Integrating POCUS into CPR: Ultrasound-Guided Decision Pathways (Part 3)

Table of Contents

By Abdolghader Pakniyat (Reviewed by Dr. Sabrina Berdouk )

Educational content only. Follow your local AHA/ERC guidelines and institutional protocols. POCUS is operator-dependent.

By Part 3, the question is no longer whether ultrasound has a role in cardiac arrest.
The real question is simpler and harder:

What should POCUS actually change?

Not every finding deserves an action.
Not every image deserves a pause.
And not every abnormality deserves treatment.

POCUS earns its place in CPR only when it changes the next step without delaying the proven step. Both the 2025 AHA adult ALS guidance and ERC 2025 say the same core thing: intra-arrest POCUS may be used by experienced or skilled operators to diagnose reversible causes, but it must not interrupt or prolong CPR. ERC also makes three guardrails explicit: POCUS may help identify tamponade and tension pneumothorax, RV dilation alone should not diagnose PE, and myocardial contractility should not be the sole reason to stop CPR. (cpr.heart.org)

This post is the action piece of the series:
what to do next when POCUS shows something meaningful during CPR.

The non-negotiable rules

Before any pathway, keep the same discipline from Parts 1 and 2:

CPR is the treatment.
ECG leads shock decisions.
One pause = one primary question.
Acquire during the pause. Interpret during compressions.
If scanning prolongs the pause, stop scanning.

Resuscitation ultrasound protocols are built around that cycle: prepare during compressions, acquire a brief clip during the planned pause, restart compressions immediately, then interpret and act while CPR continues. The 2024 review and the 2025 Advanced Point-of-Care Ultrasound text both emphasize trained operators, role separation, parallel noncardiac scanning during compressions, pre-scanning to identify the best window, recording the clip during the pause, and even using a countdown to limit pause length.

Step 1: Decide whether this should be a scan cycle

Do not scan reflexively.
Scan only if three conditions are true:

A trained sonographer is available
A timekeeper is controlling the pause
The answer could change management now

If not, do not scan. High-quality CPR wins.

Step 2: Use one fixed loop every cycle

During compressions

Choose the one question for the next pause.
Pre-position the probe and identify the window before compressions stop.
Use ongoing compressions for parallel tasks that do not steal pause time, such as DVT scanning, airway confirmation, or abdominal free-fluid assessment when clinically relevant.

During the planned pulse/rhythm check

Record one brief clip.
Do not narrate. Do not chase a better image. Do not answer three questions from one pause.

Immediately after

Back on the chest.

During compressions again

Interpret the clip.
Announce the decision, not the image.

The decision pathways

1) Obstructive pathway

This is the highest-yield use of POCUS in arrest, because these are the findings that can change management immediately.

Tamponade

When to suspect it: PEA or profound shock in the right trauma or medical context.

What POCUS may show: pericardial fluid plus tamponade physiology, especially right-sided chamber collapse. The review is clear that effusion alone is not tamponade; one of its example figures shows pericardial effusion without RV collapse, and tamponade is not diagnosed.

What to do next:
Resume CPR immediately and announce:
“Tamponade likely—prepare pericardiocentesis.”
Emergency pericardiocentesis is indicated when tamponade is suspected or confirmed, and ultrasound can guide the procedure.

What not to do:
Do not spend extra pauses trying to make the picture prettier.
If the physiology and context fit, move to action.

Tension pneumothorax

When to suspect it: obstructive physiology, ventilation difficulty, trauma, severe asthma, or a clinical context that fits.

What POCUS may show: absent lung sliding, underfilled cardiac chambers, plethoric IVC. The 2024 review states that lung pulse rules out pneumothorax at that spot.

What to do next:
Resume CPR immediately.
If the pattern and clinical context strongly support tension PTX, decompress. The review is explicit that immediate thoracostomy or decompression can be a life-saving emergency intervention.

What not to do:
Do not turn the pause into a long bilateral lung survey.

Presumed pulmonary embolism

This is where clinicians get into trouble.

When to suspect it: refractory PEA with a compatible story, risk factors, early right-heart strain pattern, and supportive data when available.

What POCUS may show: RV dilation, underfilled LV, septal flattening or D-shape, sometimes DVT during parallel scanning. The review notes that a normal RV:LV relationship is about 0.6:1, while 1:1 indicates RV dilation. But it also warns that the association between RV dilation and PE can be weak, because RV dilation is common in cardiac arrest, especially when resuscitation is prolonged.

What to do next:
Resume CPR.
Treat PE as presumed, not proven.
If feasible during compressions, add a proximal DVT scan. Some arrest protocols explicitly include femoral/DVT scanning as supportive evidence for PE.

What not to do:
Do not diagnose PE from RV dilation alone.
Do not let isolated RV dilation alone drive thrombolysis.
That is exactly the overcall ERC warns against. (ERC)

2) Hypovolemia / hemorrhage pathway

This is the “empty heart / low volume” branch.

When to suspect it: trauma, ruptured ectopic, GI bleed, massive volume loss, or an “empty” cardiac pattern.

What POCUS may show: underfilled cardiac chambers, low end-diastolic ventricular volume, and a hyperdynamic LV. The resuscitative ultrasound chapter in Advanced Point-of-Care Ultrasound describes hypovolemia in arrest as an underfilled, hyperdynamic left ventricle and warns against over-relying on IVC alone.

What to do next:
Resume CPR.
Shift toward blood / hemorrhage-control logic per your local pathway.
Use FAST or abdominal scanning during compressions when clinically relevant. The chapter also notes that free fluid in the right context can guide treatment decisions such as blood transfusion or surgical intervention.

What not to do:
Do not over-trust the IVC during CPR.
The review states that CPR physiology, ventilation, and venous congestion can distort IVC interpretation.

3) Airway / ventilation pathway

Sometimes the fastest life-saving decision is not cardiac—it is airway or lung.

When to suspect it: oxygenation failure, difficult ventilation, uncertain tube position, unilateral lung findings, asthma/COPD physiology, or possible mainstem intubation.

What POCUS may show: transtracheal confirmation of correct ETT placement, absent sliding with lung pulse suggesting airway/atelectatic pathology rather than PTX, or pleural / pulmonary abnormalities after the airway is secured. The resuscitative ultrasound chapter specifically notes that transtracheal POCUS can confirm ETT placement and can do so simultaneously with compressions.

What to do next:
Fix airway and ventilation first.
If lung findings suggest airway rather than pneumothorax, correct tube position or ventilatory problem instead of rushing to needle decompression.

What not to do:
Do not let a lung image delay correction of an obvious airway problem.

4) Cardiac activity pathway

This pathway does not tell you whether to shock.
It tells you how to focus the resuscitation when ECG is organized or unclear.

Pseudo-PEA

When to suspect it: organized electrical activity on the monitor, no palpable pulse, but visible cardiac contraction on ultrasound.

Why it matters: pseudo-PEA has better odds of ROSC than true standstill. The 2024 review and the resuscitative ultrasound chapter both describe cardiac activity as prognostically meaningful, especially in nonshockable arrest.

What to do next:
Resume CPR.
Announce:
“Contraction present—treat pseudo-PEA physiology.”
Then hunt reversible causes aggressively: obstructive, hypovolemic, airway, metabolic, toxic.

What not to do:
Do not mistake valve flicker, blood swirl, or transmitted motion for meaningful contraction.

Fine VF / occult shockable rhythm

This deserves a separate sentence because it changes treatment immediately.

If the monitor looks like asystole or very low-amplitude electrical activity, but ultrasound during the planned pause clearly shows a fibrillating ventricle, the practical teaching in Point-of-Care Ultrasound, 2e is straightforward: immediate defibrillation is indicated.

What to do next:
Shock if the rhythm is truly shockable.
Then resume CPR immediately.

What not to do:
Do not turn ultrasound into a long rhythm debate.
Defibrillation should not be delayed to collect a better clip.

Cardiac standstill

What it means: very poor prognosis, but not a stand-alone stop rule in current guideline language.

The resuscitative ultrasound chapter notes that, in nontraumatic nonshockable arrest, cardiac activity on POCUS was associated with higher ROSC and survival-to-discharge odds, while standstill was associated with poor outcomes; however, interrater reliability for “standstill” is only moderate.

What to do next:
Resume CPR.
Treat standstill as a poor prognostic sign and integrate it into your full termination-of-resuscitation pathway.

What not to do:
Do not use myocardial contractility on POCUS as the sole reason to terminate CPR. Both AHA and ERC caution against that. (cpr.heart.org)

Optional add-on: Ultrasound-assisted pulse checks

Manual pulse checks are often inaccurate. The resuscitative ultrasound chapter in Advanced Point-of-Care Ultrasound states that B-mode and color Doppler can identify the presence or absence of pulse more rapidly and accurately than manual palpation, and that a visible sonographic pulse may help identify profound shock states such as pseudo-PEA.

But the rule from Part 2 still applies:

Set up during compressions
Interpret only during the planned pulse check
Time-box it
If unclear → hands back on chest

ROSC remains a clinical picture: rhythm, ETCO₂ trend, perfusion signs, and arterial waveform if available. AHA also notes that a sudden ETCO₂ rise may suggest ROSC, but ETCO₂ should not be used in isolation. (cpr.heart.org)