Carbon Monoxide in the Field
Objective: Suspect carbon monoxide. Give high-flow oxygen. Do not use a normal pulse oximeter reading to clear the exposure, and do not withhold oxygen to chase that number.
Why this matters
A whole family with headache and nausea can look like food poisoning. Carbon monoxide has no color and no smell. A standard pulse oximeter reads the sat. It cannot tell carbon monoxide on hemoglobin, the oxygen-carrying part of the red blood cell, from oxygen. Do not use a normal sat to clear the exposure. Give high-flow oxygen. Do not withhold oxygen to chase a number.
- Get people out first. Open windows and turn off the generator.
- Give high-flow oxygen per protocol even when the sat looks normal.
- Several sick people from one building is carbon monoxide, or another shared airborne toxin, until a better story explains it.
Clinical sequence
- Get them into fresh air. Open windows and stop the source. Do not interview next to a running engine in a closed garage.
- Give high-flow oxygen per protocol even if the sat looks fine. Do not turn the oxygen down to chase that number.
- Treat several patients from one house as a shared exposure until you have a better explanation.
- Go to a hospital that can measure carboxyhemoglobin, the carbon monoxide level in the blood. Pregnancy makes that destination more urgent.
Teaching points
- Clues. Winter, a generator, a furnace, a house fire, or several people with headache, nausea, or confusion. Cherry-red skin is late and unreliable. Do not wait for it.
- Oxygen comes first. Give a high concentration until the carbon monoxide level can be measured. Hyperbaric treatment is oxygen in a pressure chamber. That is a hospital decision. The ambulance is not that chamber.
- The pulse oximeter can look normal. Some services have a carbon monoxide oximeter. Still treat the story. Do not clear the exposure with one number.
- Pregnancy. The baby’s blood holds on to carbon monoxide. Treat a pregnant patient as a high-priority transport. Do not accept a refusal after this exposure.
Common errors
- Using a sat of 98% to clear the exposure.
- Leaving the generator running while you take a history.
- Accepting a refusal for a pregnant patient after carbon monoxide exposure.
Practice
One-minute check
Three family members, winter, a generator in the garage, and a pulse oximeter reading of 99%. Name the oxygen plan and the kind of hospital you want.
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; your protocol still decides care
- 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 emergency departments, not ambulances
Education only. Apply learning within your protocols and medical direction. This is not clinical care guidance.
Check Your Understanding
Questions drawn only from this lesson. After you check, the key is highlighted. Education practice — not a certification exam.