Oxygen Titration

Why this matters

High-flow oxygen became a habit. It is still the right start for a low sat, for suspected carbon monoxide, and for an airway crisis. It is not the treatment for every patient. Too much oxygen can harm some patients. A non-rebreather on a talking patient with chronic obstructive pulmonary disease (COPD) who is already at their usual sat is not thorough care.

Look at the patient, the sat trend, and the disease. Then pick a device and a target that match your protocol. Oxygen saturation (sat) is the number on the probe. Do not treat a bad waveform as a real number.

Clinical sequence

1. If they are blue, severely short of breath, in shock, or the airway is threatened, start oxygen now. Do not wait for a perfect number.
2. Patients with COPD who retain carbon dioxide still get oxygen when they need it. Do not withhold oxygen because of the old hypoxic-drive myth. Titrate to the sat in your protocol. Do not leave them short of oxygen on purpose.
3. For stroke, acute coronary syndrome (a heart-attack picture), and after return of spontaneous circulation, avoid both a low sat and extra oxygen once you can measure. The targets are not the same.
4. Say the device and the target out loud. Check again after every move. Write the starting sat, the device, the flow, and what changed.

Teaching points

• After cardiac arrest. Keep a high oxygen fraction until the sat can be measured reliably. Then aim for about 90–98%. See the return-of-circulation lesson.
• Acute coronary syndrome. Give oxygen if the sat is under 90%. Routine oxygen when the sat is 90% or higher has no benefit.
• Stroke. If the patient is hypoxic, keep the sat above 94%. Do not put a default non-rebreather on a patient who is already saturating well.
• Acute asthma (Global Initiative for Asthma, 2026). Do not start oxygen unless the sat is low, about under 92%. If you give oxygen, do not run them to 100%. An upper teaching target is about 95% in adults and older children. Your protocol owns the number. A deteriorating patient with a silent chest still gets oxygen now.
• Severe traumatic brain injury. Treat a sat under 90% immediately. Suspected severe traumatic brain injury should get continuous supplemental oxygen. Do not copy the heart-attack rule, “only if under 90%,” onto a head injury.
• COPD, once they are improving. A common teaching band is about 88–92%. That number is an example your protocol owns, not an order from this page. Never withhold oxygen from worsening hypoxia to chase that band.
• Match the device to the problem. Use a nasal cannula for a mild need. Use a non-rebreather or a bag when they are truly hypoxic or failing. Continuous positive airway pressure is a different tool. See that lesson.

In practice

• The sat is wrong on cold fingers, in shock, on a dirty finger, and when the patient is moving. If the waveform is poor, treat the patient. Pulse oximetry can also read too high in a hypoxic patient with dark skin, which that same asthma guideline flags. Treat the patient, not a falsely reassuring number.
• Do not copy the post-arrest 90–98% range onto a talking patient with chest pain, stroke, or asthma. Do not copy the stroke target, above 94% if hypoxic, onto chest pain. Do not copy the chest-pain rule, only if under 90%, onto suspected severe traumatic brain injury or onto a talking asthmatic.

Common errors

• Putting a non-rebreather on every chest-pain patient with a sat of 98% on room air.
• Trusting a good sat on a dark-skinned patient who looks hypoxic, when the waveform or the work of breathing says otherwise.
• Withholding oxygen from a hypoxic COPD patient because of the hypoxic-drive myth.
• Never looking at the probe when the number does not match the patient.

Practice

Related: ROSC, CPAP, TBI, Stroke.

Sources & Further Study

Named guidelines for further study. They are not clinical orders and do not replace your protocol or medical direction.

• NASEMSO National Model EMS Clinical Guidelines (2022) — U.S. EMS model language; follow your protocol
• AHA 2025 Part 11: Post–Cardiac Arrest Care — about 90–98% SpO₂ once measured
• 2025 ACC/AHA/ACEP/NAEMSP ACS Guideline — O₂ if SpO₂ <90%; routine O₂ not recommended if ≥90%
• 2026 AHA/ASA Acute Ischemic Stroke Guideline — if hypoxic, maintain SpO₂ >94%; not a default NRB when already saturating well
• BTF Prehospital TBI Guideline, 3rd Edition (2023) — correct SpO₂ <90% immediately; continuous O₂ for suspected severe TBI
• GINA 2026 Strategy Report — acute asthma: oxygen not recommended unless sat is low (about <92%); if given, upper target about 95% in adults and older children. Pulse oximetry may overestimate saturation in hypoxemic patients with dark skin. Protocol still owns the number.
• Treat hypoxemia. Do not apply one saturation band to every disease. Follow your oxygen protocol.