The concept of apnea oxygenation is based on which principle?

• A. Oxygen uptake by the alveoli will continue, even if the diaphragm is not moving
• B. Oxygen saturation requires diaphragmatic movement
• C. Capnography readings rely on chest movement
• D. Oxygenation stops during apnea

Answer: (A)

The main idea is that oxygenation can continue even without breathing motion because oxygen moves by diffusion from the alveolar air into the blood as long as the alveolar oxygen tension stays high. If the airway is well preoxygenated and kept open, the alveoli remain rich in O2, so oxygen diffuses across the alveolar–capillary membrane into the blood despite no diaphragmatic movement. The driving force is the gradient between alveolar O2 and blood O2; movement of the chest isn’t required for that diffusion to occur. This lets oxygenation continue during apnea, though CO2 will accumulate. The other statements aren’t correct because oxygen diffusion and saturation don’t require diaphragm motion, capnography reflects CO2 in exhaled gas rather than chest movement, and oxygenation does not inherently stop during apnea if the alveolar O2 tension is maintained.