Case 1
A 65 year-old man undergoes pulmonary function testing as part of a routine healthscreening test. He has no pulmonary complaints. He has never been a s smoker but has a
history of asbestos exposure while serving in the Navy. His pulmonary function test
results are as follows:
Test
FVC (L)
FEV1 (L)
FEV1/FVC (%)
FRC (L)
ERV (L)
RV (L)
TLC (L)
Actual
4.39
3.20
73
3.17
0.63
2.54
6.86
Predicted
4.32
3.37
78
3.25
0.93
2.32
6.09
% Predicted
102
95
98
68
109
113
Question 1.1
How would you classify the pattern of test results for this patient?
A. Normal spirometry and lung volumes  correct & explanation
B. Obstructive pattern  incorrect, try again
C. Restrictive pattern  incorrect, try again
D. Mixed obstructive and restrictive patterns  incorrect, try again
Explanation for Question 1
Pulmonary function tests can be used to characterize a patient’s respiratory function
abnormalities and this information, can be used, in turn, to guide further diagnostic workup and management for the patient. Each parameter that is measured can be expressed as
an absolute value as well as relative to the predicted value of that parameter for that
particular patient. This is often referred to as “percent of predicted” with the predicted
value being a function of the patient’s age, gender, height, weight and race. The different
parameters listed in the table above and their normal ranges are listed below:
•
The forced expiratory volume in one second (FEV1) is the volume of gas exhaled
in the first second of a forced exhalation maneuver. The FEVl is deemed to be
normal if it is greater than 80% of the predicted value.
•
The forced vital capacity (FVC) is the entire volume of gas exhaled during a
forced exhalation maneuver. The FVC is deemed to be normal if it is greater than
80% of the predicted value. This maneuver can sometimes be performed with a
slow exhalation in which case it is referred to as a Slow Vital Capacity (SVC).
•
The FEV1/FVC is the absolute value of the FEV1 divided by the absolute value of
the FVC. Note that the units for these two parameters cancel and the ratio has no
units. It is typically expressed as a decimal (e.g., 0.7). The lower limit of normal
for this parameter varies based on which authority you consult. The Global
Initiative for Obstructive Lung Disease (GOLD) and the American Thoracic
Society and European Respiratory Society (ATS/ERS) guidelines set the lower
limit of normal as 0.7. At the University of Washington, the lower limit of normal
is determined by taking the predicted ratio for that patient and subtracting 0.08 if
the patient is a man and 0.09 if the patient is a woman. For example, if you had a
male patient and the predicted ratio was 0.76, the lower limit of normal for this
patient’s FEV1/FVC ratio would be 0.68. Values below that would be considered
abnormal.
•
The total lung capacity (TLC) is the maximal volume of the lungs. It is
considered to be normal if it falls between 80% and 120% of the predicted value.
•
The residual volume (RV) is the volume of air left in the lungs at the end of a
forced expiration. The normal range for this parameter is between 80% and 120%
of the predicted value.
Based on the observed values for the parameters described above, we can describe
several basic patterns of abnormalities on pulmonary function tests including:
•
Normal: The FEV1/FVC ratio is above the lower limit of normal and the TLC
resides between 80 and 120% predicted.
•
Obstructive pattern: is marked by reductions in the FEV1 and FVC and the
FEV1/FVC ratio. The reduced FEV1/FVC ratio is considered the sine qua non of
the obstructive pattern and a patient cannot be deemed to have this pattern unless
this abnormality is present. In some cases, the SVC can be substituted for the
FVC in order to calculate this ratio.
•
Restrictive pattern: is marked by reductions in the FEV1 and FVC but a
preserved (i.e., normal FEV1/FVC ratio) and a reduced TLC. The reduction in
FEV1 and FVC with a preserved ratio is only suggestive of the diagnosis of
restriction, however, and the TLC must be reduced in order to label a patient as
having a restrictive defect.
•
Mixed obstructive and restrictive pattern: is present when the patient has both
a reduced FEV1/FVC ratio and the TLC is less than 80% of the predicted value.
In this case, the FEV1, FVC, FEV1/FVC are normal, indicating there is no evidence of an
obstructive defect. Because the TLC is 113% of predicted, the patient does not have a
restrictive defect either. As a result, this patient has normal spirometry and lung volumes.
Case 2
A 54 year-old man presents to his primary care provider with dyspnea, cough and
intermittent chest tightness. His cough is worse at night, in the early morning and with
exercise. He is a non-smoker with no relevant occupational exposures.
Test
FVC (L)
FEV1 (L)
FEV1/FVC (%)
Pre-Bronchodilator (BD)
Actual
Predicted
% Predicted
3.19
4.22
76
2.18
3.39
64
68
80
Post- BD
Actual
% Change
4.00
25
2.83
30
71
4
Question 2.1
How would you classify the pattern of test results for this patient?
A. Normal spirometry  incorrect, please try again
B. Obstructive pattern  correct & explanation
C. Restrictive pattern  incorrect, please try again
D. Mixed obstructive and restrictive pattern  incorrect, please try again
Question 2.1 Explanation:
If you use the criteria set forth by GOLD and the ATS/ERS, the actual ratio of 0.68 is
below the 0.7 cutoff and the patient has an obstructive defect. If you use the criteria used
at the University of Washington, the patient’s predicted ratio is 0.80. Given that this is a
male patient, the lower limit of normal is determined by subtracting 0.08 from that value
(0.72). His actual ratio of 0.68 falls below that cut-off as well so he would also be
deemed to have airflow obstruction by this criterion.
Question 2.2
How would you rate the severity of the observed abnormality?
A. Mild defect  incorrect, please try again
B. Moderate defect  correct & explanation
C. Severe defect  incorrect, please try again
D. Very severe defect  incorrect, please try again
Question 2.2 Explanation
For obstructive patterns, the severity is graded based on the decrement in the FEV1.
•
•
•
•
> 80% predicted: mild obstruction
> 50% and < 80% predicted: moderate obstruction
> 30% and < 50% predicted: severe obstruction
< 30% predicted: very severe obstruction
Restrictive defects are graded based on the decrement in the TLC.
•
•
•
> 65% and < 80% predicted: mild restriction
> 50% and < 65% predicted: moderate restriction
< 50% predicted: severe restriction
In this case, the FEV1 is reduced to 64% of predicted, indicating that the patient has
moderate obstruction
Question 2.3
Does the patient have a bronchodilator response?
A. Yes  correct
B. No  incorrect
(Brian Valentine: Either answer should forward them to the explanation since it’s
basically a 50/50 shot and sending them to guess again has no learning value.)
Question 2.3 Explanation
A bronchodilator response is defined as a 200 mL and 12% increase in the FEV1
or FVC following bronchodilator administration In this case, there was an improvement
of 25% (and 810 mL) in the FVC and 30% (and 650 mL) in the FEV1 so the patient
would be classified as having a bronchodilator response.
The presence of a bronchodilator response can be used to make a diagnosis of asthma,
since the hallmark of that disorder is reversible airflow obstruction and the presence of a
bronchodilator response demonstrates some evidence of reversibility. Keep in mind that
although some patients with COPD may not demonstrate a bronchodilator response on
pulmonary function testing, bronchodilators are still the mainstay of therapy in this
patient population, as they still derive symptomatic benefit from their administration.
Case 3
A 60 year-old man presents to his primary care provider with complaints of increasing
dyspnea on exertion. He has a 40 pack-year history of smoking and is retired following a
career as a building contractor. His pulmonary function testing is as follows:
Test
FVC (L)
FEV1 (L)
FEV1/FVC (%)
RV (L)
TLC (L)
RV/TLC (%)
DLCO corr
Pre-Bronchodilator (BD)
Actual
Predicted
% Predicted
1.89
4.58
41
0.89
3.60
25
47
79
5.72
2.31
248
7.51
6.41
117
76
37
15.73
33.43
47
Post- BD
Actual
% Change
3.69
96
1.89
112
Question 3.1
How would you classify the pattern of test results for this patient?
A. Normal spirometry  incorrect, please try again
B. Moderate obstructive defect  incorrect, please try again
C. Very severe obstructive defect  correct and explanation
D. Restrictive pattern  incorrect, please try again
Question 3.1 Explanation
The patient has a low FEV1 and low FVC and the ratio is reduced. This pattern is
consistent with an obstructive pattern. The TLC is normal, as it falls between 80 and
120% of predicted and, therefore, there is no evidence of restriction. Because the FEV1 is
< 30% of predicted, this would be classified as a very severe obstructive process.
Question 3.2
Based on the information provided, how else can you characterize this patient’s
pulmonary function?
A. Air-trapping  correct, explanation
B. Hyperinflation  incorrect, please try again
C. Air-trapping and hyperinflation  incorrect, please try again
D. No bronchodilator response  incorrect, please try again
Question 3.2 Explanation
When the residual volume (RV) (the volume of gas remaining in the lungs at the end of a
forced expiration) is greater than 120% of predicted, the patient is deemed to have
evidence of air-trapping. If the total lung capacity (TLC) is greater than 120% of
predicted, the patient is deemed to have hyperinflation. Air-trapping and hyperinflation
are findings that help characterize the patients physiologic abnormalities better but are
not necessary to confirm the diagnosis of air-flow obstruction. Many patients with
airflow obstruction based on the low FEV1/FVC ratio will have a normal RV and/or TLC.
This patient’s RV is 248% of predicted while the TLC is only 117% predicted, indicating
that he has air-trapping but not hyperinflation.
Question 3.3
What conclusions can you draw from the patient’s DLCO?
A. Normal DLCO  incorrect, please try again
B. Reduced DLCO indicating a loss of surface area for gas exchange  correct &
explanation
C. Reduced DLCO indicating that he likely has polycythemia  incorrect, please try
again
D. Reduced DLCO indicating high levels of carboxyhemoglobin in his blood from
smoking incorrect, please try again
Question 3.3 Explanation
The DLCO is the diffusing capacity of the lung for carbon monoxide. This parameter gives
us information about the adequacy of the surface area for gas exchange and can be used
along with spirometry and lung volumes to understand the patient’s underlying
physiology and generate a differential diagnosis.
• In patients with obstructive defects on spirometry, a reduced DLCO suggests they have
underlying emphysematous changes as the source of the reduced surface area for gas
exchange.
• A reduced DLCO with normal spirometry and lung volumes may suggest anemia.
• In patients with restrictive lung disease, a reduced DLCO suggests that the restrictive
physiology is due to a process intrinsic to the lung (e.g., idiopathic pulmonary
fibrosis). A normal DLCO would indicate that restriction is due to something outside
the lungs (e.g., chest wall or neuromuscular disorders)
• Patients with pulmonary hypertension in the absence of underlying parenchymal lung
disease often have an isolated decrease in their DLCO but otherwise normal spirometry
and lung volumes.
• In patients with diffuse alveolar hemorrhage, the DLCO may actually be elevated as
the intra-alveolar red blood cells take up the carbon monoxide administered during
the test quite readily.
Question 3.4: A series of flow volume loops are shown below, with volume on the X
axis and flow on the Y axis. The expiratory phase is represented by the top portion (flow
is positive) and the inspiratory phase is represented by the bottom portion (flow is
negative).
A
B
Question 3.4
Which of the flow volume loop above is most consistent with the pulmonary function
test results provided earlier in this case
A. Figure A  correct and explanation
B. Figure B  incorrect, please try again
Question 3.4 Explanation
The patient in this case has severe obstruction, characterized by an FEV1 between 30%
and 50%. The expiratory phase is represented by the top portion of the graph (positive
flow and volume). The flow volume loop in obstructive lung disease typically has a
“scooped out” appearance due to prolongation of the expiratory phase.
Panel B shows the typical pattern seen in patients with restrictive defects. The curve often
has a short, “stubby” appearance (or convex pattern2) and expiration ends after a small
volume has been expired.
Case 4
A 25 year-old man presents to his physician with complaints of dyspnea and wheezing.
He is a non-smoker. Two years ago, he was in a major motor vehicle accident and was
hospitalized for 3 months. He had a tracheostomy placed because he remained on the
ventilator for a total of 7 weeks. His tracheostomy was removed 2 months after his
discharge from the hospital. His pulmonary tests are as follows:
Test
FVC (L)
FEV1 (L)
FEV1/FVC (%)
Actual
4.73
2.56
54
Pre-Bronchodilator (BD)
Predicted
% Predicted
4.35
109
3.69
69
85
Question 4.1
How would you characterize the results of his pulmonary function tests?
A. Normal spirometry  incorrect, please try again
B. Consistent with a restrictive process  incorrect, please try again
C. Mild obstructive defect  incorrect, please try again
D. Moderate obstructive defect > correct & explanation
E. Severe obstructive defect  incorrect, please try again
Question 4.1 Explanation
The patient has a low FEV1 and FVC and a low FEV1/FVC ratio, consistent with an
obstructive process. The FEV1 is 69% of predicted, indicating that the patient has a
moderate obstructive defect.
Question 4.2
The flow-volume loop for this patient is provided below.
Based on this flow-volume loop, how can you further characterize this patient’s
pulmonary function abnormality:
A.
B.
C.
D.
E.
No upper airway obstruction  incorrect, please try again
Variable intrathoracic upper airway obstruction  incorrect, please try again
Variable extrathoracic upper airway obstruction  incorrect, please try again
Fixed upper airway obstruction  correct & explanation
Unilateral mainstem bronchus obstruction  incorrect, please try again
Question 4.2 Explanation
When interpreting pulmonary function tests, it is important to look at the flow volume
loops and not just look at the numbers. The reason for doing so is that occasionally the
flow volume loop will take on a characteristic appearance suggestive of a particular
diagnosis that might not be apparent from looking at the numbers alone. In addition to the
patterns typically seen in obstructive and restrictive processes described in the previous
case, there are four patterns that might appear on flow volume loop in patients with
obstructive physiology that would change your differential diagnosis and affect your
further diagnostic work-up.
•
Variable Intrathoracic Obstruction (Panel ___): This is caused by lesions
within the intrathoracic airways (i.e., within the chest cavity) that obstruct the
lumen of the airway but move in response to airway pressure changes during the
respiratory cycle. In such cases, there is flattening of the expiratory portion of the
flow-volume loop. An example of such a process would be
tracheobronchomalacia in which there is breakdown of the cartilaginous rings that
support the airway structure leading to airway collapses on exhalation.
•
Variable Extrathoracic Obstruction (Panel ___): This pattern is caused by
lesions within the extrathoracic airways (i.e., outside the chest cavity) that
obstruct the lumen of the airway but move in response to airway pressure changes
during the respiratory cycle. In such cases, there is flattening of the inspiratory
portion of the flow-volume loop. An example of a process that could cause this
problem would be a mobile thyroid mass compressing the trachea.
•
Fixed Airway Obstruction (Panel ___): This pattern is caused by either an
intrathoracic or extrathoracic lesion that obstructs the airway lumen but does not
move in response to airway pressure changes during the respiratory cycle. In such
cases, there is flattening of both the inspiratory and expiratory limbs of the flowvolume loop. An example of a process that could cause this abnormality would be
tracheal stenosis or bulky lymphadenopathy encasing the trachea.
•
Differential Emptying From The Two Lungs (Panel ___): In some cases, one
lung empties normally on exhalation, while emptying of the other lung is delayed
due to some process occluding the airway. In such cases, the flow volume loop
will appear to have two phases: (1) a rapidly descending portion of the expiratory
limb representing emptying of the normal lung and (2) a flat portion of the
expiratory limb represents the delayed emptying on the obstructed side. Such a
pattern might be seen with a tumor obstructing one of the mainstem bronchi.
This patient’s flow volume loop shows flattening of both the inspiratory and expiratory
limbs, indicating that he has some process obstructing the airway that does not move with
the respiratory cycle. This would be consistent with a fixed airflow obstruction (Panel
___ above). Given that he previously had a tracheostomy, this pattern would raise
suspicion that he might have tracheal stenosis due to granulation tissue formation at the
tracheostomy site. He needs further work-up including bronchoscopy to evaluate this
issue.
This case illustrates why it is important to look at the flow-volume loops when
interpreting pulmonary function tests. If all one did was look at the numerical results, the
patient would be labeled as having airflow obstruction and, given his age, would in all
likelihood be given the diagnosis of asthma. With this diagnosis, he would be started on
inhaled corticosteroids and bronchodilators which, given the likely diagnosis, would not
improve his symptoms and, instead, would only serve to delay definitive diagnosis.
Identifying the true problem by analyzing the flow volume loop will ensure he gets the
appropriate work-up and treatment.
Case 5
A 41 year-old woman presents to the General Internal Medicine Clinic complaining of
dyspnea with mild exertion. She has a 10 pack-year history of smoking and a history of
using intravenous drugs including heroin and Ritalin (methylphenidate). Her pulmonary
function tests are as follows:
Test
FVC (L)
FEV1 (L)
FEV1/FVC (%)
RV (L)
TLC (L)
RV/TLC (%)
DLCO corr
Pre-Bronchodilator (BD)
Actual
Predicted
% Predicted
0.90
3.09
29
0.49
2.57
19
54
83
3.83
1.49
257
4.78
4.44
108
80
33
0.75
24.85
3
Post- BD
Actual
% Change
0.74
- 17
0.44
-10
59
8
Question 5.1
How would you classify the pattern of test results for this patient?
A. Normal spirometry and lung volumes  incorrect, try again
B. Obstructive pattern  correct & explanation
C. Restrictive pattern  incorrect, try again
D. Mixed obstructive and restrictive patterns  incorrect, try again
Question 5.1 Explanation
She has air flow obstruction as seen by reduced FEV1/FVC in addition to a reduced FEV1
and FVC. TLC is within normal limits, so she does not have either restriction or a mixed
obstructive and restrictive pattern. Her FEV1 is 19% predicted and therefore her airflow
obstruction would be classified as “very severe”.
Question 5.2
Her pulmonary function tests reveal which of the following?
A. Air trapping & bronchodilator response  incorrect, please try again
B. Air trapping & reduced DLCO  correct & explanation
C. Hyperinflation & bronchodilator response  incorrect, please try again
D. Hyperinflation & reduced DLCO  incorrect, please try again
E. Reduced DLCO & bronchodilator response  incorrect, please try again
Question 5.2 Explanation
Her RV is 257% predicted and she therefore has air-trapping. Her TLC is 108% of
predicted and does not meet criteria for hyperinflation. Her DLCO is reduced to 3% of the
predicted value. She does not have a bronchodilator response as her FEV1 and FVC are
both decreased following bronchodilator administration.
Question 5.3
Her flow volume loop is as follows:
Which of the following is true regarding her flow volume loop?
A. Normal  incorrect, please try again
B. Airflow obstruction without airway obstruction  correct, explanation
C. Variable extrathoracic airway obstruction  incorrect, please try again
D. Variable intrathoracic airway obstruction  incorrect, please try again
E. Fixed airway obstruction  incorrect, please try again
Question 5.3 Explanation
This flow volume loop represents airflow obstruction without airway obstruction. She
has a concave expiratory limb consistent with the very severe airflow obstruction seen on
her pulmonary function tests. The inspiratory and expiratory limbs are not flattened as
would be seen if she had an obstructing lesion in her airway (e.g., a tumor) causing her
airflow obstruction.
Question 5.4
Her chest radiograph is below.
Taking into account her history and physical pulmonary function test results (very severe
obstruction, air trapping, reduced DLCO), flow volume loop showing airflow obstruction
without airway obstruction, and her chest radiograph above, what is the most likely
clinical diagnosis?
A. Ritalin lung  correct & explanation
B. Chronic obstructive pulmonary disease due to tobacco use  incorrect, please try
again
C. Idiopathic pulmonary fibrosis  incorrect, please try again
D. Hypersensitivity pneumonitis  incorrect, please try again
E. Pulmonary hypertension  incorrect, please try again
Question 5.4 Explanation
Given her relatively young age and the fact that she has only a 10-pack-year history of
smoking, COPD secondary to tobacco use (centrilobular emphysema) would be an
unlikely diagnosis. These patients typically present later in life and often have a more
significant history of tobacco use.
The noteworthy feature of her chest radiograph is
that the bibasilar lung fields are hyperlucent (i.e.,
there is a paucity of lung markings in those areas
and illustrated by the white arrows). Additionally,
the minor fissure on the right is shifted upward
(black arrow), indicating that the lower lungs are
hyper-inflated. These findings are distinct from
those seen smoking-related centrilobular
emphysema which tends to preferentially affect the
upper lung zones more than the lower lung zones
The presence of basilar predominant
emphysematous changes should raise concern for
two possible diagnoses that can cause precocious airflow obstruction and a basilar
predominant pattern of emphysematous changes typical of paraseptal emphysema: α1
antitrypsin and Ritalin lung. The latter is a form of emphysema that has been described in
intravenous drug users who injected methylphenidate and is caused by reaction to talc
that is used in the preparation of the methylphenidate and is injected into the circulation
along with the active drug.3,4 To distinguish between these two entities, you would rely
on clinical history (in this case, the patient has a history of IV Ritalin use) as well as
laboratory testing to rule out alpha-one antitrypsin deficiency.
Case 6
A 30 year-old woman presents for evaluation of a two-month history of dyspnea on
exertion. She is a life-long non-smoker with no prior history of asthma or other
pulmonary problems. She works as a receptionist at a publishing company. She has two
cats and several parakeets at home. Her pulmonary function testing is as follows:
Test
FVC (L)
FEV1 (L)
FEV1/FVC (%)
RV (L)
TLC (L)
RV/TLC (%)
DLCO corr
Pre-Bronchodilator (BD)
Actual
Predicted
% Predicted
1.73
4.37
40
1.57
3.65
43
91
84
1.01
1.98
51
2.68
6.12
44
38
30
5.13
32.19
16
Post- BD
Actual
% Change
1.79
4
1.58
0
88
-3
Her flow volume loop is as follows:
Question 6.1
How would you classify the pattern of test results for this patient?
A. Normal spirometry and lung volumes  incorrect, try again
B. Obstructive pattern  incorrect, try again
C. Restrictive pattern due to an intrinsic pulmonary process correct & explanation
D. Restrictive pattern due to a problem extrinsic to the lung  incorrect, try again
E. Mixed obstructive and restrictive patterns  incorrect, try again
Question 6.1 Explanation
Her results show reduced FEV1 (43% predicted), reduced FVC (40% predicted) but a
preserved FEV1/FVC ratio. This pattern on spirometry is consistent with a restrictive
lung process and the diagnosis of restriction is confirmed by the fact that she has a
reduced TLC.
The DLCO can be used to help sort out whether the restrictive process is due to something
intrinsic to the lung, such as interstitial lung disease, or a process extrinsic to the lung,
such as a neuromuscular disorder. When restriction is due to a process involving the lung
parenchyma, the DLCO will be reduced, indicating that the surface area for gas exchange
is impaired, as you would expect in a process affecting the lung parenchyma. If the
restrictive process is due to something outside the lung, you would expect the pulmonary
parenchyma and surface area for gas exchange to be normal, in which case the DLCO
would be normal. This patient’s DLCO is markedly reduced suggesting that the cause of
her restriction lies within the pulmonary parenchyma
Question 6.2
How would you grade the severity of her restrictive process?
A. Mild  incorrect, please try again
B. Moderate  incorrect, please try again
C. Severe  correct & explanation
D. Very Severe  incorrect, please try again
Explanation to Question 6.2
As noted earlier in Case 2, the severity of the restriction can be classified using the TLC.
65-80% mild restriction
50-65% moderate restriction
<50% severe restriction
There is no category for “very severe” restriction as there is with obstructive processes.
This patient’s TLC is 44% of predicted prior to treatment and, as a result, she would be
labeled as having a “severe” restrictive process.
Question 6.3
What would be the next appropriate step in this patient’s diagnostic work-up?
A. CT Pulmonary Angiogram  incorrect, please try again
B. High resolution Chest CT  correct & explanation
C. Upright and supine spirometry  incorrect, please try again
D. Maximum inspiratory and expiratory pressure measurements  incorrect, please
try again
E. Echocardiogram  incorrect, please try again
Explanation to Question 6.3
When a patient has evidence of restriction with a reduced DLCO, you should always
consider a process intrinsic to the lung as the cause of this abnormality. In particular, you
should be concerned about some form of interstitial lung disease and the most appropriate
diagnostic study to order would be a high resolution Chest CT. Such a study involves
taking thinner slices of the lungs which provide greater detail in the images and allow
better assessment of the parenchymal changes. This study also includes expiratory images
which allow you to distinguish whether there is evidence of air-trapping and prone
images which allow you to determine whether opacities seen in the dependent lung zones
on the supine images are due to atelectasis or interstitial lung disease.
A CT pulmonary angiogram would be used to rule out pulmonary embolism. Upright and
supine spirometry can be used to determine if a patient has diaphragmatic weakness when
you see a restrictive pattern with a normal DLCO while maximum inspiratory and
expiratory pressures can be used to assess for respiratory muscle weakness when you see
a restrictive pattern with a normal DLCO.
Further evaluation including a high resolution Chest CT (shown below) revealed that this
patient had hypersensitivity pneumonitis, likely secondary to her exposure to parakeets at
home. The parakeets were removed from her home and she was given a course of oral
corticosteroids. Following treatment, her repeat pulmonary function tests were improved
as was the CT scan of her chest. The pre- and post-treatment pulmonary function tests
and CT images are shown below:
Pulmonary Function Tests
Pre-Treatment
Test
Actual Predicted % Pred.
FVC (L)
1.73
4.37
40
FEV1 (L)
1.57
3.65
43
FEV1/FVC
91
84
(%)
RV (L)
1.01
1.98
51
TLC (L)
2.68
6.12
44
RV/TLC (%)
38
30
DLCO corr
5.13
32.19
16
Post-Treatment
Actual
Predicted % Pred.
3.00
4.35
69
2.40
3.63
66
80
83
0.70
3.70
19
13.61
1.99
6.11
30
32.04
35
61
42
CT Scan Images
Single slices of the Chest CT in the pre- and post-treatment period. The pre-treatment
image on the left shows extensive “ground glass” opacities. This is best appreciated by
comparing the whiter dependent lung zones with the more normal-appearing anterior
lung zones as well as the darker areas in the periphery of her lung. Ground glass opacities
are a non-specific finding indicative of some type of alveolar-filling process. The alveoli
can be filled with blood, edema fluid or an inflammatory process. The CT scan does not
make that distinction and further diagnostic work-up would be necessary to determine the
etiology of these opacities. The post-treatment image on the right shows resolution of the
ground glass opacities.
Case 7
A 73 year-old man presents with progressive dyspnea on exertion over the past one year.
He reports a dry cough but no wheezes, sputum production, fevers or hemoptysis. He is a
life-long non-smoker and worked as a lawyer until retiring 3 years ago. He likes to hunt
and fish in his leisure time. His pulmonary function testing is as follows:
His pulmonary function tests are shown below:
Test
FVC (L)
FEV1 (L)
FEV1/FVC (%)
FRC
RV (L)
TLC (L)
RV/TLC (%)
DLCO corr
Pre-Bronchodilator (BD)
Actual
Predicted
% Predicted
1.57
4.46
35
1.28
3.39
38
82
76
1.73
3.80
45
1.12
2.59
43
2.70
6.45
42
41
42
5.06
31.64
16
His flow-volume loop is as follows:
Question 7.1
Taking into account his flow-volume loop and pulmonary function tests, what would you
expect to see on plain chest radiography?
A. Flattened diaphragms  incorrect, please try again
B. Bilateral interstitial opacities  correct & explanation
C. Narrow mediastinal contour  incorrect, please try again
D. Large lung volumes  incorrect, please try again
Question 7.1 Explanation
The reduced DLCO, suggests that the restrictive defect is due to an intraparenchymal
process rather than an extraparenchymal process. Choice B the pattern you would expect
to see in idiopathic pulmonary fibrosis, a disease process that typically causes the
pulmonary function test abnormalities seen in this case and the diagnosis this patient was
ultimately found to have. His chest radiographs and images from his Chest CT scans are
shown below. Flattened diaphragms, narrow mediastinal contour and large lung volumes
are all findings that you would see on plain chest radiography in patients with chronic
obstructive pulmonary disease.
PA and Lateral Chest X-Ray
PA and lateral chest radiographs show diffuse reticular markings bilaterally, mostly at the
bases.
Question 7.2
What would be the next appropriate step in this patient’s diagnostic work-up?
A. Cardiopulmonary exercise test  incorrect, please try again
B. Dobutamine stress echocardiography  incorrect, please try again
C. High resolution Chest CT  correct & explanation
D. Bronchoscopy with bronchoalveoloar lavage  incorrect, please try again
E. Open lung biopsy  incorrect, please try again
Question 7.2 Explanation
When patients are found to have a low total lung capacity and reduced DLCO on
pulmonary function testing and the chest radiography findings shown above, suspicion is
raised for interstitial lung disease. The appropriate next diagnostic step would include a
high resolution CT scan of the chest. Depending on the findings on that study, the patient
may or may not be referred for an open lung biopsy. In the hands of a trained
pulmonologist, a typical history in conjunction with classic radiographic findings is
enough to make the diagnosis of idiopathic pulmonary fibrosis, the diagnosis the patient
in this case had. If there are any findings on CT imaging suggestive of an alternative
diagnosis, then bronchoscopy with BAL and/or open lung biopsy will be pursued.
Chest CT Images
Two slices from a high resolution CT scan of the chest showing characteristic findings of
idiopathic pulmonary fibrosis including septal thickening and traction bronchiectasis that
are more prominent in the periphery (sub-pleural regions).
Case 8
A 64 year-old woman presents with complaints of dyspnea and orthopnea. She is a lifelong non-smoker. Her pulmonary function testing is as follows:
Test
FVC (L)
FEV1 (L)
FEV1/FVC (%)
RV (L)
TLC (L)
RV/TLC (%)
DLCO corr
Pre-Bronchodilator (BD)
Actual
Predicted
% Predicted
1.00
2.51
40
0.81
2.00
41
81
80
1.15
1.55
74
2.08
4.04
52
55
39
24.06
30.8
80
Post- BD
Actual
% Change
1.02
3
0.69
13
67
10
Question 8.1
How would you classify the pattern of test results for this patient?
A. Normal spirometry  incorrect, please try again
B. Obstructive pattern  incorrect, please try again
C. Restrictive pattern  correct & explanation
D. Mixed obstructive and restrictive pattern  incorrect, please try again
Question 8.1 Explanation
Her pulmonary function tests are consistent with a restrictive pattern. The FEV1 and FVC
are reduced with a normal FEV1/FVC ratio Her TLC is less than 80% predicted,
confirming the finding of restriction.
Question 8.2
Please grade the severity of her observed defect:
A. Mild  incorrect, please try again
B. Moderate  correct & explanation
C. Severe  incorrect, please try again
D. Very severe  incorrect, please try again
Question 8.2 Explanation
Restriction is graded by the decrement in TLC:
•
•
•
> 65% and < 80% predicted: mild restriction
> 50% and < 65% predicted: moderate restriction
< 50% predicted: severe restriction
In this case, her TLC is 52% predicted which would be labeled as “moderate” in severity.
Question 8.3
Her spirometry is repeated with her in the upright and supine positions:
Test
FVC (L)
FEV1 (L)
FEV1/FVC (%)
Upright
0.49
0.82
0.60
Supine
0.37
0.68
0.54
Which of the following diagnoses could account for the findings on the upright and
supine spirometry and her initial testing shown above?
A.
B.
C.
D.
Pulmonary hypertension  incorrect, please try again
Congestive heart failure  incorrect, please try again
Interstitial lung disease  incorrect, please try again
Diaphragmatic weakness  correct & explanation
Question 8.4 Explanation
This patients pulmonary function testing is most consistent with diaphragmatic weakness.
She has a restrictive process with a preserved DLCO, which suggests that the cause of her
restriction is an extra-parenchymal process such as diaphragmatic paralysis/weakness or
some form of neuromuscular disorder. To help distinguish between these two
possibilities, patients with this pattern of pulmonary function test results will typically
undergo two additional tests: (1) repeat spirometry in the upright and supine positions,
which helps identify diaphragmatic weakness and (2) measurement of maximum
inspiratory and expiratory pressures, which helps identify neuromuscular weakness.
When spirometry is performed in the upright and supine positions, a decrease in the FEV1
and FVC of more than 20%, in the supine position is consistent with diaphragmatic
weakness. These parameters decrease when the patient assumes the supine position
because gravity is no longer available to assist descent of the diaphragm on inspiration.
The weakened diaphragm is unable to push against the abdominal contents. This prevents
the patient from taking a full breath which, therefore, limits the amount of air the patient
can exhale on a forced maneuver. In addition, when the abdominal muscles contract on
exhalation the abdominal contents move in a cephalad direction. Without gravity and in a
weakened state, the diaphragm cannot resist this movement, leading to a decrement in
expiratory volumes.
Case 9
A 35 year-old previously healthy man presents with a 2-month history of dyspnea, fevers,
chills and night sweats. He is a non-smoker with no concerning habits or occupational
exposures. His pulmonary function tests are as follows:
Test
FVC (L)
FEV1 (L)
FEV1/FVC (%)
RV (L)
TLC (L)
RV/TLC (%)
Pre-Bronchodilator (BD)
Actual
Predicted
% Predicted
1.66
4.48
37
0.94
3.67
26
57
82
1.39
1.66
84
3.06
5.96
51
45
29
Question 9.1
How would you classify the pattern of test results for this patient?
A. Normal spirometry  incorrect, please try again
B. Obstructive pattern  incorrect, please try again
C. Restrictive pattern  incorrect, please try again
D. Mixed obstructive and restrictive pattern  correct & explanation
Question 9.1 Explanation
His FEV1 and FVC are both reduced with a reduced FEV1/FVC ratio, indicating the
presence of an obstructive pattern. However, his TLC is also reduced, indicating that he
also has a restrictive defect. This pattern would therefore be labeled as a “mixed
obstructive and restrictive defect.”
Question 9.2
Please grade the severity of the observed abnormality:
A. Mild  incorrect, please try again
B. Moderate  incorrect, please try again
C. Severe  incorrect, please try again
D. Very severe  correct & explanation
Question 9.2 Explanation
The severity of mixed obstructive-restrictive processes is graded by the decrement in the
FEV1:
•
•
•
•
> 80% predicted: mild
> 50% and < 80% predicted: moderate
> 30% and < 50% predicted: severe
< 30% predicted: very severe
His FEV1 is 26% of predicted and, as a result, this would be graded as a very severe
mixed obstructive-restrictive process.
Question 9.3
His flow volume loop is as follows:
This flow-volume loop is most consistent with which of the following findings?
A. No upper airway obstruction  incorrect, please try again
B. Variable intrathoracic upper airway obstruction  incorrect, please try again
C. Variable extrathoracic upper airway obstruction  incorrect, please try again
D. Fixed upper airway obstruction  incorrect, please try again
E. Unilateral mainstem bronchus obstruction  correct & explanation
Question 9.2 Explanation
This patient’s flow-volume loop is consistent with a unilateral mainstem bronchus
obstruction. Note that the expiratory limb has two components – a steep component in
early exhalation and then a flatter component over the latter half of exhalation (see
arrows in the diagram below). This pattern suggests that one lung is emptying faster than
the other.
Steep initial portion
Flattening of the later portion
of the expiratory limb
This patient then underwent a chest radiograph which revealed a dense opacity in the
right chest and shift of the mediastinal contents to the left.
A follow-up CT scan revealed a large mass compressing the right mainstem bronchus
(shown by the black arrow in his CT images below). The mass was so large that it caused
shift of the mediastinal contents to the left side of the chest causing significant restrictive
physiology in the left lung.
Chest CT
Case 10
A 53 year-old woman presents with increasing dyspnea on exertion. She denies cough,
fevers, hemoptysis, weight loss or sweats. She was previously an active runner but has
had to cut back significantly because of the worsening dyspnea. She does note occasional
chest pain with exercise but has not had any syncope or palpitations. Her pulmonary
function tests are as follows:
Pre-Bronchodilator (BD)
Test
Actual
Predicted
% Predicted
FVC (L)
2.38
2.87
83
FEV1 (L)
1.95
2.31
84
FEV1/FVC (%)
82
81
RV (L)
1.69
1.58
107
TLC (L)
4.26
4.36
98
RV/TLC (%)
40
36
DLCO corr
9.96
23.25
43
DLCO is measured in ml/min/mmHg
Post- BD
Actual
% Change
2.23
-6
1.93
-1
87
Question 10.1
Based on the results of this testing, what would be the most appropriate next diagnostic or
therapeutic step for this patient?
A. Start an inhaled corticosteroid  incorrect, try again
B. Start a short-acting inhaled beta-agonist  incorrect, try again
C. Refer for bronchoscopy with bronchoalveolar lavage incorrect, try again
D. Order a High Resolution Chest CT scan  incorrect, try again
E. Order an echocardiogram  correct & explanation
Question 10.1 Explanation
Her FEV1/FVC ratio is above 0.8, her FEV1 and FVC are both above 80% and her TLC is
normal. She therefore has no evidence of obstruction or restriction. She does, however,
have an isolated decrease in her DLCO. An isolated decrease in the DLCO is highly
suggestive of some form of pulmonary vascular disease, such as pulmonary arterial
hypertension and the next most appropriate diagnostic test to work up this issue would,
therefore, be an echocardiogram. Anemia is another process that can result in normal
pulmonary function tests and flow-volume loops with reduced DLCO and this can be ruled
out with appropriate laboratory testing.2
In terms of the other answer choices, the patient does not have any evidence of an
obstructive process that would warrant either inhaled corticosteroids or inhaled
bronchodilators. In the absence of a restrictive process, neither bronchoscopy or a CT
scan would be indicated.
This patient was referred for echocardiography and found to have pulmonary
hypertension. Subsequent work-up revealed that she had chronic thromboembolic
disease as the source of her elevated pulmonary artery pressures.
Question 10.2
How would you characterize the severity of the reduction in her DLCO?
A. Mild  incorrect, try again
B. Moderate  correct & explanation
C. Severe  incorrect, please try again
Question 11.2 Explanation
The severity of abnormalities in DLCO can be characterized as follows2:



Mild: 60% < DLCO < lower limit of normal (lower 5th percentile for reference
population)
Moderate: 50% < DLCO < 64%
Severe: DLCO < 50%
Her DLCO is 43% predicted and, therefore, is considered to be severely decreased.
Case 11
A 36 year-old woman presents with a several month history of worsening dyspnea on
exertion and exercise limitation. She is a life-long non-smoker and has no history of
asthma or other known pulmonary diseases. She had to stop going out with her weekly
running group because she can no longer keep up with her friends. Her pulmonary
function testing is as follows:
Test
FVC (L)
FEV1 (L)
FEV1/FVC (%)
RV (L)
TLC (L)
RV/TLC (%)
DLCO corr
Pre-Bronchodilator (BD)
Actual
Predicted
% Predicted
0.88
3.34
26
0.87
2.87
30
99
86
1.61
1.40
115
2.49
4.73
53
65
29
22
26.6
82
Question 11.1
How would you classify the pattern of test results for this patient?
A. Normal spirometry  incorrect, please try again
B. Obstructive pattern  incorrect, please try again
C. Restrictive pattern  correct & explanation
D. Mixed obstructive and restrictive pattern  incorrect, please try again
Question 11.1 Explanation
Her pulmonary function tests show a restrictive defect. The FEV1 and FVC are reduced
with a preserved FEV1/FVC ratio. The reduced TLC confirms the presence of restriction.
This patient was sent for further pulmonary function testing. She had a 17% drop in her
FVC and a 12% decrease in her FEV1 when testing was performed in the supine position.
Her maximum inspiratory pressures was – 35 cm H20 (normal ~ 100-120 cm H2O) and
her maximum expiratory pressure was - 50 cm H20 (normal ~ 80-100 cm H2O). Her peak
cough flow was 180 L/min (normal > 250 L/min).
Question 11.2
Which of the following diagnoses would be consistent with the pattern of results in her
pulmonary function testing?
A. Neuromuscular weakness  correct & explanation
B. Idiopathic pulmonary fibrosis  incorrect, please try again
C. Pulmonary hypertension  incorrect, please try again
D. Hypersensitivity pneumonitis  incorrect, please try again
E. Diaphragmatic weakness  incorrect, please try again
Question 11.3 Explanation
A restrictive pattern can be seen with neuromuscular weakness, diaphragmatic weakness,
idiopathic pulmonary fibrosis or hypersensitivity pneumonitis. When it occurs in the
absence of parenchymal lung disease, pulmonary hypertension is usually associated with
normal lung volumes and spirometry and an isolated decrease in the DLCO.
This patient has a normal diffusion capacity for carbon monoxide. The preserved
diffusion capacity suggests that her restrictive pattern is probably due to an extraparenchymal process. Of the four choices that can cause a restrictive pattern,
diaphragmatic weakness and neuromuscular disease are two extra-parenchymal processes
that can cause such a pattern.
When patients are found to have a restrictive defect due to an extra-parenchymal process,
two additional sets of tests are indicated:
• Upright and supine spirometry to assess the adequacy of diaphragm function
• Maximum inspiratory and expiratory pressures and a peak cough flow measurement
to assess the adequacy of respiratory muscle strength. (Expiratory flow during cough
is highly dependent on having adequate inspiratory and expiratory muscle strength).
The additional testing performed in her case suggests that of the two likely possible
diagnoses, she most likely has some form of neuromuscular disease. Her FVC and FEV1
both decline by less than 20% when testing was repeated in the supine position, making
diaphragmatic weakness less likely. The maximum inspiratory and expiratory pressures
are reduced below normal, as is her peak cough flow. These results strongly suggest that
she has weak respiratory muscles. She was subsequently referred to a neurologist and
diagnosed with limb girdle muscular dystrophy.
Case 12
A 44 year-old woman with cirrhosis secondary to chronic alcohol abuse and Hepatitis C
presents with complaints of increasing dyspnea. She reports that her dyspnea is worse
when she is sitting upright or walking but improves when she is lying flat. She is an
active cigarette smoker. On exam, her oxygen saturation while breathing air is 88% in the
standing position and 96% in the supine position. Her pulmonary function testing is as
follows.
Test
FVC (L)
FEV1 (L)
FEV1/FVC (%)
RV (L)
TLC (L)
RV/TLC (%)
DLCO corr
Actual
3.94
3.2
82
1.89
5.67
33
10.22
Pre-Bronchodilator (BD)
Predicted
% Predicted
3.69
107%
3.03
105%
82
1.86
102
5.40
105
33
28.22
36
Post- BD
Actual
% Change
3.86
-2
2.85
3
DLCO is measured in ml/min/mmHg
Question 12.1
Which of the following is the most likely diagnosis?
A. Chronic obstructive pulmonary disease  incorrect, try again
B. Hypersensitivity pneumonitis  incorrect, try again
C. Pulmonary vasculitis  incorrect, try again
D. Portopulmonary hypertension  incorrect, try again
E. Hepatopulmonary syndrome  correct & explanation
Question 12.1 Explanation
Her FVC, FEV1, FEV1/FVC, and TLC are normal. Her DLCO is reduced. As discussed in
Case 10, an isolated decrease in the DLCO is suggestive of a pulmonary vascular process.
Of the items on this list, portopulmonary hypertension and hepatopulmonary syndrome
are two pulmonary vascular processes that can be seen in patients with advanced
cirrhosis. The latter is a disorder in which the patients develop small intrapulmonary
shunts, referred to as intrapulmonary vascular dilatations. Both disorders can be
associated with this pattern of results on pulmonary function testing.
Further testing would be needed to confirm the diagnosis but certain features of her
history and initial diagnostic work-up suggest that she has hepatopulmonary syndrome.
She reports that her dyspnea is worse in the upright position, a symptom referred to as
“platypnea”;while her oxygen saturation gets worse in the upright position, a sign
referred to as “orthodeoxia.” These findings are seen in hepatopulmonary syndrome
because the intrapulmonary vascular dilatations that are the hallmark of this disorder are
typically present in the bases of the lungs. When the patients are in the upright position,
more blood flow goes to the lower lung zones and, as a result, they have more shunt
physiology in this position and, as a result, greater dyspnea and lower arterial oxygen
tensions.
The diagnosis of hepatopulmonary syndrome is confirmed by doing an arterial blood gas
shunt study, perfusion scan or contrast echocardiography. A preliminary diagnosis of
portopulmonary syndrome is usually made by measuring pulmonary artery pressures
using echocardiography.
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3. Miller MR, et al. Standardisation of spirometry. Eur Respir J 2005;26:319-338.
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methylphenidate (Ritalin): findings on chest radiographs and CT scans. AJR Am J
Roentgenol 1994;162(3):555-560.
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