it with compression fraction? Are we undermining ourselves with hyperventilation? Is VF truly shock-refractory or simply recurrent? Is our defibrillation technique actually delivering current through myocardium—or just delivering electricity into a high-impedance chest?
This episode focuses on those bedside inflection points—the places where small adjustments in timing, technique, and interpretation can plausibly change outcomes.
Quick list of what’s new since our last episode on cardiac arrest
Chain of Survival
- The chain of survival now explicitly adds recovery and survivorship as a 6th link, emphasizing ongoing support after hospital discharge rather than ending care at ROSC or discharge.
- Upstream system-level emphasis on dispatcher-assisted CPR, video-assisted CPR, crowdsourced responder/AED apps such as PulsePoint/FirstAED, and drone AED delivery to shorten time to first shock.
- A stronger endorsement of stay-and-play over load-and-go for most out-of-hospital arrests, based on the idea that paramedics can do nearly everything on scene that the ED can do, and that arrival to the ED without ROSC carries a very poor prognosis.
- A systems concept of transporting postarrest patients to cardiac arrest centers / organized centers of excellence with regular exposure to arrest care, PCI capability, targeted temperature management, and specialized ICU/cardiology/neurology support.
CPR
- A stronger practical message that measuring CPR quality and feeding it back to teams is itself central; when CPR quality was first objectively measured, essentially no system was delivering truly high-quality CPR.
- Discussion of noninvasive flow assessment during arrest, including a carotid flow patch concept, with the caution that some devices measure velocity rather than flow, and those are not equivalent.
- More detailed bedside teaching on recoil of the chest: the code leader or CPR coach should visually watch for subtle leaning on the chest as compressors fatigue rather than relying only on rate/depth.
- Preference that the best CPR feedback devices are integrated into the defibrillator rather than standalone devices, because they are easier to use and can display rate, depth, rhythm, and now ventilation parameters in one place.
- The head-up CPR discussion is more skeptical: it emphasizes that head-up CPR is really a bundle of elevation + Impedence Threshold Device (ITD) + mechanical CPR, that the animal data are much stronger than the human data, and that Lucas migration on an incline is a major practical problem.
- The mechanical CPR should not be used routinely if you can already provide high-quality manual CPR, even during short transports.
- Mechanical CPR has a major learning curve and should ideally be applied within about 10 seconds, with “pit-stop” style team training.
- Use mechanical CPR as an academic/training tool during selected resuscitations so teams can practice rapid deployment for the situations where it may truly matter.
POCUS Pulse Check [Link is to a Google Search]
Monitoring, resuscitation targets and ventilation
- A more nuanced approach to ETCO₂: do not chase a single number; interpret it in context, and specifically be cautious that narrow-complex PEA with a high ETCO₂ may represent pseudo-PEA rather than true pulselessness. CO₂ retainers, bag-mask leaks / lack of a closed system, and uncertain prolonged downtime can all distort the value.
- If present, an arterial line is considered the gold standard physiologic monitor; one target is diastolic pressure >30 suggesting decent CPR, while sudden increases may suggest ROSC and very low values suggest poor prognosis.
- Some systems, especially in Europe, may target MAP during arrest rather than only diastolic pressure.
- Ventilation feedback devices are emerging and may be the next major frontier, displaying both ventilatory rate and tidal volume.
- Question the evidence basis for the traditional 500–600 mL tidal volume target; active investigation into whether 300–400 mL may be preferable.
- A practical ventilation pearl is compression-adjusted ventilation (CAV): using about 10–12 compressions per breath to maintain one breath every six seconds.
- Discussion of early use of a ventilator in CPR mode to control asynchronous ventilation during arrest rather than relying on a manual bagger.
Defibrillation
- A common defibrillation mistake is bad pad position, especially placing the lateral pad too anterior and too inferior, effectively “defibrillating the spleen.”
- A major new concept is that for VF, current matters more than energy, and Antero-Posterior (AP) pad position may be physiologically superior to Antero-Lateral (AL) because it delivers more current through the ventricles.
- Distinguish Atrial Fibrillation (AF) cardioversion from VF defibrillation: AP has shown to be more effective than AL in AF because of the relevant atrial myocardium, whereas AP may be better for VF because recurrent VF often arises from more posterior-inferior ventricular myocardium.
- Practical logistics for AP defibrillation: teams can place AP pads with a quick log roll during ongoing resuscitation and some resuscitations now start AP first.
- After the first few failed shocks, POCUS can be used to check whether the heart is actually sandwiched between the pads, not for the first shock, but to optimize subsequent shocks.
- A challenge to the fixed two-minute cycle: most refibrillation happens within about 30 seconds, not two minutes, and argue that earlier re-shocking when refibrillation is seen may be more physiologic.
- Related to that, see-through CPR algorithms can filter out compression artifact and allow earlier recognition of refibrillation during ongoing CPR.
- The shock-energy discussion is updated toward a high-energy/high-current upfront strategy, e.g. repeatedly using the higher energy settings available on a given defibrillator rather than escalating slowly from lower energies.
- For hirsute patients, the practical “wax job” trick: apply pads, rip them off to remove hair, then place a fresh set or manual pressure augmentation over the pads to reduce transthoracic impedance.
Refractory and recurrent VF, Dual Sequence Defibrillation
- For refractory VF, a much more granular taxonomy: pragmatic refractory VF, true shock-refractory VF, and recurrent VF, and emphasize that recurrent VF should not automatically be assumed to be purely a drug/LAD problem rather than a defibrillation problem.
- The Dual Sequence Defibrillation (DSED) [Link is to a Google Search] rationale is updated: it likely works not because it is simply “more juice,” but because it provides more homogeneous current distribution across the ventricle and because the second shock sees a different myocardial state/rhythm milliseconds after the first shock.
- In trained systems, DSED did not worsen CPR quality, with chest compression fraction remaining similar across DSED, vector change, and standard groups.
- DSED and vector change are not equivalent interventions, and if two defibrillators are available, the clear preference is DSED over vector change.
- Early DSED discussion: emerging European work suggesting a possible signal that earlier DSED, even after the first failed shock, may be beneficial, contrary to the idea that early DSED may be harmful.
- Stellate Ganglion block is a fairly simple procedure using PoCUS [Link is to a Google Search] similar to placing a central line.
The Big Picture: What actually improves outcomes
Cardiac arrest care is defined less by what we add and more by how well we execute what already matters. The latest guideline-informed perspective reinforces that survival is driven by a series of interdependent steps, each of which must be optimized.
The chain of survival now explicitly includes:
- Early recognition and activation – Dispatcher recognition of arrest has improved, some systems have adopted video-assisted dispatcher coaching, citizen-responder smartphone activation has increased early CPR/AED retrieval, and AED registries integrated into dispatch platforms can shorten time to first shock. Emerging real-world pilots using drone-delivered AEDs suggest meaningful time savings in VF—because in VF, seconds are physiology.
- High-quality CPR
- Early defibrillation
- Advanced resuscitation
- Post-arrest care
- Recovery and survivorship
The greatest impact comes from the earliest links—rapid activation, bystander CPR, and early defibrillation. By the time a patient reaches the ED without ROSC, prognosis is already significantly diminished, underscoring that ED care is only one part of a larger system.
High-quality CPR: Not so simple
High-quality CPR is one of the only interventions with a clear and consistent relationship to survival and neurological outcome. Even experienced clinicians frequently perform CPR poorly. CPR is physically demanding, and degradation in performance happens rapidly. Even within 45 seconds, compression quality begins to decline, which is why switching compressors every two minutes is not just recommended—it is essential. What is often under-appreciated is that CPR is not simply about generating movement—it is about generating forward blood flow. Every component—rate, depth, recoil—directly influences cardiac output during arrest. If any of these are suboptimal, perfusion to the heart and brain falls.
In practice, this means that the team leader must actively monitor CPR as a primary intervention, not assume it is being done correctly. High-performing teams treat CPR like a continuously titrated therapy. We often teach “rate 100–120, depth 5–6 cm, full recoil,” but those are surrogates. The real goal is uninterrupted perfusion.
Which CPR targets have the strongest causal plausibility?
Aortic diastolic pressure/arterial lines #1
If you rank physiologic targets by direct mechanistic link to ROSC and defibrillation success, aortic diastolic blood pressure is the most causally plausible bedside surrogate for CPP—when you have an arterial line. Diastolic pressure directly reflects the pressure gradient driving coronary blood flow, and both animal and human physiologic data support the association between higher diastolic pressures during CPR and higher ROSC likelihood. In practical terms, if an arterial line is present, many experienced resuscitationists aim for diastolic BP ≥25–30 mmHg (often higher if achievable) for whether CPR is generating meaningful myocardial perfusion.
The operational nuance for placing an arterial line is staffing and opportunity cost. In a lean resus (one physician and one nurse), arterial line placement can be counterproductive if it distracts from compressions, defibrillation timing, and ventilation discipline. With adequate personnel, an a-line can serve three high-yield roles:
- Objective CPR quality feedback
- Differentiation of pseudo-PEA/low-flow states from true no-flow
- A rational framework for vasopressor strategy (treat a measurable perfusion deficit rather than giving blind doses)
Pitfall: Treating an arterial line like a life-saving intervention in itself. The line is a monitor—not a therapy—and it must never cost compression quality or pause time.
End-Tidal CO₂ monitoring in cardiac arrest
ETCO2 has strong physiologic plausibility because it reflects pulmonary blood flow and thus cardiac output generated by compressions. Higher ETCO₂ generally correlates with better perfusion and higher probability of ROSC, and a sudden sustained rise can signal ROSC. However, ETCO₂ is indirect and confounded by ventilation, airway problems, lung pathology, and metabolic state. It is best used as a trend and a quality monitor rather than a rigid interventional endpoint.
Compression fraction is foundational because it preserves CPP. It is not a “physiologic metric” in the same way, but it is causally upstream: if compression fraction is low, neither diastolic pressure nor ETCO₂ can be trusted to improve meaningfully.
Pearl: If you can measure only one physiologic CPR target, diastolic pressure has the strongest causal plausibility as a surrogate for CPP. ETCO₂ is extremely useful, but it is an indirect surrogate and must be interpreted in context.
End-tidal CO₂ confounders:
- Airway leaks (BVM vs intubation)
- Baseline CO₂ retention
- Duration of arrest
- Quality of CPR
For example, a patient with chronically elevated CO₂ may have misleadingly high values, while a prolonged downtime may produce low values despite adequate CPR. The key clinical application is to interpret ETCO₂ in context, rather than using it as a standalone decision-making tool.
