Continuous-Flow
Oxygen During Cardiac Arrest and the Search for Better Ventilation
During CPR
The resuscitation is going well.
Compressions are deep and consistent. The defibrillator is ready.
Vascular access is established. Medications are being timed. Someone is
managing the airway.
Then comes a task that looks simple but is surprisingly difficult to
perform consistently during a chaotic arrest:
ventilation.
How often is the bag actually being squeezed?
How much volume is being delivered?
Is the mask sealed?
Are compressions being interrupted?
Is the team hyperventilating?
Is oxygen entering the lungs at all?
And what if oxygen could be delivered continuously without requiring
a rescuer to squeeze the bag for every breath?
That is the idea behind continuous-flow insufflation of oxygen, or
CFIO.
A 2026 multicenter observational study brought renewed attention to
this strategy by comparing CFIO with bag-valve-mask ventilation during
adult out-of-hospital cardiac arrest.
But the finding is not a victory for CFIO.
It is a warning against assuming that a simpler-looking oxygen
strategy automatically produces better outcomes.
LSE Bottom Line: During cardiac arrest, oxygen
delivery, ventilation and high-quality compressions must work together.
A 2026 observational study found CFIO was associated with lower
odds of favorable neurologic outcome than BVM ventilation. That does not
prove CFIO caused worse outcomes, but it absolutely does not support
replacing guideline-based ventilation with CFIO on the basis of current
evidence.
What the 2026 Study Found
The new study examined neurologic outcomes after OHCA in patients
managed with continuous-flow insufflation of oxygen compared with
bag-valve-mask ventilation.
The headline finding matters: CFIO was associated with significantly
lower odds of favorable neurologic outcome at 30 days compared with
BVM.
Because this was observational research, the result cannot establish
that CFIO itself caused worse neurologic outcomes. Patient selection,
EMS-system practices, arrest characteristics and other confounders may
influence the association.
Still, the result pushes against a tempting assumption that
continuous oxygen flow is necessarily equivalent or superior to active
ventilation.
Oxygenation
and Ventilation Are Not the Same Thing
Oxygenation describes getting oxygen into blood. Ventilation
describes moving gas in and out of the lungs, including elimination of
carbon dioxide.
An oxygen source can deliver a high inspired oxygen concentration
without guaranteeing adequate alveolar ventilation.
During cardiac arrest, chest compressions and recoil can generate
some gas movement, but that does not mean passive oxygen delivery will
reliably provide the ventilation required for every patient.
This distinction is fundamental to understanding CFIO.
What Current AHA Guidance
Says
The 2025 AHA adult BLS guideline continues to support active
ventilation during adult cardiac arrest. Without an advanced airway, 30
compressions followed by two breaths remains a reasonable strategy.
Health care professionals may also consider continuous compressions with
asynchronous breaths in adults without an advanced airway.
When ventilating, the guideline emphasizes enough tidal volume to
produce visible chest rise while avoiding both hypoventilation and
hyperventilation.
For bag-mask ventilation, a two-person technique is specifically
supported when personnel are available: one rescuer uses two hands to
open the airway and maintain the mask seal while the second squeezes the
bag.
That recommendation tells us something important. BVM ventilation is
not merely squeezing a bag. It is a team procedure.
After an Advanced Airway
Once an advanced airway is established, the 2025 AHA ALS guideline
states that one breath every six seconds, approximately ten breaths per
minute, may be reasonable while continuous chest compressions
continue.
Continuous waveform capnography is recommended for confirming and
monitoring endotracheal-tube placement.
The airway strategy should therefore be integrated with CPR rather
than becoming a competing procedure.
Maximal Oxygen During CPR
During active adult cardiac arrest, the AHA states that when
supplemental oxygen is available, using the maximal feasible inspired
oxygen concentration may be reasonable.
That is different from saying more ventilation is better.
Inspired oxygen concentration and minute ventilation are separate
variables.
A team can use high-concentration oxygen and still harm the
resuscitation by ventilating too rapidly or with excessive volume.
Why Hyperventilation Is
Dangerous
Excessive ventilation can increase intrathoracic pressure, interfere
with venous return and reduce cardiac output generated during CPR. It
can also contribute to gastric inflation, regurgitation and
aspiration.
This is one reason resuscitation teams need deliberate ventilation
discipline.
A provider under stress can easily squeeze a bag much faster than
intended.
The goal is not maximal ventilation.
The goal is appropriate ventilation.
Hypoventilation Is Not
Harmless Either
The opposite error also matters.
Too little ventilation or insufficient tidal volume can impair gas
exchange. AHA guidance explicitly cautions against both hypo- and
hyperventilation.
That balance makes the CFIO question clinically interesting. A
technique that reduces manual overventilation could theoretically help,
but only if it still provides adequate ventilation for the patient.
That adequacy cannot simply be assumed from oxygen flow.
Visible Chest Rise
For manual ventilation during adult cardiac arrest, AHA guidance uses
a practical bedside target: provide enough tidal volume to produce
visible chest rise.
That is intentionally simple because exact tidal-volume measurement
is rarely available during prehospital resuscitation.
Visible chest rise is imperfect, but it gives the team immediate
feedback that gas is actually entering the lungs.
A continuous-flow system needs its own reliable way of assuring
adequate gas exchange.
Mask Seal Still Matters
Whether oxygen is supplied by a bag or another system, upper-airway
patency and interface performance matter.
A poorly positioned head, obstructed airway or inadequate mask seal
can defeat the strategy.
Two-handed mask seal with jaw opening is one reason two-person BVM
ventilation can outperform a one-handed technique.
Airway positioning remains an intervention.
Chest Compressions Are the
Priority
Ventilation must coexist with high-quality compressions.
AHA BLS guidance identifies a chest-compression fraction of at least
60% as a minimum target and notes that high-performance teams may exceed
80%.
Airway interventions that repeatedly interrupt compressions can
therefore undermine the resuscitation.
The ideal ventilation strategy should support gas exchange without
sacrificing compression quality.
Passive Gas Movement During
CPR
Chest compression and recoil can move small volumes of gas. This
physiologic concept helped drive interest in passive oxygen
strategies.
But passive movement is influenced by airway resistance, chest
mechanics, compression quality and other patient factors.
The existence of airflow does not prove adequate ventilation.
Clinical outcomes, not theoretical elegance, must determine whether a
strategy belongs in routine care.
Why CFIO Is Operationally
Attractive
CFIO can appear operationally appealing because it may reduce the
need for repetitive manual bagging and potentially free a rescuer for
other tasks.
In a resource-limited resuscitation, that is an understandable
attraction.
But reducing workload is clinically valuable only if patient care
remains equivalent or improves.
The 2026 observational result means EMS systems should not equate
operational simplicity with better neurologic outcome.
Could CFIO Reduce
Compression Interruptions?
Potentially, depending on the device and protocol.
But modern BVM ventilation can also be organized around high
compression fraction, particularly with trained teams and asynchronous
ventilation after an advanced airway.
The relevant comparison is not idealized CFIO against poorly
performed BVM.
It is well-executed CFIO against well-executed guideline-based
ventilation.
The Two-Person BVM Technique
AHA specifically describes the advantage of having one rescuer use
two hands to maintain the airway and mask seal while another squeezes
the bag.
This is a useful training point because many poor BVM experiences are
actually poor mask-seal experiences.
If the team cannot ventilate effectively, the first response should
not automatically be to squeeze harder.
Improve positioning, airway opening, adjuncts, seal and
technique.
Capnography During
Resuscitation
End-tidal carbon dioxide can provide valuable information during
CPR.
AHA guidance notes that physiologic parameters such as ETCO2 may be
used when feasible to monitor and optimize CPR quality, and an abrupt
increase in ETCO2 may help identify ROSC.
ETCO2 is influenced by ventilation, pulmonary blood flow, CPR
quality, medications and arrest physiology.
It should be interpreted as part of the resuscitation, not as a
single magic number.
Capnography and Ventilation
Once an advanced airway is established, waveform capnography gives
the team continuous information about exhaled carbon dioxide and tube
placement.
It can also reveal obvious ventilation-rate problems.
A resuscitation team should be able to look at the waveform and
recognize whether breaths are being delivered far more frequently than
intended.
Technology works best when the team actually uses the feedback it
provides.
The Airway Ladder
Cardiac-arrest airway care should not become an intubation race.
AHA guidance allows either bag-mask ventilation or an advanced-airway
strategy depending on the situation and professional skill set.
Supraglottic airways and endotracheal tubes both have roles depending on
system training and performance.
The best airway is the one that supports oxygenation and ventilation
while protecting CPR quality and minimizing complications.
Intubation Can Cost
Compressions
Advanced-airway placement can interrupt compressions, create
malposition risk and lead to hyperventilation.
That is why airway skill and quality improvement matter.
If an intubation attempt repeatedly stops compressions, the
procedural cost may exceed the benefit.
Airway management should fit the resuscitation rather than forcing
the resuscitation to fit the airway procedure.
Ventilation in Asphyxial
Arrest
Not every cardiac arrest begins with the same physiology.
A primary sudden cardiac arrest may initially have different oxygen
reserves from an arrest caused by drowning, severe respiratory failure
or prolonged hypoxia.
AHA special-circumstances guidance emphasizes prompt ventilation in
drowning-related arrest.
This makes universal claims about passive oxygen strategies
especially problematic.
Etiology matters.
Opioid and Respiratory
Arrest Context
Patients whose deterioration begins with respiratory failure create
another reason to distinguish oxygen delivery from ventilation.
If the primary problem is inadequate ventilation, simply increasing
oxygen concentration does not necessarily correct carbon-dioxide
accumulation or provide adequate tidal ventilation.
The airway strategy must match the pathophysiology.
Refractory Arrest
As a resuscitation continues, airway mechanics, pulmonary edema,
aspiration and other factors can change.
A strategy that seemed adequate early may become inadequate
later.
Repeated assessment is therefore essential.
Resuscitation is dynamic, and ventilation should be treated the same
way.
ROSC Changes the Oxygen
Strategy
Return of spontaneous circulation creates a major transition.
During CPR, maximal feasible inspired oxygen concentration may be
reasonable.
After ROSC, the AHA recommends 100% inspired oxygen until oxygen
saturation or arterial oxygen can be reliably measured.
Once reliable measurement is available, the goal changes.
After ROSC, Titrate
The 2025 AHA post-cardiac-arrest guideline recommends avoiding both
hypoxemia and hyperoxemia after ROSC.
Once reliable oxygen measurement is available, titrating FiO2 to an
SpO2 target of 90% to 98% is reasonable. The corresponding PaO2 range
cited by the guideline is 60 to 105 mm Hg.
This is a critical distinction for EMS education.
The oxygen strategy during pulseless CPR is not identical to the
oxygen strategy after circulation returns.
Ventilation After ROSC
For comatose adults after ROSC, the AHA recommends maintaining PaCO2
in a normal physiologic range, generally 35 to 45 mm Hg.
That reinforces the same principle: oxygen and ventilation are
separate variables.
Post-arrest care requires control of both.
Three Phases of Oxygen
Management
A useful teaching model divides the arrest into three phases.
Active cardiac arrest: prioritize high-quality CPR,
defibrillation when indicated, adequate oxygenation and ventilation, and
avoid unnecessary interruptions.
Immediate ROSC before reliable measurement: use 100%
inspired oxygen while rapidly establishing reliable oxygen
assessment.
Post-ROSC with reliable measurement: titrate oxygen
to avoid both hypoxemia and hyperoxemia and manage ventilation
deliberately.
This phase-based model is easier to teach than the vague instruction
to give oxygen.
What the 2026 Study Does Not
Prove
It does not prove that CFIO directly causes poor neurologic
outcomes.
It does not prove that every CFIO device or protocol performs
identically.
It does not prove that BVM is always performed well.
It does not answer every subgroup question.
And it does not establish that continuous-flow oxygen has no future
role.
It does, however, make it inappropriate to claim that CFIO has
demonstrated superiority over BVM for neurologically favorable
survival.
Association Is Not Causation
Observational studies compare what happened in real clinical systems
rather than randomly assigning every intervention.
That makes them valuable, but treatment groups may differ in ways
statistical adjustment cannot completely eliminate.
Perhaps certain patients were more likely to receive one strategy.
Perhaps system workflows differed. Perhaps unmeasured factors influenced
outcomes.
The association should therefore trigger further investigation, not
causal certainty.
Why Randomized Trials Matter
A randomized clinical trial can reduce many selection biases by
assigning interventions prospectively.
For CFIO, a sufficiently powered clinical trial would ideally measure
neurologically favorable survival and important safety outcomes.
It should also track compression fraction, ventilation quality,
airway complications and transitions to advanced airway management.
Until stronger evidence arrives, established guideline-based
ventilation remains the safer educational anchor.
High-Performance CPR Is a
Team Skill
Ventilation problems are often workflow problems.
Who owns the airway?
Who counts the ventilation rate?
Who watches the seal?
Who monitors ETCO2?
Who notices that the compressor is being interrupted?
High-performance teams assign these responsibilities rather than
hoping someone catches the problem.
Metronomes and Ventilation
Timing
Teams can use simple cognitive aids to avoid ventilation-rate
drift.
The exact tool is less important than disciplined execution.
After an advanced airway, one breath approximately every six seconds
is easy to say and surprisingly easy to exceed during a stressful
arrest.
Training should make the intended cadence familiar.
Don’t Chase the Bag
When chest rise is poor, repeatedly squeezing harder is often the
wrong response.
Check airway position.
Use appropriate adjuncts.
Improve mask seal.
Use two hands on the mask when staffing permits.
Assess obstruction.
Consider the next airway strategy when indicated.
Poor ventilation is a diagnostic problem before it becomes a force
problem.
Mechanical CPR Does
Not Solve Ventilation
Mechanical compression devices can create an impression that the
resuscitation has become automated.
It has not.
AHA guidance does not recommend routine mechanical CPR for all adult
arrests.
Whether compressions are manual or mechanical, airway patency,
ventilation rate, tidal volume and oxygen strategy still require active
management.
Quality Improvement
Questions
After an OHCA, review more than whether an airway was placed.
What was the initial ventilation strategy?
Was two-person BVM used?
Were breaths visibly effective?
Was the rate appropriate?
How long did advanced-airway placement take?
Were compressions interrupted?
Was waveform capnography used?
Was hyperventilation evident?
What happened to oxygen after ROSC?
Those questions turn airway management into measurable system
performance.
Train the Transition Points
Many errors occur when the strategy changes.
Thirty-to-two CPR becomes continuous compressions with asynchronous
breaths after an advanced airway.
Pulseless arrest becomes ROSC.
Maximal oxygen becomes titrated oxygen once measurement is
reliable.
Simulation should deliberately test these transitions.
A team that knows each individual guideline can still fail if nobody
recognizes that the patient has entered a different phase.
A Better Research Question
Instead of asking whether CFIO is easier than BVM, ask whether it
produces equal or better neurologically favorable survival without
sacrificing ventilation, compression quality or safety.
Operational convenience should be a secondary outcome.
The primary endpoint should remain the patient.
What Changed From Previous
Teaching?
The biggest change is not that guidelines suddenly endorse CFIO. They
do not.
The 2026 observational evidence adds caution by reporting lower odds
of favorable 30-day neurologic outcome with CFIO compared with BVM.
Meanwhile, the current AHA framework continues to emphasize active
ventilation, visible chest rise, avoidance of hypo- and
hyperventilation, high-quality compressions and appropriate
advanced-airway management.
So the practical change is in our confidence: CFIO should be viewed
as an investigational or system-specific strategy requiring stronger
evidence, not an obvious shortcut to better resuscitation.
Final Takeaway
Cardiac-arrest ventilation is easy to underestimate because the
equipment looks familiar.
But the physiology is complex.
Continuous oxygen flow is not synonymous with adequate ventilation.
Bag-mask ventilation is not automatically effective simply because the
bag moves. Advanced airway placement is not automatically beneficial if
it destroys compression fraction.
The best resuscitation system measures what matters and trains the
team to deliver it consistently.
The goal is not to move oxygen through equipment. The goal is
to move enough gas through the patient while preserving the circulation
CPR is trying to create.
Instructor Lab: The Ventilation Drift Drill
Start a standard adult cardiac-arrest simulation with two-person BVM
ventilation. Do not tell the airway clinician that ventilation rate is
being measured.
As stress rises, observe what happens.
Many clinicians accelerate.
Then repeat the scenario with an advanced airway and continuous
compressions. Ask the team to deliver one breath every six seconds while
simultaneously managing rhythm analysis, medications and compressor
changes.
The objective is not embarrassment. It is awareness.
Drill One: Bad Seal
Create poor chest rise despite appropriate bag compression. The team
should troubleshoot position and mask seal rather than simply squeezing
harder.
Drill Two: Hyperventilation
Have an instructor quietly increase the ventilation rate. The team
leader should identify and correct it.
Drill Three: ROSC
Create ROSC while oxygen remains at maximal concentration. Once
reliable saturation is obtained, the team should recognize the
transition to post-arrest oxygen titration.
Drill Four: Capnography
Change
Introduce an abrupt ETCO2 increase during compressions. The team
should recognize that this can suggest ROSC while confirming clinically
at the appropriate rhythm-check interval.
A Cardiac-Arrest
Ventilation Checklist
Before advanced airway placement, use a deliberate BVM technique,
open the airway, use appropriate adjuncts and look for visible chest
rise.
When staffing allows, use two rescuers for BVM: two hands maintaining
airway position and mask seal, with another clinician squeezing the
bag.
Avoid excessive rate and excessive volume.
Protect chest-compression fraction.
If an advanced airway is placed, confirm an endotracheal tube with
continuous waveform capnography and transition to the
guideline-appropriate asynchronous ventilation cadence.
After ROSC, recognize that oxygen management changes. Use 100% oxygen
until reliable measurement is available, then titrate to avoid both
hypoxemia and hyperoxemia.
QI
Deep Dive: Measure Ventilation as a Resuscitation Process
Ventilation quality should be audited with the same seriousness as
compression quality. Review rate, effectiveness, airway technique,
capnography, compression interruptions and the transition after
advanced-airway placement. When monitor downloads and airway
documentation are available, align the timelines.
A case can have excellent compression depth and rate while
ventilation remains uncontrolled. Conversely, a technically excellent
airway procedure can create a prolonged pause in compressions. Neither
metric should be reviewed in isolation.
The most useful QI process asks what happened to the patient while
the intervention was performed. That approach prevents procedural
success from becoming a substitute for resuscitation success.
SEO FAQ
What is
continuous-flow insufflation of oxygen?
CFIO is an airway strategy that supplies a continuous flow of oxygen
through an interface rather than relying exclusively on intermittent
manual bag ventilation.
Is
CFIO recommended instead of BVM during adult cardiac arrest?
Current AHA adult cardiac-arrest guidance continues to support
bag-mask ventilation and advanced-airway strategies. The 2026
observational study reviewed here does not establish CFIO as
superior.
What did the 2026 CFIO study
find?
CFIO use during OHCA was associated with significantly lower odds of
favorable neurologic outcome at 30 days compared with BVM
ventilation.
Does that prove CFIO is
harmful?
No. The study was observational, so it cannot establish
causation.
How
fast should adults with an advanced airway be ventilated during
CPR?
Current AHA ALS guidance states that one breath every six seconds,
approximately ten breaths per minute, may be reasonable while continuous
compressions are performed.
How much should I squeeze the
BVM?
Current AHA BLS guidance recommends enough tidal volume to produce
visible chest rise while avoiding both excessive and inadequate
ventilation.
Should 100% oxygen be used
during CPR?
The AHA states that maximal feasible inspired oxygen concentration
may be reasonable during adult CPR when supplemental oxygen is
available.
What happens to oxygen after
ROSC?
Use 100% inspired oxygen until SpO2 or PaO2 can be measured reliably.
Once reliable measurement is available, the AHA considers an SpO2 target
of 90% to 98% reasonable.
Is ETCO2 useful during CPR?
Yes. ETCO2 can contribute to physiologic monitoring during CPR, and
an abrupt rise can help identify possible ROSC, but it must be
interpreted in clinical context.
Related Training and Reading
- AHA BLS Training
- AHA ACLS Training
- Prehospital RSI Safety: Successful Tube or Safe Intubation?
- Explore Life Saving Education Courses
Cardiac
Arrest Training Has to Go Beyond the Algorithm
Knowing the algorithm is essential.
Executing high-quality compressions, ventilation, airway management,
defibrillation and post-ROSC transitions as one coordinated team is what
turns knowledge into performance.
Explore Life Saving Education BLS, ACLS and EMS education or
contact us about customized resuscitation training.
References
- Segond N, et al. Neurological outcome of out-of-hospital cardiac arrest patients ventilated with continuous flow insufflation of oxygen: a multicenter observational study. Resuscitation. 2026;225:111113. PMID 42069041.
- American Heart Association. 2025 Guidelines for CPR and ECC, Part 7: Adult Basic Life Support.
- American Heart Association. 2025 Guidelines for CPR and ECC, Part 9: Adult Advanced Life Support.
- American Heart Association. 2025 Guidelines for CPR and ECC, Part 11: Post-Cardiac Arrest Care.
- International Liaison Committee on Resuscitation. 2026 Consensus on
Science with Treatment Recommendations.
Evidence Scope Note
This article is educational and does not replace AHA guidelines,
local EMS protocols, medical direction or device-specific instructions.
The 2026 CFIO outcome study was observational. Association should not be
interpreted as proof that CFIO caused worse outcomes. EMS agencies
considering nonstandard ventilation strategies should evaluate
applicable evidence, protocols, medical oversight, device
characteristics and quality data.
