Carbon Monoxide in the Field
Objective: Suspect CO, give high-flow oxygen, and do not trust SpO₂ to clear the exposure.
Why This Is Hard
The whole family has a headache and nausea. Crews call it food poisoning. CDC and ACEP teaching: CO is colorless. Standard two-wavelength pulse oximetry cannot tell COHb from oxyhemoglobin.
- Open windows, stop the generator, get them out.
- High-flow oxygen per protocol regardless of a pretty SpO₂.
- Multiple patients from one structure is CO or other airborne toxin until you have a better story.
Field Rules (Education)
- Clues: winter, generator, furnace, house fire, several patients with headache/nausea/confusion, cherry-red is late and unreliable.
- CDC / ACEP: high-concentration oxygen until COHb can be measured. Hyperbaric therapy is a system/destination decision, not a truck chamber.
- Pulse ox lies. Some services have CO-oximeters — still treat empirically.
- Pregnant patients are a high-priority destination theme because fetal hemoglobin binds CO.
Field Pitfalls
- Trusting SpO₂ 98%.
- Leaving the generator running while you interview.
- Clinic refusal for a pregnant CO exposure.
Practice
60-second drill
Partner: three family members, winter, generator in the garage, SpO₂ 99%. Oxygen and destination.
Related: Smoke inhalation.
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; protocol still wins
- CDC clinical guidance: carbon monoxide poisoning — 100% oxygen; standard pulse ox is not accurate when COHb is present; pregnancy is high-priority
- ACEP CO clinical policy — high-flow oxygen first; hyperbaric is a selected destination question — the policy is written for EDs, not trucks
Education only. Apply learning within your protocols and medical direction. This is not clinical care guidance.
Check Your Understanding
Street decisions from this lesson only. After you check, the key is highlighted. Education practice — not a certification exam.