Lake Geneva Fire Department paramedics can now perform focused cardiac scans in the field using handheld ultrasound devices.

More details: https://www.ems1.com/cardiac-care/wis-fire-department-equips-paramedics-with-ultrasound-for-cardiac-arrest-calls

PREHOSPITAL POINT-OF-CARE ULTRASOUND IN CARDIAC ARREST — 2026

From Rhythm Recognition to Real-Time Cardiac Imaging: Handheld Ultrasound Is Moving Into the Paramedic Resuscitation Toolkit

By DrRamonReyesMD ⚕️
EMS Solutions International — 2026

ABSTRACT

Out-of-hospital cardiac arrest (OHCA) remains one of the most time-critical challenges in emergency medical services. Despite major advances in high-quality cardiopulmonary resuscitation (CPR), early defibrillation, airway management, pharmacology, dispatcher-assisted CPR, extracorporeal resuscitation pathways, and post-arrest care, survival remains limited. The 2025 American Heart Association (AHA) guidelines report survival to hospital discharge after EMS-treated OHCA at approximately 10.5% in the United States.

Against this background, prehospital point-of-care ultrasound (POCUS) is emerging as an increasingly important extension of the paramedic physical examination. Compact handheld ultrasound systems can provide focused cardiac and pulmonary imaging at the scene, potentially helping clinicians distinguish true cardiac standstill from residual myocardial activity, characterize selected forms of pulseless electrical activity (PEA), and investigate reversible causes of arrest.

A notable 2026 example highlighted by EMS1 is the implementation of handheld ultrasound by paramedics from the Lake Geneva Fire Department in Wisconsin for cardiac-arrest responses. This development illustrates a broader evolution in advanced EMS: diagnostic imaging, once largely confined to hospitals, is progressively moving to the patient's side — including the roadside, home, ambulance and austere environment.

The technology, however, must be integrated with a fundamental constraint: POCUS must never compromise high-quality CPR or unnecessarily prolong peri-shock or pulse-check pauses.

Keywords: POCUS; cardiac arrest; OHCA; paramedic; EMS; ultrasound; echocardiography; resuscitation; PEA; reversible causes; prehospital medicine.

---

1. THE EMS1 / LAKE GENEVA CASE: WHY IT MATTERS

In 2026, EMS1 reported an important development in American prehospital medicine: Lake Geneva Fire Department paramedics can perform focused cardiac ultrasound examinations in the field using handheld devices during cardiac-arrest calls.

This is more significant than simply putting another diagnostic device aboard an ambulance.

The Lake Geneva Fire Department is a paramedic-level municipal fire/EMS system. Public county documentation describes a mixed career/part-time agency with 23 full-time and 26 part-time personnel and reports 1,663 EMS calls during 2024.

Its own operational history also demonstrates experience managing OHCA. For example, a documented May 2025 arrest resulted in ROSC followed by neurologically intact survival.

The significance of the 2026 POCUS initiative is therefore conceptual:

the ultrasound machine is leaving the imaging department and entering the resuscitation algorithm at the point where physiology is actually failing.

---

2. WHAT IS PREHOSPITAL POCUS?

Point-of-care ultrasound is a focused, goal-directed ultrasound examination performed and interpreted by the treating clinician at the bedside or scene.

It is not synonymous with formal comprehensive echocardiography.

That distinction is essential.

A paramedic performing POCUS during cardiac arrest is generally not attempting to perform a complete cardiology study with formal measurements of chamber dimensions, valvular function, Doppler hemodynamics and detailed ventricular quantification.

Instead, POCUS asks narrow, time-critical questions:

Is the heart moving?

Is there a large pericardial effusion compatible with tamponade physiology?

Is the right ventricle markedly dilated in a clinical context compatible with pulmonary embolism?

Is profound hypovolemia plausible?

Is pneumothorax present?

Is there pulmonary congestion?

Is the electrical rhythm accompanied by meaningful mechanical activity?

This is resuscitative ultrasonography, not conventional elective echocardiography.

---

3. THE PARTICULAR VALUE OF ULTRASOUND DURING CARDIAC ARREST

Traditional ALS assessment gives rescuers several windows into the patient:

• ECG → electrical activity
• pulse assessment → macroscopic circulation
• capnography → ventilation and indirect perfusion information
• blood pressure → circulation when measurable
• clinical examination → probable cause

POCUS adds something fundamentally different:

direct visualization of mechanical cardiac activity.

A monitor may show organized electrical activity while the clinician cannot palpate a pulse.

Traditionally, that is classified as PEA.

But PEA is physiologically heterogeneous.

Ultrasound may demonstrate either:

true PEA: electrical activity with essentially absent mechanical myocardial activity,

or

pseudo-PEA: organized electrical activity associated with visible cardiac contractions but insufficient perfusion to produce a readily palpable pulse.

That distinction may contribute clinically useful information during resuscitation, although it must be interpreted alongside the entire physiologic picture.

---

4. CARDIAC MOTION AND PROGNOSIS

Cardiac activity detected by POCUS is associated with a substantially greater probability of ROSC than complete sonographic cardiac standstill.

One systematic review/meta-analysis involving 1,486 patients with atraumatic, non-shockable cardiac arrest found cardiac activity on POCUS had a pooled sensitivity of approximately 60.3% and specificity of 91.5% for predicting ROSC.

But this creates one of the most important warnings in resuscitative ultrasound:

Cardiac standstill on a single ultrasound examination must not become an isolated reason to terminate resuscitation.

Absence of visible motion is a prognostic observation—not, by itself, a death test.

A later systematic review similarly concluded that POCUS has potential diagnostic and prognostic value during arrest but emphasized important limitations, including heterogeneity, the possibility of self-fulfilling prognostication and interference with CPR.

---

5. POCUS AND THE REVERSIBLE CAUSES OF CARDIAC ARREST

The classical ALS approach remains centered on identifying and correcting reversible causes.

POCUS can complement this process.

Hypovolemia

A markedly underfilled heart may support profound volume depletion in the appropriate clinical setting.

But isolated measurements—particularly inferior vena cava dimensions—should not be interpreted simplistically during cardiac arrest or positive-pressure ventilation.

Cardiac tamponade

POCUS can rapidly demonstrate pericardial fluid and associated cardiac findings.

In the appropriate clinical context, this may radically alter management.

Pulmonary embolism

Severe acute right ventricular strain or dilatation may increase suspicion of massive pulmonary embolism.

But right ventricular dilation is not synonymous with PE, particularly during prolonged cardiac arrest, where ventricular geometry may change.

Tension pneumothorax

Lung ultrasound can support the diagnosis through findings such as absent lung sliding and, when obtainable, a lung point.

Again, during arrest, treatment of an obvious tension pneumothorax should not be delayed merely to obtain an ultrasound image.

The available diagnostic literature supports POCUS as potentially useful for investigating arrest etiology, while also demonstrating that diagnostic accuracy varies substantially depending on the pathology and sonographic sign being assessed.

---

6. THE CRITICAL RULE: ULTRASOUND MUST NOT INTERRUPT CPR

This is arguably the most important operational point.

POCUS can harm a cardiac-arrest patient if clinicians become preoccupied with obtaining the perfect image.

Prehospital evidence has repeatedly identified the potential for ultrasound to prolong interruptions in chest compressions.

Therefore:

CPR drives the ultrasound examination.
The ultrasound examination must never drive CPR.

The probe and imaging window should ideally be prepared while compressions continue.

Image acquisition occurs during an already indicated rhythm/pulse assessment.

The operator obtains the required clip rapidly.

Compressions restart immediately.

Interpretation can then occur from the stored cine loop while CPR continues.

Do not keep the patient's chest motionless while several clinicians stare at the screen debating an image.

---

7. A PRACTICAL PREHOSPITAL CARDIAC-ARREST POCUS WORKFLOW

A mature EMS implementation can integrate ultrasound into the existing ALS cycle rather than create a separate diagnostic event.

During CPR: prepare the device, select the cardiac preset, position the probe and anticipate the best window.

At the scheduled rhythm check: obtain a rapid cardiac cine loop.

Immediately resume compressions.

During active CPR: review the recorded image.

The sonographic question should remain binary or highly focused:

Cardiac activity?

Pericardial effusion?

Gross RV abnormality?

Other immediately actionable pathology?

Then integrate the result with ECG rhythm, ETCO₂, clinical context, arrest circumstances, response to therapy and other physiologic data.

---

8. WHICH CARDIAC WINDOW?

For cardiac arrest, the optimal view is not necessarily the most aesthetically impressive image.

It is the image that answers the clinical question fastest without disrupting resuscitation.

Common approaches include:

Subxiphoid/subcostal view

Historically attractive because the probe can sometimes be positioned without significantly interfering with the compressor.

Parasternal long-axis view

May provide excellent visualization in some patients and may be easier than the subcostal window depending on body habitus.

Apical views

Potentially useful but frequently less practical during active resuscitation.

The correct operational philosophy is therefore:

best obtainable diagnostic window, minimum interruption.

---

9. POCUS DOES NOT REPLACE ETCO₂

This deserves emphasis.

Ultrasound and waveform capnography provide different information.

Capnography remains extraordinarily useful during ALS for monitoring ventilation, helping assess CPR physiology and identifying abrupt ETCO₂ changes potentially associated with ROSC.

POCUS visualizes anatomy and mechanical cardiac activity.

They should therefore be regarded as complementary technologies:

ECG = electricity

POCUS = motion/anatomy

ETCO₂ = ventilation + indirect perfusion information

clinical examination = context

Together they provide a much richer physiologic picture than any single monitor.

---

10. POCUS DOES NOT REPLACE THE PULSE CHECK EITHER

Ultrasound can expose the limitations of manual pulse palpation, particularly in profound low-flow states.

However, the correct response is not to replace every pulse assessment with prolonged cardiac imaging.

The objective is multimodal resuscitation.

The clinician integrates:

ECG + pulse assessment + ETCO₂ + POCUS + blood pressure when available + clinical circumstances.

No isolated parameter should dominate the entire resuscitation.

---

11. BEYOND CARDIAC ARREST: WHY EMS SYSTEMS ARE INTERESTED

Once a prehospital system develops robust ultrasound governance, the potential applications expand considerably.

Focused prehospital ultrasound has been studied in:

shock,
dyspnea,
heart failure,
trauma,
pneumothorax,
hemoperitoneum,
vascular access,
cardiac arrest,
and selected obstetric emergencies.

A systematic review of prehospital critical-care POCUS found that ultrasound was feasible and could alter management in trauma, respiratory emergencies and cardiac arrest, although evidence that it independently improves patient-centered outcomes remained insufficient.

That distinction is scientifically crucial:

Diagnostic capability ≠ proven survival benefit.

---

12. TRAINING IS THE REAL TECHNOLOGY

Purchasing handheld ultrasound units is relatively easy.

Creating competent operators is considerably harder.

A successful EMS POCUS program requires:

initial didactic education;

hands-on image acquisition;

simulation;

supervised clinical examinations;

image archiving;

physician/experienced sonographer QA;

competency assessment;

continuing education;

and periodic review of clinical integration.

Earlier prehospital evidence suggested that brief courses may teach basic image interpretation, while reliable acquisition—particularly advanced acquisition—requires substantially greater supervised experience.

Therefore, the real implementation package is not:

ambulance + ultrasound.

It is:

device + protocol + operator competency + QA + medical oversight + data governance.

---

13. THE DANGER OF “ULTRASOUND VISION”

Every powerful diagnostic technology introduces cognitive bias.

POCUS is no exception.

Clinicians can become anchored to an impressive image and neglect contradictory physiology.

Examples include:

RV dilation → “must be PE.”

Not necessarily.

No cardiac motion → “resuscitation is futile.”

Not necessarily.

Pericardial fluid → “tamponade.”

Not necessarily.

Absent lung sliding → “tension pneumothorax.”

Not necessarily.

POCUS findings must always be interpreted within the pre-test probability, arrest mechanism, clinical examination and complete resuscitation dataset.

---

14. WHAT THE CURRENT GUIDELINES TELL US

The modern evidence-based framework remains centered on excellent fundamentals.

The 2025 AHA Guidelines for CPR and Emergency Cardiovascular Care represent the current major American guideline update.

Similarly, the European Resuscitation Council Guidelines 2025 incorporate the contemporary ILCOR evidence-review framework for resuscitation practice.

The message for POCUS-capable EMS systems is straightforward:

ultrasound is an adjunct to ALS—not a substitute for ALS.

Nothing about a handheld probe makes delayed defibrillation, inadequate compression depth, excessive pauses, poor ventilation strategy or failure to address reversible causes acceptable.

---

15. THE 2026 EMS PARADIGM: THE AMBULANCE AS A MOBILE CRITICAL-CARE PLATFORM

The Lake Geneva development highlighted by EMS1 represents something larger than ultrasound.

Modern advanced EMS is progressively acquiring technologies previously associated primarily with emergency departments and intensive-care units:

12-lead ECG,

waveform capnography,

video laryngoscopy,

mechanical ventilation,

non-invasive ventilation,

advanced hemodynamic monitoring,

blood products in selected systems,

prehospital laboratory testing,

mechanical CPR in selected circumstances,

telemedicine,

and now increasingly handheld ultrasonography.

Lake Geneva itself had previously reported introducing video laryngoscopy and described successful first-attempt airway management during a cluster of cardiac arrests, demonstrating the department's broader movement toward technologically supported advanced prehospital care.

The trajectory is clear.

The ambulance is evolving from a transportation vehicle into a mobile resuscitation and diagnostic environment.

---

16. THE MOST IMPORTANT LIMITATION

There is currently no scientifically defensible basis for saying:

“prehospital ultrasound saves cardiac-arrest patients.”

That statement goes beyond the evidence.

A more accurate 2026 formulation is:

Prehospital POCUS can provide rapid, clinically relevant information during cardiac arrest and may improve diagnostic precision and resuscitation decision-making when performed by appropriately trained clinicians without interrupting high-quality CPR; definitive evidence demonstrating an independent improvement in neurologically intact survival remains limited.

That is the distinction between technological enthusiasm and evidence-based medicine.

---

CONCLUSION

The introduction of handheld cardiac ultrasound for Lake Geneva Fire Department paramedics, highlighted by EMS1 in 2026, is an excellent example of the continuing transformation of prehospital medicine.

POCUS gives paramedics something that generations of rescuers did not possess:

a window into the heart during resuscitation.

For the first time, an EMS clinician standing beside a patient in cardiac arrest can potentially correlate electrical activity with myocardial motion, rapidly search for selected reversible causes and bring anatomical information into the resuscitation decision process before the patient ever reaches an emergency department.

But the hierarchy remains absolute:

High-quality CPR first.
Early defibrillation when indicated.
Minimize interruptions.
Treat reversible causes.
Use ETCO₂ and physiologic monitoring intelligently.
POCUS only when it adds information without compromising those priorities.

The handheld ultrasound probe should therefore not be regarded as another gadget placed in the ambulance.

Used correctly, it represents something more important:

the extension of bedside critical-care imaging to the roadside.

And the Lake Geneva experience reported by EMS1 is another indication that, in 2026, the boundary between the emergency department and advanced prehospital critical care continues to narrow.

By DrRamonReyesMD ⚕️
EMS Solutions International — 2026

Selected scientific sources