Which statement correctly describes ETCO2 monitoring in airway management?

• A. It is the best method to detect tube placement into the trachea and the quality of CPR chest compressions
• B. It replaces pulse oximetry
• C. It measures arterial blood gas
• D. It predicts anesthetic depth

Answer: (A)

End-tidal CO2 monitoring uses a capnograph to measure CO2 at the end of expiration, providing a real-time waveform and numeric value that reflect ventilation and perfusion. This is how you confirm airway placement: a tracheal tube should produce a consistent CO2 waveform because CO2 is carried to the lungs and exhaled; absence or a blunted trace strongly suggests esophageal intubation or a misplaced airway. In CPR, the ETCO2 reading tracks the effectiveness of chest compressions and pulmonary blood flow—higher values and a reliable waveform indicate better perfusion, and a sudden rise can signal return of spontaneous circulation.

It does not replace pulse oximetry, which measures oxygen saturation and oxygen delivery rather than ventilation/perfusion in the moment. It also does not measure arterial blood gas directly—that requires an arterial sample. And it does not predict anesthetic depth, which is assessed by other indicators such as volatile agent concentration and physiological responses.