Does PEEP affect CO2 elimination?

Does PEEP affect CO2 elimination?

• A. Yes
• B. No
• C. Sometimes
• D. Not at all

Answer: (B)

CO2 elimination is determined mainly by alveolar ventilation—the amount of fresh gas reaching and leaving the alveoli each minute—along with how well CO2 transfers from blood to the alveolar air. PEEP’s job is to keep alveoli open at end expiration to improve oxygenation and reduce shunt. It does not directly drive CO2 removal. If you keep the same minute ventilation, increasing or adjusting PEEP won’t change the amount of CO2 you eliminate. Any effect on CO2 would be indirect—through changes in lung compliance or the need to adjust tidal volume or respiratory rate to maintain the same alveolar ventilation. So CO2 elimination is not directly affected by PEEP.

CO2 elimination is determined mainly by alveolar ventilation—the amount of fresh gas reaching and leaving the alveoli each minute—along with how well CO2 transfers from blood to the alveolar air. PEEP’s job is to keep alveoli open at end expiration to improve oxygenation and reduce shunt. It does not directly drive CO2 removal. If you keep the same minute ventilation, increasing or adjusting PEEP won’t change the amount of CO2 you eliminate. Any effect on CO2 would be indirect—through changes in lung compliance or the need to adjust tidal volume or respiratory rate to maintain the same alveolar ventilation. So CO2 elimination is not directly affected by PEEP.