Inhalation of CO2 increases minute ventilation by what range of L/min per mm Hg PaCO2?

Inhalation of CO2 increases minute ventilation by what range of L/min per mm Hg PaCO2?

• A. 0.5 to 1 L/min/mm Hg
• B. 2 to 3 L/min/mm Hg
• C. 3 to 5 L/min/mm Hg
• D. 5 to 10 L/min/mm Hg

Answer: (B)

The main idea is how ventilation responds to carbon dioxide levels. Central chemoreceptors in the brain sense the CO2-driven pH change in cerebrospinal fluid and stimulate the respiratory drive, so minute ventilation increases as PaCO2 rises. In a healthy adult, this ventilatory drive increases by about 2 to 3 liters per minute for every 1 mm Hg increase in PaCO2. This gives a roughly linear relationship within the normal range of PaCO2. So for a small rise in PaCO2, you’d expect VE to jump by about 2–3 L/min for each mm Hg increase. Of course, individual factors like age, conditioning, anesthesia, or lung disease can shift this slope, but the standard teaching value is 2–3 L/min per mm Hg.

The main idea is how ventilation responds to carbon dioxide levels. Central chemoreceptors in the brain sense the CO2-driven pH change in cerebrospinal fluid and stimulate the respiratory drive, so minute ventilation increases as PaCO2 rises. In a healthy adult, this ventilatory drive increases by about 2 to 3 liters per minute for every 1 mm Hg increase in PaCO2. This gives a roughly linear relationship within the normal range of PaCO2. So for a small rise in PaCO2, you’d expect VE to jump by about 2–3 L/min for each mm Hg increase. Of course, individual factors like age, conditioning, anesthesia, or lung disease can shift this slope, but the standard teaching value is 2–3 L/min per mm Hg.