Normal ETCO2 range?

Normal ETCO2 range?

• A. 30-43
• B. 20-40
• C. 40-58
• D. 25-35

Answer: (A)

End-tidal CO2 is the CO2 concentration at the end of expiration, measured by capnography to monitor ventilation and circulation. In healthy adults, ETCO2 values are close to arterial CO2 but typically a few millimeters of mercury lower due to dead space air that is rebreathed or not fully exchanged. This gives a normal approximate range around 30-43 mmHg, with many clinicians commonly targeting about 35-40 mmHg depending on the situation. The range 30-43 mmHg best reflects this typical variability and the physiologic relationship to PaCO2. Values much lower (around 20-25) would indicate excessive ventilation or poor measurement, while values much higher (above the low 40s into the 50s) would suggest hypoventilation or rebreathing; the narrower 25-35 range would exclude many normal end-tidal values.

End-tidal CO2 is the CO2 concentration at the end of expiration, measured by capnography to monitor ventilation and circulation. In healthy adults, ETCO2 values are close to arterial CO2 but typically a few millimeters of mercury lower due to dead space air that is rebreathed or not fully exchanged. This gives a normal approximate range around 30-43 mmHg, with many clinicians commonly targeting about 35-40 mmHg depending on the situation. The range 30-43 mmHg best reflects this typical variability and the physiologic relationship to PaCO2. Values much lower (around 20-25) would indicate excessive ventilation or poor measurement, while values much higher (above the low 40s into the 50s) would suggest hypoventilation or rebreathing; the narrower 25-35 range would exclude many normal end-tidal values.