What is the normal range for end-tidal CO2 (EtCO2)?

What is the normal range for end-tidal CO2 (EtCO2)?

• A. 25-35 mmHg
• B. 30-40 mmHg
• C. 35-45 mmHg
• D. 40-50 mmHg

Answer: (C)

End-tidal CO2 is the CO2 level measured at the end of expiration and serves as a noninvasive gauge of how well CO2 is being eliminated by the lungs. In a healthy adult, the normal range is 35-45 mmHg. This reflects balanced ventilation and CO2 production, with only a small difference between what’s in the alveoli and what's in arterial blood (typically about 2-5 mmHg lower for EtCO2 than PaCO2). Values below this range indicate hyperventilation or excessive CO2 removal, while values above suggest hypoventilation, increased CO2 production, or potential ventilation issues such as rebreathing. The classic reference range used in anesthesia and critical care for EtCO2 sits at 35-45 mmHg, making it the best answer.

End-tidal CO2 is the CO2 level measured at the end of expiration and serves as a noninvasive gauge of how well CO2 is being eliminated by the lungs. In a healthy adult, the normal range is 35-45 mmHg. This reflects balanced ventilation and CO2 production, with only a small difference between what’s in the alveoli and what's in arterial blood (typically about 2-5 mmHg lower for EtCO2 than PaCO2). Values below this range indicate hyperventilation or excessive CO2 removal, while values above suggest hypoventilation, increased CO2 production, or potential ventilation issues such as rebreathing. The classic reference range used in anesthesia and critical care for EtCO2 sits at 35-45 mmHg, making it the best answer.