A patient has been exposed to carbon monoxide during a house fire. An ABG result shows a normal PaO2. How should the patient's PaO2 value be interpreted?

a. The PaO2 is being falsely elevated by the carbon monoxide.
b. The PaO2 is being falsely decreased by the carbon monoxide.
c. The PaO2 is accurate.
d. The PaO2 is a false measurement because the presence of carbon monoxide makes the analyzer unable to determine the PaO2.

C
The patient's plasma PaO2 value may be normal or high. This can mislead the respiratory therapist because the patient's total oxygen value (CaO2) is low. Remember that carbon monoxide will prevent hemoglobin from carrying oxygen.