Which ETCO2 value defines hypercapnia in anesthesia?

Which ETCO2 value defines hypercapnia in anesthesia?

• A. >50 mmHg
• B. <35 mmHg
• C. >45 mmHg
• D. 35-45 mmHg

Answer: (C)

End-tidal CO2 reflects how well we’re venting and how much CO2 is in the blood. The usual upper limit of normal is about 45 mmHg, so hypercapnia is defined when ETCO2 exceeds this value. Values above 45 mmHg indicate inadequate ventilation or increased CO2 production that anesthesia care must address. Lower values like 35–45 mmHg are normal, and anything below 35 mmHg is hypocapnia. A value above 50 mmHg would be more clearly severe hypercapnia, but the standard cutoff used to define hypercapnia is ETCO2 >45 mmHg.

End-tidal CO2 reflects how well we’re venting and how much CO2 is in the blood. The usual upper limit of normal is about 45 mmHg, so hypercapnia is defined when ETCO2 exceeds this value. Values above 45 mmHg indicate inadequate ventilation or increased CO2 production that anesthesia care must address. Lower values like 35–45 mmHg are normal, and anything below 35 mmHg is hypocapnia. A value above 50 mmHg would be more clearly severe hypercapnia, but the standard cutoff used to define hypercapnia is ETCO2 >45 mmHg.