During the first minute of apnea, the PaCO2 rises by approximately how many mm Hg per minute?

During the first minute of apnea, the PaCO2 rises by approximately how many mm Hg per minute?

• A. 2
• B. 4
• C. 6
• D. 8

Answer: (C)

When ventilation stops, CO2 continues to be produced by tissues but is no longer being eliminated by the lungs. In a healthy adult, the PaCO2 commonly rises about 6 mm Hg per minute during the first minute of apnea. This rate is a widely used rule of thumb in anesthesia to estimate how quickly CO2 accumulates without ventilation. While individual variation exists, 6 mm Hg per minute best fits the typical early rise, whereas the other values are less representative of that initial interval.

When ventilation stops, CO2 continues to be produced by tissues but is no longer being eliminated by the lungs. In a healthy adult, the PaCO2 commonly rises about 6 mm Hg per minute during the first minute of apnea. This rate is a widely used rule of thumb in anesthesia to estimate how quickly CO2 accumulates without ventilation. While individual variation exists, 6 mm Hg per minute best fits the typical early rise, whereas the other values are less representative of that initial interval.