What is the normal end-tidal CO2 range on capnography?

What is the normal end-tidal CO2 range on capnography?

• A. 15-25 mmHg
• B. 0-5 mmHg
• C. 35-45 mmHg
• D. 60-80 mmHg

Answer: (C)

End-tidal CO2 is the CO2 level measured at the end of an exhaled breath, captured by capnography to reflect alveolar ventilation. In a healthy adult, this value normally sits around 35-45 mmHg. It’s usually a bit lower than the arterial CO2 (PaCO2) because some gas in the dead space is exhaled before taking in fully equilibrated air. Values in the 35-45 range indicate normal ventilation and CO2 elimination. The other ranges are not consistent with normal physiology: 15-25 mmHg would mean hypocapnia from over-ventilation, 0-5 mmHg is essentially no CO2 elimination, and 60-80 mmHg indicates marked hypercapnia from inadequate ventilation.

End-tidal CO2 is the CO2 level measured at the end of an exhaled breath, captured by capnography to reflect alveolar ventilation. In a healthy adult, this value normally sits around 35-45 mmHg. It’s usually a bit lower than the arterial CO2 (PaCO2) because some gas in the dead space is exhaled before taking in fully equilibrated air. Values in the 35-45 range indicate normal ventilation and CO2 elimination. The other ranges are not consistent with normal physiology: 15-25 mmHg would mean hypocapnia from over-ventilation, 0-5 mmHg is essentially no CO2 elimination, and 60-80 mmHg indicates marked hypercapnia from inadequate ventilation.