Which of the following statements applies to a lung unit with ...

[DyllonKazuo]

Which of the following statements applies to a lung unit with higher resistance than normal?
 
  a. A given volume change will require less of a pressure change.
  b. It will fill and empty more rapidly than a normal lung unit.
  c. There will be less volume change for a given pressure change.
  d. Volume to this area will remain the same under all conditions.

Question 2

In patients with small-airway disease breathing at higher than normal frequencies, what is likely to happen?
 
  1. Dynamic compliance drops.
  2. Oxygen consumption decreases.
  3. The distribution of ventilation worsens.
  4. The work of breathing increases.
  a. 1 and 2 only
  b. 1, 2, and 4 only
  c. 2, 3, and 4 only
  d. 1, 2, 3, and 4

[jgranad15]

Answer to Question 1

ANS: C
If the airway is obstructed, high resistance to gas flow can occur in a local area. The pressure drop across the obstruction may be substantial. Less driving pressure is available for alveolar in-flation; thus there is less alveolar volume change.

Answer to Question 2

ANS: B
Compliance of the lung appears to decrease as breathing frequency increases. This phenomenon is called frequency dependence of compliance. Compliance measured during breathing is dynamic as it includes pressure changes created by resistance to airflow. If dynamic compliance decreases as the respiratory rate increases, some lung units must have abnormal time constants. Any stimu-lus to increase ventilation, such as exercise, may redistribute inspired gas. Mismatching of venti-lation and perfusion can result in hypoxemia, severely limiting an individual's ability to perform daily activities. In addition the increased breathing frequency and decreased dynamic compliance may result in significant increases in oxygen consumption.