Vignette #1:
Jenny Smith, a 14-year-old girl with asthma, had been under
relatively good control until last night. She slept over at a friend's
house and woke up in the middle of the night with severe shortness of
breath ("dyspnea") and a cough (unproductive of sputum). She had expiratory
wheezing. Unfortunately, she did not take her bronchodilator medication
with her to her friend's house. She was taken to the emergency walk-in
clinic. On physical exam, she was wheezing quite loudly and using her
accessory muscles of respiration to help her breathe. A chest X-ray revealed
hyperluscent and over-inflated lungs. Blood testing revealed an arterial
blood pH of 7.25 (normal = 7.35-7.45). Pulmonary function testing revealed
the graph shown below.
Questions:
Based on the graph, fill in the following data:
1. tidal volume ____________
inspiratory reserve volume ______________
expiratory reserve volume _______________
forced vital capacity ______________
Answer
2. What is her FEV1
/ FVC ratio?
Does this ratio indicate restrictive or obstructive lung disease?
Answer
3. She is given a
bronchodilator called theophylline that makes her breathe more easily,
after which pulmonary function tests are repeated. Describe how a graph of her
"post-bronchodilator" lung volumes would look. (A sample graph has been provided.)
Answer
4. The theophylline she was given is a methyl xanthine. How does this
drug help dilate the bronchioles?
Answer
5. Why was her arterial
blood pH lower than normal? What is this condition called?
Answer
Vignette #2:
James Fishel is a 56-year-old maintenance worker who has worked for
the same company for 32 years, spending most of his time installing and
removing insulation from buildings. He saw his physician with complaints
of becoming increasingly short of breath over the past year, particularly
when he is exerting himself. He notes that "just getting enough air in"
is exhausting. A chest X-ray revealed a "shaggy" (i.e. blurred) heart
border and a hazy appearance of the lungs. Pulmonary function testing
was done and the results are shown below.
Questions:
Based on the graph, fill in the following data:
1. tidal volume ____________
inspiratory reserve volume ______________
expiratory reserve volume _______________
forced vital capacity ______________
Answer
2.
What is the FEV1 / FVC ratio?
What pattern of lung disease may result in this ratio?
Answer
3. How has his lung compliance changed over the years?
Answer
4. What specifically
do you think caused his lung disease?
Answer
5. Do you know of
any other respiratory conditions that result in this pattern of lung
disease?
Answer
Vignette #3:
Joe Smith is a 69-year-old male with a 50-year history of smoking 2
packs of cigarettes a day (i.e. 100-pack-year smoking history). Over the
past 5 years, he has become increasingly short of breath. At first, he
noticed this only when exercising, but now he is even short of breath
at rest. Over the past two years, he has had several bouts of lower respiratory
tract infection treated successfully with antibiotics. His shortness of
breath hasn't subsided, and his breathing is assisted by use of his accessory
muscles of respiration. Pulmonary function testing revealed the graph
below:
Questions:
Based on the graph, fill in the following data:
1. tidal volume ____________
inspiratory reserve volume ______________
expiratory reserve volume _______________
forced vital capacity ______________
Answer
2. What is the FEV1 / FVC ratio?
What pattern of lung disease may result in this ratio?
Answer
3. Describe the microscopic changes occurring in Joe's lungs.
Answer
4. What effect do these microscopic changes have on Joe's ability to
transfer oxygen and carbon dioxide in the lungs?
Answer
5. Blood testing showed Joe's hematocrit to be 59% (normal = 42-54%).
Why was his hematocrit so high?
Answer
6. Arterial blood tests revealed the following:
| pO2 (partial pressure of oxygen in the plasma) = 73 mm Hg (normal= 80-105 mm Hg) |
| pCO2 (partial pressure of carbon dioxide in the plasma) = 50 mm
Hg (normal 35- 45 mm Hg) |
| pH = 7.32 (normal = 7.35-7.45) |
| Hb-O2 sat (hemoglobin-oxygen saturation) = 84% (normal = 95-98%) |
A. Why was Joe's pCO2 increased above normal?
Answer
B. Why was his arterial blood pH below normal?
Answer
C. Joe's pO2 is clearly below the normal range. One's first instinct
might be to give him air to breathe that is 100% oxygen. Why would this
be dangerous for him?
Answer
7. Why is Joe susceptible to lower respiratory tract infections?
Answer
