Answer to Question 1
ANS: B
For gas flow to remain constant, delivery pressure must vary inversely with the fourth power of the airway's radius. Reducing the radius of a tube by half requires a 16-fold pressure increase to maintain a constant flow. To maintain ventilation in the presence of narrowing airways, large in-creases in driving pressure may be needed. The energy necessary to generate these pressures can markedly increase the work of breathing.
Answer to Question 2
ANS: A