מתמחים - האיגוד הישראלי לרפואה דחופה

In this episode, Sam Ashoo, MD and Dr. Dana Klavansky, MD discuss the March 2026 Emergency Medicine Practice article, Emergency Department Evaluation and Management of Severe Traumatic Brain Injury

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Sam Ashoo, MD, FACEP,  is board certified in emergency medicine and clinical informatics. He serves as EB Medicine’s editor-in-chief of interactive clinical pathways and FOAMEd blog, and host of EB Medicine’s EMplify podcast. Follow him below for more…

The post PODCAST: Severe Traumatic Brain Injury witih Dr. Dana Klavansky first appeared on האיגוד הישראלי לרפואה דחופה.

Maximize your commute with the new Core EM Modular CME Course, featuring the most essential content distilled from our top-rated podcast episodes. This course offers 12 audio-based modules packed with pearls! Information and link below.

Course Highlights:

Clinical Paradox: Congestive symptoms (pulmonary edema, JVD, peripheral edema) in the setting of a hyperdynamic, supranormal cardiac function.

Hemodynamic Criteria:

Cardiac Index (CI): >4.0 L/min/m2.

Cardiac Output (CO): >8 L/min.

Systemic Vascular Resistance (SVR): Pathologically low (vasodilated or shunted state).

The “Warm” Phenotype: Unlike standard HFrEF/HFpEF (often “Cold and Wet”), HOHF presents as “Warm and Wet” due to low SVR and bounding pulses.

Primary Insult: Decreased SVR (either via peripheral vasodilation or arteriovenous shunting).

Effective Arterial Blood Volume: Paradoxically low despite high total CO.

Neurohormonal Cascade:

Activation of Renin-Angiotensin-Aldosterone System (RAAS).

Increased Sympathetic Nervous System tone.

Increased Antidiuretic Hormone (ADH) secretion.

Resultant State: Avid renal salt and water retention leading to massive plasma volume expansion.

Cardiac Response: Chronic volume overload → eccentric remodeling → chamber dilation → eventual secondary myocardial failure/dilated cardiomyopathy.

Hyperthyroidism/Thyrotoxicosis:

Direct T3 effects: increased chronotropy/inotropy.

Indirect effects: metabolic byproduct accumulation causing peripheral vasodilation.

Myeloproliferative Disorders:

High cell turnover and increased oxygen consumption drive compensatory CO increase.

Sepsis (Hyperdynamic Phase):

Cytokine-mediated global vasodilation.

Note: Often transient; may transition to sepsis-induced myocardial depression.

Arteriovenous Fistulas (AVF) / Malformations (AVM):

Most Common Cause: Iatrogenic AVF for Hemodialysis (ESRD population).

Bypasses high-resistance capillary beds, dumping arterial blood directly into venous circulation.

Chronic Liver Disease (Cirrhosis):

Formation of “spider angiomata” and internal AV shunts.

Impaired clearance of endogenous vasodilators (e.g., Nitric Oxide).

Thiamine Deficiency (Wet Beriberi):

Accumulation of pyruvate/lactate → systemic vasodilation.

Histopathology: Vacuolation, myofiber hypertrophy, and interstitial edema.

Chronic Lung Disease:

Hypoxia/Hypercapnia-driven systemic vasodilation.

Concomitant pulmonary HTN (RV remodeling) but preserved/high LV output.

Others: Paget’s disease of bone (extensive micro-shunting), Carcinoid syndrome, Mitochondrial diseases, Acromegaly, Erythroderma.

Acute Phase:

Immediate ↓ SVR.

↑ Stroke volume and Heart Rate (SNS-mediated).

Endothelial shear stress → Nitric Oxide release → further arterial dilation.

Subacute Phase (Days to 2 Weeks):

RAAS-driven volume expansion.

↑ Right Atrial, Pulmonary Artery, and LV End-Diastolic Pressures (LVEDP).

Natriuretic peptide surge (BNP/ANP) peaks around Day 10.

Chronic Phase (Weeks to Months):

Adaptive hypertrophy.

Decompensation occurs when dilation exceeds contractility limits.

Nicoladoni-Branham Sign (Pathognomonic for Shunt-driven HOHF):

Maneuver: Manually compress the AVF (or inflate cuff to >50 mmHg above SBP) for 30 seconds.

Positive Result: Reflexive bradycardia or a transient rise in systemic BP.

Significance: Confirms the shunt is a major contributor to the cardiac workload.

Peripheral Pulse Assessment:

Water Hammer Pulses: Rapid upstroke and collapse.

Quincke’s Pulse: Visible capillary pulsations in the nail beds.

Traube’s Sign: “Pistol-shot” sounds auscultated over the femoral arteries.

Volume Status: Rales, S3 gallop, peripheral edema (standard HF signs).

Left Ventricle: Hyperdynamic function; EF typically >60%.

Left Atrium: Significant dilation (Left Atrial Volume Index >34 mL/m2; Case study noted 72 mL/m2).

IVC: Plethoric with minimal respiratory variation.

Doppler: High flow velocities across the AV access if applicable.

BNP/NT-proBNP: Often markedly elevated (e.g., >70,000 in severe cases), though mean values in literature hover around 700–800 pg/mL.

Hematology: CBC to evaluate for severe anemia (trigger for HOHF if Hgb<7–8 g/dL) or myeloproliferative markers.

Endocrine/Metabolic: TSH (Thyrotoxicosis), Serum Thiamine (Beriberi), LFTs (Cirrhosis).

Diuresis: Aggressive IV loop diuretics (Bumetanide/Furosemide).

Ultrafiltration: Preferred in ESRD patients failing to respond to dialysis or with refractory congestion.

Vasodilator Caution: Avoid aggressive Nitroglycerin or ACE-inhibitors initially.

Rationale: Baseline SVR is already pathologically low; further reduction may precipitate profound hypotension/circulatory collapse.

Anemia: Transfuse to goal Hgb>7–8 g/dL to reduce demand.

Beriberi: High-dose IV Thiamine (100–500 mg).

Thyrotoxicosis: Beta-blockers (Propranolol) + Antithyroid meds (PTU/Methimazole).

Closure of Accessory Sites: If multiple fistulas exist, close the non-dominant/unused sites.

Flow Reduction (Banding): Surgical narrowing of the fistula to target flow <600 mL/min.

RUDI Procedure: Revision Using Distal Inflow (moving inflow to a smaller, more distal artery).

Ligation: Complete closure of the AVF.

Note: Requires bridge to Tunneled Dialysis Catheter or AV graft (higher resistance than fistulas).

The “Normal EF” Trap: Do not be reassured by an EF of 55–65%; in the context of pulmonary edema and high CO, this is potentially HOHF.

Pulse Pressure: Look for a wide pulse pressure (e.g., 180/60) as a marker of low SVR.

ESRD Logic: If an ESRD patient is “wet” immediately after HD, the problem is likely flow (AVF), not just fluid.

The post PODCAST: High-Output Heart Failure first appeared on האיגוד הישראלי לרפואה דחופה.

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…

Podcast production, sound design & editing by Anton Helman; Voice editing by Erik Krosby

Written Summary and blog post by Anton Helman March, 2026

Cite this podcast as: 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 March 27, 2026

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.

Chain of Survival

CPR

Monitoring, resuscitation targets and ventilation

Defibrillation

Refractory and recurrent VF, Dual Sequence Defibrillation

Epinephrine

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:

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 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.

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:

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.

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:

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.

A persistently low ETCO₂ should trigger one question first: Is this a CPR quality problem, or a physiology problem?
If ETCO₂ is <10–15 mmHg:

Falsely low ETCO₂ can result from hyperventilation, excessive tidal volumes increasing intrathoracic pressure, poor compressions, severe PE, low metabolic CO₂ production in prolonged arrest, airway leaks/disconnections, or severe obstructive lung disease. Falsely elevated ETCO₂ can occur with hypoventilation, bicarbonate administration (transient CO₂ load), ROSC, or certain V/Q mismatch patterns.

Pitfall: ETCO₂ used as a discreet target is a common pitfall. Rather ETCO2 is a trend monitor. Use it to detect deterioration in perfusion, guide CPR optimization, and identify ROSC.

Key recurring problems include:

Each of these has a direct physiologic consequence. For example, leaning prevents ventricular filling during recoil, reducing preload. Incorrect rate disrupts optimal coronary perfusion pressure. Hyperventilation increases intrathoracic pressure, impairing venous return.

CPR errors are cumulative. Multiple small deviations can combine to produce profoundly ineffective circulation, even when CPR appears “acceptable” at a glance.

When CPR quality was first objectively measured in large studies, no system was consistently delivering high-quality CPR. Only after introducing measurement and feedback did performance improve.

In practical terms, this has several implications:

Interruptions in CPR are physiologically devastating. Coronary and cerebral perfusion pressures fall rapidly during pauses, and it takes multiple compressions to rebuild them. Minimizing interruptions is not about rushing—it is about anticipation.

Effective teams:

Ultrasound pulse checks can improve accuracy if performed with strict discipline. The value is not “more data”; it is faster confirmation of pulsatility at a known anatomic target. The danger is that ultrasound becomes a pause-extending distraction. The probe must be ready, positioned during compressions, and used to confirm flow during a brief pause—then compressions resume immediately. If interpretation requires longer thinking, capture/record a short clip and interpret after compressions restart.

Pearl: To minimize CPR interruption record the PoCUS pulse check for 3-5 seconds and resume CPR immediately, then interpret the recording

Feedback devices are appealing because they target something we know matters—compression quality—but the evidence is mixed and stronger for CPR process metrics than for survival. Real-time audiovisual feedback can modestly improve compression rate, depth, recoil, and sometimes compression fraction. Metronomes can help prevent drift in rate but do not ensure depth or recoil and have not convincingly improved outcomes alone. Analogue tactile “clicker” devices show promising signals in low-certainty data, likely because they enforce adequate depth with an unmistakable cue.

In practice, the most defensible role for feedback devices is within a quality improvement program. Measuring CPR quality across arrests, reviewing performance, identifying recurring failure modes, and retraining accordingly is where devices may produce system-level benefit. Even sensor-only measurement can improve performance through observation effects—teams compress better when they know compressions are being measured.

Head-up CPR has a physiologic rationale that is easy to like: elevating head and thorax may reduce intracranial pressure and improve cerebral venous drainage, potentially improving cerebral perfusion. But the concept is usually bundled with strategies to augment forward flow (active compression–decompression CPR, impedance threshold devices). Without those adjuncts, tilting could reduce venous return and compromise cardiac output.

Operationally, head-up CPR is difficult to do well with manual compressions. Maintaining consistent depth, recoil, and compression fraction while the patient is tilted is challenging. For practical reasons, head-up CPR typically needs to be paired with mechanical CPR to provide consistent compressions while allowing controlled elevation. The evidence base remains early and limited, with feasibility studies and small datasets—often bundled interventions—making it hard to isolate which component drives any observed signal. The strongest evidence for head-up CPR comes from animal studies, where combining head elevation with an impedance threshold device and mechanical CPR shows clear improvements in cerebral perfusion and intracranial pressure. However, they are explicit that translating these results into humans has been problematic, and that human studies are small and conflicting, with no convincing demonstration of improved survival. Although one center (Minnesota) has reported success with head-up CPR, other systems have not been able to replicate those results, raising concern that outcomes may depend heavily on highly specialized protocols and early implementation that are difficult to reproduce.

Mechanical CPR is not recommended for routine use, but it has clear roles in specific situations:

A key limitation is that application of the device can cause significant interruptions if not performed efficiently. There is a clear learning curve, and teams must train to apply devices rapidly (ideally within 10 seconds).

Ventilation mismanagement is one of the most common iatrogenic harms during cardiac arrest. Hyperventilation increases intrathoracic pressure, reduces venous return, decreases CPP, and increases intracranial pressure—reducing cerebral perfusion. Even experienced providers hyperventilate during the adrenaline of a code. The recommended approach remains simple but hard to execute: once an advanced airway is in place, provide one breath every 6 seconds (10/min), deliver each breath over ~1 second, and use only the tidal volume needed for visible chest rise. Over-ventilation is often not recognized in real time, which is why ventilation feedback devices and structured strategies are an important future direction.

Instead of timing breaths by counting seconds (which often fails under stress), synchronize ventilation with compressions using a 12:1 compression-to-ventilation ratio (one breath after every 12 compressions). At a compression rate near 120/min, this naturally generates ~10 breaths/min and reduces drift into hyperventilation. It anchors behavior to the rhythm of CPR rather than the wall clock.

Ventilation strategy during arrest is a major area of future research. The OPTIVO trial (Optimized Ventilation in Cardiac Arrest) is designed to evaluate whether a more physiologically optimized ventilation strategy—controlling rate and volume to minimize intrathoracic pressure and preserve venous return—improves outcomes compared with conventional practice. In parallel, ventilation feedback devices that provide real-time rate and tidal volume cues may reduce hyperventilation during chaotic resuscitation. Additionally, the evidence for the traditional 500–600 mL tidal volume target is weak; there are active investigations into whether 300–400 mL may be preferable. Early use of a ventilator in CPR mode to control asynchronous ventilation during arrest has a strong physiologic rationale but requires further study.

Pearl: If you can’t reliably deliver one breath every 6 seconds, use compression-adjusted ventilation (12:1) to “hard-wire” the correct rate into the resuscitation rhythm.

Defibrillation is deceptively simple—push a button and shock—but success depends on whether current actually traverses myocardium and whether perfusion has primed the heart to respond. Many “by the book” failures are not failures of the algorithm, but failures of technique and choreography.

Peri-shock pause is the major culprit: stopping compressions too early, charging after the pause begins, delaying compressions after the shock, and allowing rhythm checks to sprawl into extended hands-off time. Technical errors also matter: poor pad adhesion, pads placed on hair or moisture, incomplete chest exposure, or pad placement that does not maximize current through ventricular myocardium. A final strategic mistake is repeating identical shocks indefinitely without escalating defibrillation conditions—vector change, pad repositioning, energy escalation, or advanced strategies in refractory VF.

The two-minute CPR cycle is a practical teaching tool, not sacred physiology. Recurrent VF often occurs early after a shock within 30 seconds. Where rhythm filtering allows detection of refibrillation during compressions, there is physiologic plausibility to re-shock promptly when VF is clearly present rather than waiting an arbitrary full cycle. This is not stacked shocks with long pauses—it is the idea that we should avoid unnecessary time in VF while preserving compression fraction.

Emerging evidence suggests that anterior–posterior (AP) pad placement may deliver more current through the ventricles compared to anterior–lateral (AL). This is particularly relevant in ventricular fibrillation, where the goal is to deliver current through the ventricular myocardium. In contrast, atrial fibrillation cardioversion targets the atrium, explaining why AL may be ore effective for termination of atrial fibrillation.

Practically, AP placement can be achieved with minimal interruption:

A key conceptual shift is understanding that current—not energy—is what matters in defibrillation. This brings pad placement into focus. Incorrect placement, particularly placing the lateral pad too low or anterior (effectively shocking the spleen!), can result in ineffective current delivery. Many pad placements effectively “miss the heart,” delivering current through non-cardiac structures.

Pearl: Start with the fastest, cleanest, most consistent pad placement that preserves compression fraction. Escalate to vector change deliberately when shocks fail—without paying for it in pause time. Some systems start with AP positioning which appears to maximize current through the heart when compared to AL pad positioning.

In hairy patients, poor pad adhesion increases impedance and reduces effective current delivery. The key is to solve the contact problem without delaying shocks.

Pearl: Manually applying pressure to the pads in hirsute and/or sweaty patients during defibrillation is safe for the provider and increases current, the key factor in effective defibrillation

The 2025 AHA Guidelines provide no recommendations after 3 shocks, epinephrine and amiodarone are given in VF.

The traditional two-minute CPR cycle is increasingly questioned. Most patients who refibrillate do so within 30 seconds, not two minutes. This raises concern that waiting a full cycle before re-shocking may delay effective therapy.

While evidence is not definitive, the physiologic argument supports:

Dual sequential external defibrillation (DSED) uses two defibrillators and two pad sets to deliver two shocks in rapid sequence. This not simply “more joules,” but improved myocardial coverage through multiple vectors and a potential priming effect where the first shock alters the VF substrate, increasing susceptibility to the second shock delivered milliseconds later.

A major controversy is whether DSED harms CPR quality by introducing complexity and longer pauses. In the DOSE-VF trial, chest compression fraction was similar across all groups, including DSED. This suggests that, in trained systems, DSED can be implemented without compromising CPR quality, which is critical since CPR quality is strongly tied to outcomes. The practical implication is that DSED is a training problem, not an unavoidable pause problem: if your system cannot do it without prolonged hands-off time, it may not be worth it; if it can be integrated cleanly, it becomes a preferred escalation strategy.

DOSE-VF trial is a high quality sizeable randomized trial comparing:

The trial demonstrated that both vector change and DSED improved outcomes compared to standard defibrillation, including higher rates of ROSC and improved survival. While both vector change and DSED performed better than standard care, DSED is favored when feasible according to our experts.

Traditionally, DSED has been reserved for refractory VF after three failed shocks. However, there exists emerging data suggesting that earlier use of DSED may be beneficial. There are several small European studies showing a signal that early DSED—even after the first failed shock—might improve outcomes, and importantly, that early use does not appear harmful. Many institutions in North America already use DSED after the second shock, while others are waiting for more data before moving it as early as after the initial shock. This challenges the traditional “late rescue therapy” mindset and suggests that DSED may be more effective when used before prolonged ischemia and myocardial deterioration occur.

Stellate ganglion block is grounded in a simple physiologic idea: sympathetic overdrive fuels electrical instability. In prolonged refractory VF or electrical storm physiology, the myocardium is often bathed in catecholamines—from endogenous stress response and from exogenous epinephrine. This sympathetic surge lowers arrhythmia threshold and can perpetuate recurrent or refractory VF despite shocks and antiarrhythmics.

The stellate ganglion provides major sympathetic input to the heart. Blocking it produces a rapid temporary chemical sympathectomy, aiming to reduce arrhythmogenic drive and stabilize the myocardium so defibrillation and perfusion strategies can succeed. Observational evidence and systematic reviews suggest high rates of arrhythmia suppression or reduction in electrical storm, with low rates of serious complications. It is best thought of as a bridge therapy—buying time for definitive management such as PCI, ECMO, or ablation.

SG = Stellate Ganglion, CA = Carotid Artery SCM = Sternocleidomastoid

Complications are uncommon. Transient Horner’s syndrome and hoarseness may occur. Serious complications (vascular injury, pneumothorax, major bleeding) are rare with ultrasound guidance. Evidence is largely observational and protocols vary, but the physiologic rationale is coherent and the bedside feasibility is high in trained hands.

Epinephrine works because it raises aortic diastolic pressure via alpha-mediated vasoconstriction, increasing CPP and the probability of ROSC. The problem is that while epinephrine improves ROSC and survival to hospital admission, it has not consistently improved neurologically intact survival in a large, definitive way. That tradeoff matters most in shockable rhythms where defibrillation is the primary therapy and excessive catecholamine exposure may worsen electrical instability.

Guideline dosing remains 1 mg IV/IO every 3–5 minutes. High-dose epinephrine has not shown benefit and may cause harm. The nuanced bedside discussion is about rhythm-specific strategy: in VF, many clinicians stop epinephrine after 2–3 doses if VF remains refractory or recurrent, especially when catecholamine-driven instability is suspected. In PEA/asystole, early epinephrine appears more clearly associated with improved ROSC, and continued dosing is reasonable while aggressively searching for reversible causes—though prolonged futile resuscitations should still trigger a reassessment of goals and likelihood of meaningful outcome.

Pitfall: Continuing epinephrine for multiple doses without addressing reversible causes or without reconsidering whether catecholamines are perpetuating instability in refractory VF.

IM epinephrine is being explored as a way to deliver earlier epinephrine when IV access is delayed, particularly in the prehospital setting. Observational and pilot data suggest shorter time to first dose and signals for improved ROSC and early survival, especially in non-shockable rhythms, with uncertain impact on neurologically intact survival. The physiologic concern is absorption: in a low-flow arrest state, skeletal muscle perfusion is reduced, making IM uptake potentially delayed or unpredictable. The practical stance is cautious optimism: IM may be a bridge when IV/IO is delayed, but it should not replace rapid vascular access until randomized outcome data clarify its effect.

The AHA guideline direction emphasized here is a practical hierarchy: IV preferred, IO as backup. The reason is not that IO never works, but that IO reliability and pharmacokinetics may be less consistent than previously thought, and RCTs have not shown superiority despite perceived faster placement. Malposition and silent failure are key concerns.

Where PoCUS adds real value is confirmation of IO placement. Doppler ultrasound during flush can confirm medullary flow quickly without interrupting CPR, identifying nonfunctional IOs that otherwise would be assumed to work.

Pearl: If you’re using IO in arrest, especially when expected drug effects are absent, PoCUS Doppler confirmation can convert IO from a hopeful access point to a verified delivery route.

The post PODCAST: Cardiac Arrest Update: Beyond the 2025 Guidelines Part 1: CPR, Defibrillation and Ventilation first appeared on האיגוד הישראלי לרפואה דחופה.

Chris and Wade talk about sepsis.

For EMT and AEMT classes, check out IdahoMedicalAcademy.com and use code "Summit" at checkout for 10% off.

Welcome to the Basically EMT podcast! We are very excited to be able to bring this new content to all of you and hope that you find it as fun and as informative as we do. With so many outlets for media, it can be hard to find accurate, up-to-date, and digestible material. With basically EMS we hope to be your go to station to listen for basic EMS information. Listen as our highly knowledgeable guests talk about their experiences in the field and share their expertise.

The post PODCAST: SEPSIS for EMS first appeared on האיגוד הישראלי לרפואה דחופה.

Kate Lazier on a case of fever without a source (1:13)

Andrew Petrosoniak on chest tubes in trauma part 2 (15:59)

Adrianna Roweon the challenges of recognition and management of medetomidine withdrawal (28:49)

Justin Morgensternon why the PECARN c-spine rule may be dangerous (36:19)

Zach Cantor on paramedic handover done right (48:45)

Sara Gray & Katie Lin on coaching the em mind part 1: physiology – sleep, nutrition and exercise (59:16)

Podcast production, editing and sound design by Anton Helman

Podcast content, written summary & blog post by Anton Helman, March, 2026

Cite this podcast as: Helman, A. Lin, K. Lazier, K. Petrosoniak, A. Morgenstern J. Cantor, Z. Gray, S. EM Quick Hits 71 – EMC²: Fever Without a Source, Coaching the EM Mind Part 1, Traumatic Pneumothorax Part 2, PECARN C-spine Rule, Medetomidine Withdrawal, EMS Handover. March, 2026. https://emergencymedicinecases.com/em-quick-hits-march-2026/. Accessed March 11, 2026.

High-risk infectious diagnoses to consider

Inflammatory diagnoses

Giant cell arteritis and other vasculitites

Malignancy

Leukemia / blast crisis

Toxicologic / endocrine diagnoses

West Nile Virus pearls

Fever of Unknown Origin (as apposed to Fever Without a Source)

If you haven’t already, listen to Part 1 first where Dr. Petrosoniak talks about the following…

Needle Decompression in the ED for traumatic pneumothorax

Physiology-First Approach to Traumatic Pneumothorax

Medetomidine, a veterinary sedative and potent non-selective alpha-2 adrenergic agonist pharmacologically similar to clonidine and dexmedetomidine, has increasingly been identified as an adulterant in the unregulated opioid supply and is now emerging as an important cause of withdrawal syndromes presenting to emergency departments.

Acute toxicity from alpha-2 agonists typically produces sedation and sinus bradycardia, and although naloxone may reverse concomitant opioid-induced respiratory depression, it does not reverse sedation related to alpha-2 agonists or benzodiazepines that may also be present in contaminated drug supplies.

The more challenging clinical presentation is medetomidine withdrawal…

Key features:

Complications reported:

Patients using unregulated drugs with:

The goal of medetomidine withdrawal treatment is to restore alpha-2 agonism

Clonidine

Dexmedetomidine infusion

Use antidopaminergic agents

Note that ondansetron is often ineffective.

A recent multicenter study derived and validated a pediatric c-spine decision rule for children with blunt trauma presenting to trauma centers, identifying several high-risk clinical features associated with a substantially increased likelihood of cervical spine injury.

High-risk findings include:

Additional intermediate-risk features include:

Despite the methodological riggor of the study, the resulting rule demonstrates only moderate sensitivity, raising concern that a clinically meaningful proportion of injuries could be missed, while the positive predictive value remains extremely low given the rarity of cervical spine injury even in high-risk trauma populations.

Importantly, the rule was derived in pediatric trauma center cohorts with far higher baseline imaging rates than most emergency departments, and has not yet undergone adequate external validation, comparison with clinician judgment, or implementation studies assessing its real-world impact on imaging practices.

In the opinion of our guest expert, routine application of the rule outside highly selected trauma settings may paradoxically increase cervical spine imaging, potentially exposing large numbers of children to unnecessary radiation without improving diagnostic accuracy.

Communication during prehospital-to-emergency department handover represents a critical but frequently under-recognized patient safety intervention, with observational studies demonstrating substantial information loss during transitions of care.

Research suggests that a significant proportion of key clinical information is either omitted or not retained during handover, with frequent interruptions, parallel conversations, and premature patient transfer contributing to incomplete communication and potential downstream impacts on patient care.

Evidence consistently demonstrates that handovers are most effective when they are brief, structured, and delivered before patient transfer, allowing receiving teams to focus attention on the information being communicated.

The IMIST-AMBO framework provides a standardized structure for handover:

IMIST

AMBO

Bottom Line -> Better EMS handover → fewer interruptions, clearer communication, improved patient care.

Emergency medicine places clinicians in a uniquely demanding cognitive and physiologic environment characterized by shift work, sleep disruption, high cognitive load, and repeated exposure to emotionally stressful situations. Over time, these stressors can degrade both clinical performance and personal wellbeing, making deliberate attention to physiologic needs an essential component of professional sustainability.

Emergency medicine practice exposes clinicians to sustained physiologic and psychological stressors, particularly related to shift work, which is associated with increased risk of metabolic syndrome, cardiovascular disease, malignancy, and mental health disorders.

In addition to long-term health risks, sleep disruption from rotating shift schedules impairs cognitive performance, concentration, reaction time, and clinical decision-making, with fatigue-related motor vehicle collisions representing an additional hazard during post-shift commutes.

Strategies to mitigate these effects include:

Early indicators of declining resilience often emerge in four physiologic domains: sleep, physical conditioning, nutrition, and stress regulation. Warning signs may include falling asleep during commutes or routine activities, progressive deterioration in physical fitness or health metrics, irregular or inadequate nutrition during shifts, and increasing feelings of overwhelm, irritability, or dread before work. Importantly, these changes often develop gradually and may be more readily recognized by colleagues or family members before clinicians recognize them themselves.

Several evidence-informed scheduling principles may help mitigate these effects. Whenever feasible, schedules should incorporate flexibility that allows clinicians to align shifts with their chronotype, recognizing that individuals naturally differ in their sleep–wake preferences.

Because sleep disruption is unavoidable in emergency medicine, clinicians benefit from intentionally optimizing sleep environments and routines. Practical measures include maintaining a dark, cool, and quiet sleeping environment, using blackout blinds, eye masks, earplugs, and white-noise devices when necessary. Strategic pre-shift napping before night shifts, minimizing caffeine intake in the hours preceding sleep, and limiting exposure to bright light before planned sleep periods may also improve sleep quality. Developing consistent routines around sleep—even when schedules vary—can significantly improve restorative sleep over time.

Episode 207 Deep dive into sleep strategies for shift workers

Regular physical activity plays a critical role in maintaining both physical and cognitive resilience. Exercise has been shown to improve attention, memory, mood regulation, and stress tolerance, while also reducing long-term risks of cardiovascular disease and dementia. Even modest and consistent exercise routines—such as brief daily workouts or incorporating activity into existing routines—can yield meaningful physiologic and psychological benefits. Importantly, sustainable habits often begin with small, achievable goals rather than ambitious but unsustainable lifestyle changes.

Nutrition is an often overlooked determinant of physician performance, yet it plays a critical role in maintaining cognitive function, metabolic health, and circadian stability, all of which are challenged by shift work. Irregular schedules and busy clinical environments frequently lead emergency physicians to skip meals or rely on highly processed foods, which can produce fluctuations in blood glucose that contribute to fatigue, irritability, and impaired concentration.

Bottom Line – > Ultimately, maintaining personal physiologic health should be viewed not as optional self-care but as a professional responsibility essential for sustaining high-quality emergency care over the course of a long career.

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Japanese Airway Study: Kubo A, Kunitatsu K, Nakashima T, Horitani R, Kajimoto Y, Inoue S, Hironishi M. Association between endotracheal intubation and outcomes of nonshockable out-of-hospital cardiac arrest in Japan. BMC Emerg Med. 2025 Sep 24;25(1):185. doi: 10.1186/s12873-025-01341-6. PMID: 40993541; PMCID: PMC12462024.

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In January, OpenAI, developer of ChatGPT, launched ChatGPT Health, one of many patient-facing generative artificial intelligence (AI) tools in various stages of development.

In January, OpenAI, developer of ChatGPT, launched ChatGPT Health.

From educating patients on women’s sexual health and hip replacement surgery to generating postoperative instructions and digitizing informed consent, the potential medical applications of generative AI tools for the public are vast. In general, their goal is to increase patients’ comprehension of complex medical information and, in the case of ChatGPT Health, provide personalized information based on individual users’ own data. In the not-too-distant future, some experts predict new AI technologies will be able to independently make decisions about patient care.

At their most sophisticated, though, these technologies should serve as a “clinician extender,” not a clinician replacer, said cardiologist Haider Warraich, MD, a program manager at the US government’s Advanced Research Projects Agency for Health (ARPA-H) who previously helped shape digital health and AI policy at the US Food and Drug Administration (FDA).

“I hate the term AI doctor,” Warraich said. “There’s a lot more to me than what these technologies can do.”

There’s more than one reason why using an AI chatbot for health advice is not the same as consulting a physician. Recent studies have raised questions about the accuracy of health information provided by chatbots, and physicians and consumers have expressed concerns over the sharing of personal medical data with large language models (LLMs) that aren’t covered by the Health Insurance Portability and Accountability Act (HIPAA).

ChatGPT Health failed to properly triage the most and the least serious cases in what might be the first study to assess the new tool’s performance, according to an accelerated preview of the article published in late February. The authors, who tested the chatbot using vignettes written by physicians, noted that under-triage of emergency conditions may delay or preclude lifesaving treatment, while over-triage of nonurgent presentations may increase health care utilization.

But LLMs hold promise as a way of expanding access to medical expertise or, at the very least, preparing patients to make the best use of visits with their physicians. “There’s a reason patients want to use these models,” said radiation oncologist Danielle Bitterman, MD, clinical lead for data science and AI at Mass General Brigham. “It’s so hard to access health care right now.”

Of the 800 million users of ChatGPT each week, 1 in 4 seek health-related information, according to Nate Gross, MD, MBA, who leads health care strategy at OpenAI, which developed the chatbot.

“We said, ‘Hey, let’s build some differences to the product to make it a more contextually aware experience,’” as well as one with additional privacy and security connections, he recalled.

Users of “vanilla” ChatGPT, as Gross describes the forerunner of ChatGPT Health, can upload a physician’s note or copy laboratory results from their patient portal, he explained, but those bits of information lack context. “Just uploading a really short doctor’s note could be interpreted very differently if you’re age 20 or age 70.”

ChatGPT Health, on the other hand, invites users to upload all their personal health information, including laboratory test and imaging results as well as data collected by their Apple watch.

Although OpenAI consulted with hundreds of physicians from around the world to improve its models, ChatGPT Health is not designed to play doctor, Gross emphasized.

“We train our models specifically to guide patients to health care professionals for diagnosis and treatment,” he said. “We’re looking to give people information, not tell them if they’re sick, not tell them if they’re healthy. We’re a partner to the health care system in that regard.”

By late February, ChatGPT Health was not yet available to all comers; prospective users could add their name to a waitlist for using the chatbot. OpenAI declined to say how many people have used ChatGPT Health so far.

Privacy is one of users’ main concerns about ChatGPT Health and other LLMs that allow people to upload personal health information.

Elon Musk recently suggested in an X post that “[y]ou can just take a picture of your medical data or upload the file to get a second opinion from Grok,” an AI chatbot developed by his company, xAI.

Commenters were aghast at the idea. One decided to ask Grok’s opinion and posted its reply: “Grok is not HIPAA compliant, and we strongly advise against uploading sensitive medical data.”

Gross acknowledged that ChatGPT Health isn’t HIPAA compliant either. That’s not due to negligence, he pointed out, but because ChatGPT Health, like Grok, is not an entity covered by HIPAA, such as a physician or health insurance plan, or a business associate of a covered entity.

“They are not held to the same legal requirements that doctors and health care institutions are,” Bitterman said of the AI companies.

ChatGPT Health “is building on a lot of very proprivacy protections that ChatGPT already had, with additional layers of protection,” Gross said. “We wanted to set a really high bar.” For example, he noted, OpenAI will not include any ChatGPT Health conversations among the data it uses to train the LLM. And, he explained, as with ChatGPT, ChatGPT Health users can opt to make chats temporary, meaning they won’t appear in their history and ChatGPT Health won’t save them.

Even so, “those assurances may not be worth that much if companies get sold,” pointed out David Liebovitz, MD, codirector of the Institute for Artificial Intelligence in Medicine’s Center for Medical Education in Data Science and Digital Health at the Northwestern University Feinberg School of Medicine.

For now, he said, if patients asked him whether he thought they should try ChatGPT Health, he’d probably suggest “they could wait a little bit longer, when there could be more privacy-related tools.”

Even if they want to, chatbot users—especially clinically challenging patients with long, complex medical histories—can’t always upload all their medical records, Bitterman pointed out.

“It’s very hard to ensure that you have all your medical records,” she said. “Those are the missing pieces that make clinical practice hard.”

Gross acknowledged that “our health care system is very fragmented.” But, he said, if patients forget to upload records from a particular physician or hospital, their physicians’ most recent notes likely will at least mention them.

Even patients who have all the relevant information may not paint a complete picture of their situation when interacting with LLMs, concluded research published in February.

The study, led by the Oxford Internet Institute in the UK, tested whether LLMs could help individuals without medical training identify underlying conditions and choose a course of action in 10 physician-drafted health scenarios. Researchers randomly assigned 1300 participants to receive assistance from 1 of 3 LLMs or, to serve as the control, a source of their choice, which was typically Google. The 3 LLMs were ChatGPT-4o, Meta’s Llama 3, and Command R+, which was developed by Cohere, a Canada-based company.

On average, when the scientists presented the vignettes directly to the LLMs, bypassing human interaction, the chatbots correctly identified the condition 95% of the time and the appropriate course of action 56% of the time.

But when study participants presented the vignettes to the same LLMs, the chatbots correctly identified relevant conditions only about a third of the time and the appropriate course of action less than 44% of the time. The LLMs performed no better than Google did in the control group.

“The limiting factor wasn’t just the model’s medical knowledge,” coauthor Rebecca Payne, MBBS, PhD, MPH, a general practitioner at the North Wales Medical School, Bangor University, said in an email. “It was the human-AI communication loop: people providing incomplete information, the model misinterpreting key details, and, importantly, people failing to carry forward a relevant diagnostic suggestion that the model did raise during the exchange.”

Whether using an LLM or Google, study participants “tended to underestimate the severity in the vignettes we tested,” Payne said. “That raises the risk that some users may feel falsely reassured or may delay seeking care.”

Payne’s findings didn’t surprise Bitterman. “With these chatbots, it’s incumbent on the user to know what they need to provide to the model to get the best information,” she said. “Having that kind of clinical nuance requires a lot of on-the-ground training,” not just the LLMs’ training on medical literature and textbooks.

The advice she gives to patients: “Don’t take immediate action just based on what you find online. We can discuss it together.”

The result could be deadly if, say, a chatbot mistakenly told a user that they didn’t need to go the emergency department because their chest pain was due to indigestion, not a heart attack.

That’s why Payne advises patients to use chatbots only for low-stakes support, such as explaining medical terms, preparing questions for a clinician, and summarizing what they’ve been told. “LLMs currently perform best as ‘assistants/secretaries’ that help organize known information rather than generate high-stakes clinical interpretations,” she said.

Physicians are working on a number of generative AI applications for more focused, lower-stake purposes.

For urologist Gio Cacciamani, MD, the diagnosis of a loved one with a serious disease unrelated to his specialty gave him a taste of what patients face when trying to decipher scientific information.

“When it comes to something outside my field, it’s very challenging to read,” said Cacciamani, director of the Artificial Intelligence Center for Surgical and Clinical Applications in Urology at USC’s Keck School of Medicine. “That situation opened my eyes.”

Cacciamani discovered 2 types of medical information online—either “extremely readable but not certified,” such as blog posts, or “peer-reviewed, certified, but not readable at all,” mainly publications in scientific journals.

Generative AI “has the potential to bridge long-standing gaps between certified medical knowledge and patient understanding,” Cacciamani and coauthors noted in a commentary published in February.

Using the retrieval-augmented generation, or RAG, technique, which trains the LLM with a medically verified knowledge base, he developed a new tool that can translate and summarize abstracts and full articles. More than 6000 people have turned to Pub2Post, and some medical journals are using it for their social media posts, Cacciamani said.

Antonio Forte, MD, a plastic surgeon at the Mayo Clinic in Jacksonville, Florida, used RAG to develop an LLM virtual assistant for postoperative instructions.

Patients often are discharged after surgery while still experiencing the residual effects of anesthesia or painkillers, making it difficult to remember postoperative instructions, Forte said. And, he added, they frequently misplace printouts of the information. “That’s why we thought, ‘What if we got patients the ability 24/7 to have access to high-quality, medically verified information?’”

Using simulated patient interactions, testing the virtual assistant demonstrated strong technical accuracy, safety, and clinical relevance, albeit at a relatively high 11th-grade reading level, Forte and his coauthors recently reported.

And Bitterman has tested the ability of ChatGPT-4o and Llama 3.2-8B to answer patients’ questions about clinical trials with the goal of simplifying informed consent forms. In a recent study, she and her coauthors found that ChatGPT-4o was significantly more reliable and safer that Llama 3.2-8B in answering these queries.

In January, 2 federal agencies, both part of the US Department of Health and Human Services, launched initiatives focusing on digital health tools for patients with common, chronic conditions. One is designed to evaluate a regulatory pathway for digital health tools including LLMs, and the other aims to spur the development of an LLM for patients with heart failure.

The FDA, working with the Center for Medicare & Medicaid Innovation, announced the Technology-Enabled Meaningful Patient Outcomes (TEMPO) for Digital Health Devices Pilot.

According to the FDA, the voluntary pilot will evaluate a new enforcement approach “that supports digital health devices intended for use to improve patient outcomes in cardio-kidney-metabolic, musculoskeletal, and behavioral health conditions.”

The FDA has not yet authorized any LLM, Warraich said. Generative AI applications such as LLMs “present a unique challenge because of the potential for unforeseen, emergent consequences,” according to a Special Communication he coauthored in JAMA in 2024.

Today, Warraich is leading a new ARPA-H initiative whose goal is the development of new LLM systems that are ready for submission to the FDA within 2 years for authorization as medical devices. The Agentic AI-Enabled Cardiovascular Care Transformation (ADVOCATE) program “aims to transform advanced cardiovascular disease management with an agentic AI system that can provide 24/7 holistic clinical care.”

“I believe that as AI presents an opportunity to fundamentally transform what it means to be a clinician, a patient, and the relationship between them, cardiology will be at the tip of the spear…,” Warraich noted in an opinion piece published in February in the Journal of the American College of Cardiology.

The first use for technologies developed through ADVOCATE will be providing care for patients with congestive heart failure. If a patient is feeling short of breath, for example, the technology will decide if the patient should go to the emergency department and whether they might need a new prescription or a higher dose of a current medication, Warraich explained. Along with developing AI agents that can be trusted to make such changes autonomously, ADVOCATE will also support the creation of a supervisory AI “overseer” to monitor the safety and effectiveness of clinical AI agents after they’ve been deployed by health systems.

Given that ChatGPT is only 3 years old, the rapid development of new generative AI applications for patient use may seem like science fiction. As Bitterman said, “This is so far beyond what I would have predicted 5 years ago.”

Published Online: March 6, 2026. doi:10.1001/jama.2026.1122

Conflict of Interest Disclosures: Dr Bitterman reported serving as an associate editor of JCO Clinical Cancer Informatics, Annals of Oncology, and radiation oncology for HemOnc.org. She also reported receiving consulting fees from Inspire Exercise Medicine LLC and honoraria from Harvard Medical School, Med-IQ, and the National Comprehensive Cancer Network and serving as a scientific advisory board member for Blue Clay Health LLC and Mercurial AI. Dr Liebovitz reported receiving research grants from Children’s Hospital of Philadelphia, the FDA, Merck Sharp & Dohme, the National Institutes of Health, the National Science Foundation, and the University of Chicago. He also reported that he has an ownership or investment interest in CodeAccelerate, Dendritic Health AI, KYRAL Inc, and Optima Integrated Health Inc. Dr Cacciamani reported holding equity in EditorAIPro, of which Pub2Post is a product. Dr Forte reported that his research at Mayo has been funded by Dalio Philanthropies, the Gerstner Family Foundation, the Richard M. Schulze Family Foundation, and Schmidt Sciences and that he is a paid medical advisor for OpenEvidence. No other disclosures were reported.

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In this episode, Sam Ashoo, MD and T.R. Eckler, MD discuss the February 2026 Emergency Medicine Practice article, Emergency Department Diagnosis and Management of Acute Coronary Occlusion

00:00 – Introduction & Welcome

01:21 – Episode Overview: Acute Coronary Occlusion

02:06 – Why This Topic Matters: Statistics & New Guidelines

03:35 – Nomenclature: ACO vs STEMI/NSTEMI

06:15 – Differential Diagnosis for STEMI

07:41 – Pre-Hospital Care & EMS Role

11:37 – Patient History & Presenting Symptoms

12:28 – Physical Examination Findings

14:54 – EKG: The Most Important Test

17:00 – STEMI Definition & Criteria

20:32 – STEMI Equivalents: Scarbosa Criteria

22:40 – Smith Modified Scarbosa Criteria

24:10 – Hyperacute T Waves

25:30 – Posterior STEMI

28:40 – De Winter Sign

29:38 – Non-STEMI EKG Findings

31:30 – AVR ST Elevation

32:47 – Wellens Syndrome

33:54 – Reciprocal ST Segment Changes

36:15 – Inferior MI Patterns

37:54 – Laboratory Testing

39:51 – Imaging: Chest X-Ray & Echocardiography

42:25 – Supplemental Oxygen: What the Evidence Shows

44:50 – Analgesia & Pain Management

46:35 – Pharmacotherapy: Aspirin & Antiplatelet Agents

49:18 – Reperfusion Therapies & Thrombolytics

53:05 – Cardiac Arrest in STEMI Patients

53:55 – Closing Remarks & CME Information

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Reference: . Timing of repeat epinephrine to inform paediatric anaphylaxis observation periods: a retrospective cohort study. Lancet Child & Adolescent Health. July 2025

Dr. Kammeron Brissett

Guest Skeptic: Dr. Kammeron Brissett is a pediatric emergency medicine fellow at Children’s National Hospital in Washington, DC. She completed her pediatrics residency and a chief year at Rainbow Babies and Children’s Hospital in Cleveland, Ohio. Her interests include injury prevention, social determinants of health, and advocacy.

Case: A 7-year-old boy with a peanut allergy presents to the emergency department (ED) after eating a cookie at a birthday party. Shortly afterwards, he developed hives and wheezing. His parents gave him an epinephrine auto-injector to improve his symptoms. In the ED, he feels much better. His vital signs are normal, and his lungs are clear. He has no other gastrointestinal or cardiovascular symptoms. The parents tell you, “Unfortunately, we’ve been through this before. It’s not the first time he has accidentally eaten something that may have had some peanuts in it. Last time, we sat in the ED for a few hours before going home. It’s been a long day. Can we just go home now?”

Background:  Anaphylaxis is a serious, potentially life-threatening systemic allergic reaction with a fast onset. It is a clinical diagnosis that should be considered when:

Early recognition and treatment with intramuscular epinephrine is crucial.

Sometimes, even after initial symptom improvement with IM epinephrine, anaphylaxis symptoms can recur even without exposure to the known trigger. This is called a biphasic reaction and can happen up to 72 hours later.

The SGEM discussed anaphylaxis and biphasic reactions 13 years ago on SGEM#57. The bottom line was that prolonged observation is likely unnecessary in patients whose symptoms resolve with therapy in the ED. Biphasic reactions are rare and can occur anywhere from 10 minutes up to 6 days. We already have problems with boarding and overcrowding. We can’t keep all patients with anaphylaxis for 6 days. So, when can we send them home?

Traditionally, ED observation after anaphylaxis has been around 4 to 6 hours to monitor for biphasic reactions. The Resuscitation Council UK recommends a risk-stratified approach: A patient can be discharged after 2 hours when there’s a good response to a single dose of epinephrine, the symptoms have resolved, the child and family has another epinephrine autoinjector and knows how to use it, and has adequate supervision after discharge. They recommend at least 6 hours of observation if two IM doses of epinephrine were needed or there was a prior biphasic reaction. Finally, they recommend at least 12 hours observation if there was severe respiratory compromise, >2 doses of epinephrine, ongoing allergen absorption, late-night presentation/limited access to care, or difficult access to emergency services.

The National Institute for Care and Health Excellence (NICE) is even a bit more conservative, recommending any child under age of 16 with suspected anaphylaxis be admitted. What about in the US?

In the United States, the 2023 AAAAI/ACAAI Joint Task Force Practice Parameter (JTFPP) emphasizes individualized, risk-based observation and shared decision-making, noting that risk for biphasic reactions is higher with more severe initial reactions and when >1 dose of epinephrine is required. It also highlights that patients with a prompt, complete, and durable response to epinephrine may not always require activation of EMS or prolonged monitoring, underscoring tailored disposition planning.

Reference: . Timing of repeat epinephrine to inform paediatric anaphylaxis observation periods: a retrospective cohort study. Lancet Child & Adolescent Health. July 2025

Authors’ Conclusions: “A 2-h observation period is probably safe for most children who present to an emergency department with an acute allergic reaction requiring epinephrine. A 4-h observation period might be enough for patients with cardiovascular involvement who appear well.”

 Quality Checklist for Observational Study:

Results: They included 5,641 eligible children with a median age of 7.9 years, with slightly more males (56%). 4956 (88%) fulfilled the National Institute of Allergy and Infectious Diseases and Food Allergy and Anaphylaxis Network criteria for anaphylaxis.

In that group, 1.5% met criteria for biphasic anaphylaxis and 10.7% had persistent anaphylaxis.

4.7% received repeat epi after 2 hours from initial dose. 1.9% received repeat epi dose after 4 hours.

Patients with cardiovascular involvement had higher rates of biphasic anaphylaxis.

Among all patients, 5% received a repeat dose of epinephrine after 115 minutes. There were differences in patients with or without respiratory or cardiovascular involvement.

Primary Outcome: In the entire cohort, 4.7% received epi 2 hours after the initial dose, 1.9% received epi after 4 hours, 1.1% received epi after 6 hours, and 0.8% received epi after 8 hours. 

Secondary Outcomes: 

Diagnosis of Anaphylaxis

 We mentioned that anaphylaxis is a clinical diagnosis, but it’s not always clear-cut. In this retrospective review, the authors used ICD-10 codes and chart reviews to determine whether patients experienced anaphylaxis. They included patients who were treated with intramuscular, subcutaneous, or intravenous epinephrine. Potential biases include selection bias, information bias, and misclassification bias.

Not all the patients included in this study actually met criteria for anaphylaxis, which is acknowledged by the authors. Anaphylaxis Practice Guideline update in 2023 states, “treatment with epinephrine or clinical response to epinephrine should also not be used as a surrogate marker to establish a diagnosis of anaphylaxis because there are many cases in which patients receive epinephrine for milder reactions.” Some of these patients were included because authors reported that “the administration of epinephrine might have mitigated reaction progression.”

Appendix Table 3, which examines interrater reliability for agreement on anaphylaxis identification, reports kappa values ranging from 0.68 to 0.76, indicating substantial agreement but not perfect agreement.

Repeat Epinephrine

 The primary outcome for this study was the time from first to last administration of epinephrine. We must be careful and state that this is not the equivalent of a biphasic reaction.

The decision to administer a repeat dose of epinephrine is also not always clear-cut. It is pragmatic. The clinician may have decided to administer another dose of epinephrine despite the patient not meeting the exact definition of anaphylaxis or a biphasic reaction. Epinephrine may have been administered because the child exhibited concerning signs or symptoms.

For example, if a child was being observed in the ED after experiencing anaphylaxis and receiving that first dose of epi started saying that his throat was feeling weird again, we wouldn’t fault the clinician for choosing to give a second dose of epinephrine, but we just wouldn’t know if the child really needed it.

Confounding

 Any observational study is at risk of confounding. One example we can see is if we look at Figure 3, it appears that the pre-emergency administration of epinephrine is a factor that increases the odds of repeat administration of epinephrine.

This is somewhat counterintuitive, as early recognition of anaphylaxis and administration of epinephrine should be beneficial. Instead, this may indicate disease severity. Sicker children received epinephrine in the pre-emergency setting.

We can also see something similar with steroid use in the emergency department associated with an increased odds of repeat epinephrine. I do not routinely give corticosteroids for anaphylaxis, given that the likelihood of benefit is low or uncertain. In this study, it may be more indicative of a patient who had a more severe reaction.

 Risk of Repeat Epinephrine

 The study team a priori defined the observation threshold at which the cumulative incidence of repeat epinephrine dosing increased by < 2% with each 1-hour increase in observation time. It’s not clear where this 2% came from.

The paper reports that this “was deemed clinically acceptable because it represented the optimal balance between prolonged observation with limited benefit and the likelihood of biphasic reaction occurring after discharge.”

Who decided this? Was it the authors? Was there any input from patients and families? Ultimately, individual clinicians and patients/families may have differing risk thresholds.

Bounce Backs for Biphasic Anaphylaxis

 Assuming a patient who is discharged from the ED for anaphylaxis with an epinephrine autoinjector returns after a biphasic reaction. Is that necessarily a failure, or should it reflect negatively on the discharging clinician?

A significant part of our work in the ED is to provide anticipatory guidance and discuss signs and symptoms that would prompt the patient to return to the ED for care. It can be argued that a patient returning to the ED after discharge for a biphasic anaphylactic reaction who self-administered an epinephrine autoinjector is a good thing. This indicates that our anticipatory guidance was effective and well delivered.

Comment on the Authors’ Conclusion Compared to the SGEM’s Conclusion: In general, we agree that most pediatric patients likely do not require prolonged observation in the ED after being treated for anaphylaxis. However, the risk tolerance for a biphasic reaction may vary among patients, families, and clinicians.

Case Resolution: The 7-year-old boy improved rapidly after a single dose of IM epinephrine. During his time in the ED, he has no difficulty breathing or changes in hemodynamics. After discussion with the family, you recognize that they are familiar with signs and symptoms of anaphylaxis and know how to administer IM epinephrine auto-injector. You also confirm that the family has another epinephrine auto-injector at home and send them with a prescription for two new auto-injectors. Afterwards, you send them home.

Clinical Application: There is limited high-quality evidence on observation times for anaphylaxis. Specifically, there is no evidence that any particular observation period is superior, as biphasic reactions may occur up to 72 hours after the initial event. Institutional guidelines may vary. Remember the pillars of evidence-based medicine. Consider your clinical judgement and the patient or family’s values and preferences. Prior to discharge, ensure the patient feels better, that families and patients are aware of the signs and symptoms of anaphylaxis and biphasic reactions, and that they have another epinephrine autoinjector at home.

What Do I Tell the Patient/Family?

Sorry that this happened to your son. It’s great that he seems to be feeling better. It sounds like you have found yourself in this situation before. There’s no set amount of time we must observe him in the emergency department. Let’s briefly go over what symptoms to look out for at home and make sure that you can get another epinephrine autoinjector before you leave the ED.

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"Should we be giving blood transfusions to patients with traumatic cardiac arrest?" EMJ editor Prof. Richard Body and associate editor Dr. Sarah Edwards talk through some original research on the value of blood transfusions in this difficult situation. Next is the new UNCORKED study from the Trainee Emergency Research Network (TERN), with some sobering statistics on the prevalence of emergency care carried out in non-standard treatment places across the UK. Then we move to a world of high-pressure injuries, often caused by industrial spraying equipment, where things on the surface aren't quite as they seem. The last paper returns to the theme of cardiac arrests, examining the predictive value of end-tidal CO2 usage.

Read the highlights: Primary survey:

The EMJ podcast is hosted by:

Prof. Richard Body, EMJ Editor-in-Chief, University of Manchester, UK (@richardbody)

You can subscribe to the EMJ podcast on all podcast platforms to get the latest podcast every month. If you enjoy our podcast, please consider leaving us a review or a comment on the EMJ Podcast Apple (https://apple.co/4bfcMU0) or Spotify (https://spoti.fi/3ufutSL) page.

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