Updated August 2026: oxygen during defibrillation guidance reviewed.

Clinical answer

For an open or free-flowing oxygen device, move the mask, nasal cannula, or face-held bag-mask away from the chest while the defibrillator is charging—without interrupting CPR or delaying the shock. Keep a closed ventilation circuit connected to an endotracheal tube or supraglottic airway, and direct exhaust away from the chest.

Oxygen during defibrillation creates a practical tension in every shockable cardiac arrest: oxygen delivery and rapid defibrillation are both essential. The question is whether moving the oxygen device reduces fire risk enough to justify an extra action before the shock.

The best current answer is deliberately cautious: the European Resuscitation Council (ERC) 2025 guideline still recommends moving open oxygen-delivery devices at least 1 metre from the chest. The 2025 American Heart Association (AHA) Adult ALS guideline does not give the same device-distance instruction. New experimental evidence published in August 2026 questions how much the 1-metre manoeuvre changes local oxygen concentration, but it does not prove that defibrillation with an oxygen mask in place is risk-free.

What do guidelines say about oxygen during defibrillation?

The ERC 2025 Adult Advanced Life Support guideline gives explicit fire-safety precautions:

• Take off any oxygen mask—including a bag-mask—or nasal cannula before defibrillation and place it at least 1 metre from the patient’s chest.
• Leave a self-inflating bag or ventilator circuit connected to an endotracheal tube or supraglottic airway.
• Direct oxygen exhaust from the ventilation circuit away from the chest.
• Continue compressions during charging and aim for a peri-shock interruption of less than 5 seconds.

The ERC also states that non-invasive ventilation and high-flow nasal oxygen can increase the risk of an oxygen-enriched environment. Although adhesive pads may reduce arcing compared with handheld paddles, the ERC did not remove the oxygen precaution in 2025.

The 2025 AHA Adult ALS guideline emphasizes rapid defibrillation, minimal interruption of CPR, and use of the maximal feasible inspired oxygen concentration during CPR. Its published Adult ALS recommendations do not contain an equivalent instruction to move a mask or cannula 1 metre away.

That difference should not be interpreted as an AHA recommendation to direct free-flowing oxygen across the chest. Earlier AHA guidance and historical fire reports support avoiding defibrillation in an oxygen-enriched atmosphere, particularly when electrical arcing and high-flow oxygen are present.

Why was oxygen traditionally moved away?

Oxygen is not itself flammable, but it supports combustion. A defibrillation fire requires the familiar fire triad:

• Ignition: electrical arcing, particularly with poor paddle-to-skin contact;
• Fuel: hair, clothing, dressings, bedding, or other combustible material;
• Oxidizer: supplemental oxygen concentrated near the patient.

Defibrillation-related fires are rare, but they have occurred. Historical cases often involved manual paddles, inadequate contact, visible sparking, and oxygen flowing near the head or chest. One particularly hazardous configuration is a disconnected oxygen-containing circuit left flowing beside the patient. The conservative separation rule arose from these events.

What did the 2026 manikin study find?

Hoechter and colleagues published a controlled manikin study on 11 August 2026. The investigators tested 20 standardized resuscitation scenarios across 65 experimental runs, varying the oxygen device, airway, ventilation method, room or ambulance environment, and the distance of the oxygen source. Oxygen was measured every 10 seconds at three clinically relevant sites.

• 6,555 oxygen measurements were recorded.
• The median ambient oxygen concentration was 21.6% (IQR 21.3–22.1%).
• 95% of measurements were below 24%.
• The maximum values at conventional pad regions were 24.0% at the right infraclavicular site and 23.5% at the left axillary site.
• Moving the oxygen source more than 1 metre away did not significantly reduce measured oxygen concentration under the tested conditions.

The study therefore raises a reasonable question: does routinely moving standard oxygen equipment 1 metre away meaningfully change the defibrillation environment when modern adhesive pads are used?

The answer may eventually be “not in many situations,” but the present evidence is not sufficient to replace current safety guidance.

What the study did not prove

This distinction is essential. The study measured ambient oxygen concentration—not sparks, ignition, combustion, burns, or clinical outcomes.

• It was a manikin study rather than a real cardiac-arrest study.
• It could not reproduce all patient factors, including body heat, perspiration, anatomy, chest movement, moisture, and unpredictable mask leakage.
• Measurements were limited to predefined locations and did not map the full spatial distribution of oxygen.
• The sensors had an upper measurement limit of 30%.
• The investigators did not generate sparks or test whether a fire occurred.

A poorly fitting reservoir mask produced oxygen concentrations up to 30% around the neck, although the electrode regions remained mainly unaffected. This reinforces a practical point: equipment position, mask fit, leakage direction, and local airflow matter.

The study should make us question the magnitude of the traditional risk—not declare the risk nonexistent.

Do adhesive pads make oxygen during defibrillation safe?

No. Adhesive pads likely reduce the chance of arcing because they provide more consistent skin contact than manual paddles. The ERC 2025 guideline notes this advantage, and the 2026 investigators reported no known cases of defibrillation-related fire involving modern adhesive pads.

However, absence of reported cases is not proof of zero risk. Poor pad adhesion, folds, gaps, moisture, hair, or combustible material may still create an unsafe environment. The defensible statement is:

Modern adhesive pads probably reduce electrical arcing, but they do not justify ignoring oxygen-related fire precautions.

What should the team do at the shock?

Oxygen or airway setup	Action during defibrillation
Face mask or nasal cannula	Move the open device away during charging; ERC specifies at least 1 metre. Do not delay the shock.
Bag-mask held on the face	Move the bag-mask away during charging, then resume ventilation immediately after the shock.
ET tube or supraglottic airway with bag/ventilator	Keep the closed circuit connected and direct exhaust away from the chest.
High-flow nasal oxygen or NIV	Use greater caution and follow current ERC and local equipment guidance; the 2026 study does not prove universal safety.

A practical sequence for oxygen during defibrillation

1. Continue chest compressions while the defibrillator charges.
2. During charging, move any open or free-flowing mask, cannula, or face-held bag-mask away from the chest.
3. Keep a closed advanced-airway circuit connected and point exhaust away from the chest.
4. Confirm that everyone is clear.
5. Deliver the shock immediately, aiming for a peri-shock pause of less than 5 seconds.
6. Resume compressions immediately, followed by prompt continuation of oxygenation and ventilation.

There should be no prolonged pause while someone measures exactly 1 metre. The fire-safety action should occur during ongoing CPR and defibrillator charging, not become a new pre-shock delay.

Bottom line

• ERC 2025: move open oxygen masks, nasal cannulae, and face-held bag-masks at least 1 metre from the chest before the shock.
• Advanced airway: keep the self-inflating bag or ventilator circuit connected to the ET tube or supraglottic airway, with exhaust directed away.
• AHA 2025: emphasizes rapid defibrillation, minimal interruption, and maximal feasible inspired oxygen during CPR, but does not give the same 1-metre instruction in its Adult ALS recommendations.
• Emerging evidence: the 2026 manikin study found little oxygen enrichment at standard pad sites and no reduction after moving the source more than 1 metre, but it did not test actual fires.
• Bedside priority: move open oxygen during charging without delaying defibrillation; ensure excellent pad contact and an extremely short peri-shock pause.

Continue learning

• 2025 AHA CPR Guidelines: Key Updates and Changes
• Advanced Strategies for Managing VF and pVT in the ED

References

1. Soar J, Böttiger BW, Carli P, et al. European Resuscitation Council Guidelines 2025: Adult Advanced Life Support. Resuscitation. 2025;215:110769.
2. Wigginton JG, Agarwal S, Bartos JA, et al. Part 9: Adult Advanced Life Support: 2025 American Heart Association Guidelines for Cardiopulmonary Resuscitation and Emergency Cardiovascular Care. Circulation. 2025;152(suppl 2):S538–S577.
3. Hoechter DJ, Pfeiffer F, Storz M, et al. Ambient oxygen enrichment during cardiopulmonary resuscitation: an overestimated risk? Insights from a manikin study. Scandinavian Journal of Trauma, Resuscitation and Emergency Medicine. 2026;34:133.
4. Link MS, Atkins DL, Passman RS, et al. Part 6: Electrical Therapies: 2010 American Heart Association Guidelines for Cardiopulmonary Resuscitation and Emergency Cardiovascular Care. Circulation. 2010;122(suppl 3):S706–S719.
5. Ward ME. Risk of fires when using defibrillators in an oxygen-enriched atmosphere. Resuscitation. 1996;31(2):173.