During an inspiratory pause, which of the following pressures are equal to the airway pressure? I. pleural pressure II. alveolar pressure III. tracheal pressure IV. esophageal pressure

A. II only
B. I, II only
C. I, IV only
D. II, III only

?ANS: D
A. Incorrect response: See explanation D.
B. Incorrect response: See explanation D.
C. Incorrect response: See explanation D.
D. Correct response: When no gas is flowing, the following three pressures are equal: alveolar pressure, tracheal pressure, and airway pressure. No gas flows during either an inspiratory or expiratory pause. The alveolar pressure is sometimes called the alveolar distending pressure