CBSSA 7

Question 1

Why does rate of expiratory flow decrease linearly as forced exhalation continues?

Answer 1

this is explained by the concept called “Dynamic compression of the airways” - this compression occurs during forced expiration and limits the flow rate after the first second (FEV1) of exhalation

Question 2

Man with fever, chills, bilateral inspiratory crackles and diffuse wheezing - sputum cultures show Legionella pneumo - organism is in alveoli - which mechanism is most integral to clearing this organism?

Answer 2

T lymphocyte-mediated immunity - Legionella pneumophila is an intracellular pathogen so you require cell-mediated immunity to clear it!

Question 3

patient treated for ARDS - what is most likely found in this person with RESOLVED ARDS

Answer 3

You’d see a decreased diffusion capacity - especially for gases that are diffusion limited (such as CO) due to alveolar damage/fibrosis

Recall there are perfusion-limited (oxygen & nitrous oxide) in normal conditions and then diffusion-limited (like carbon monoxide)