Which of the following occur with positive-pressure ventilation (PPV)?

1. During inspiration, pleural pressure decreases.
2. During inspiration, pressure in the alveoli increases.
3. The pressure gradients of normal breathing are reversed.
4. During inspiration, alveolar pressure exceeds pleural pressure.
a. 1 and 3 only
b. 1, 2, and 3 only
c. 3 and 4 only
d. 2, 3, and 4 only

ANS: D
Because alveolar pressure is greater than pleural pressure (Ppl) during PPV, positive pressure is transmitted from the alveoli to the pleural space, causing pleural pressure to increase during in-spiration.