What happens to end-tidal CO2 as disease severity increases in CF?

What happens to end-tidal CO2 as disease severity increases in CF?

• A. Remains unchanged
• B. Decreases with disease severity
• C. Increases with disease severity
• D. Fluctuates randomly

Answer: (C)

End-tidal CO2 rises as disease severity increases because CO2 elimination worsens as lung function deteriorates in CF. Capnography measures the CO2 concentration at the end of exhalation, which reflects how well alveolar ventilation is removing CO2. In CF, progressive mucus plugging, airway obstruction, and bronchiectasis lead to areas of poor ventilation and, ultimately, hypoventilation in more advanced disease. With less effective ventilation, CO2 accumulates in the blood, and the amount of CO2 exhaled at the end of a breath increases, so the end-tidal CO2 value climbs. In milder disease, ventilation may still compensate enough to keep ETCO2 near normal, but as severity worsens, CO2 retention becomes more evident.

End-tidal CO2 rises as disease severity increases because CO2 elimination worsens as lung function deteriorates in CF. Capnography measures the CO2 concentration at the end of exhalation, which reflects how well alveolar ventilation is removing CO2. In CF, progressive mucus plugging, airway obstruction, and bronchiectasis lead to areas of poor ventilation and, ultimately, hypoventilation in more advanced disease. With less effective ventilation, CO2 accumulates in the blood, and the amount of CO2 exhaled at the end of a breath increases, so the end-tidal CO2 value climbs. In milder disease, ventilation may still compensate enough to keep ETCO2 near normal, but as severity worsens, CO2 retention becomes more evident.