What is the distal consequence of a completely obstructed airway?

• A. Air is resorbed and alveoli collapse
• B. Airways dilate
• C. Excess air accumulates due to air trapping
• D. Immediate pneumothorax

Answer: (A)

When the airway is completely blocked, ventilation to the distal airways stops. The oxygen in the alveolar gas diffuses into the blood and is not replenished, so the alveolar air is resorbed. As the gas is absorbed, the alveoli collapse, producing resorption (absorptive) atelectasis. The other ideas don’t fit because there is no ventilation to cause dilation or trapping, and a pneumothorax would require rupture into the pleural space, not an automatic distal consequence of complete obstruction.