If alveolar ventilation doubles and CO2 production remains constant, PaCO2 will:

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Multiple Choice

If alveolar ventilation doubles and CO2 production remains constant, PaCO2 will:

PaCO2 reflects the balance between CO2 production and alveolar ventilation. At steady state, PaCO2 is proportional to CO2 production divided by alveolar ventilation (PaCO2 ≈ VCO2/VA). If CO2 production stays the same but alveolar ventilation doubles, CO2 is blown off twice as fast, so less CO2 accumulates in the blood. The steady-state PaCO2 falls by about half. For example, if resting PaCO2 is around 40 mmHg, doubling ventilation would bring it toward ~20 mmHg, assuming no other changes. This is why increased ventilation lowers PaCO2; the effect is an inverse relationship with ventilation.

PaCO2 reflects the balance between CO2 production and alveolar ventilation. At steady state, PaCO2 is proportional to CO2 production divided by alveolar ventilation (PaCO2 ≈ VCO2/VA). If CO2 production stays the same but alveolar ventilation doubles, CO2 is blown off twice as fast, so less CO2 accumulates in the blood. The steady-state PaCO2 falls by about half. For example, if resting PaCO2 is around 40 mmHg, doubling ventilation would bring it toward ~20 mmHg, assuming no other changes. This is why increased ventilation lowers PaCO2; the effect is an inverse relationship with ventilation.

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