Low EtCO2 most commonly indicates which ventilatory pattern?

Low EtCO2 most commonly indicates which ventilatory pattern?

• A. Hyperventilation
• B. Hypoventilation
• C. Normal arterial CO2
• D. Cardiac arrest

Answer: (A)

End-tidal CO2 reflects how well CO2 produced by metabolism is eliminated by ventilation, measured at the end of an exhaled breath. When someone hyperventilates, they blow off CO2 faster than it is produced, so alveolar and end-tidal CO2 levels drop. That makes a low EtCO2 most commonly signal a hyperventilatory pattern. If ventilation were reduced (hypoventilation), EtCO2 would rise because CO2 isn’t being eliminated as efficiently. Normal ventilation typically shows normal EtCO2, and very low EtCO2 in cardiac arrest relates more to poor circulation delivering CO2 to the lungs than to a ventilatory pattern.

End-tidal CO2 reflects how well CO2 produced by metabolism is eliminated by ventilation, measured at the end of an exhaled breath. When someone hyperventilates, they blow off CO2 faster than it is produced, so alveolar and end-tidal CO2 levels drop. That makes a low EtCO2 most commonly signal a hyperventilatory pattern. If ventilation were reduced (hypoventilation), EtCO2 would rise because CO2 isn’t being eliminated as efficiently. Normal ventilation typically shows normal EtCO2, and very low EtCO2 in cardiac arrest relates more to poor circulation delivering CO2 to the lungs than to a ventilatory pattern.