Case studies PFT Page 1
RSPT 2325 Diagnostics: PFT Case studies KEY
Name:
Date:
2008
Case study # 1
Your patient is a 45 YO Asian male who presents with episodes of SOB associated with weather
changes and increased activity. On inspection you see a well-developed gentleman in no respiratory
distress, but on auscultation, you note that there are scattered end expiratory wheezes to all
lobes. He has a flatten diaphragm on his chest film and when given .63 mg Levalbuterol in normal
saline by inhalation, he states he feels better.
1.
Are pulmonary function studies indicated for this patient?
Yes, they are indicated after his acute symptoms are under control
2. For which specific indications does he qualify?
We need to discover [1] if he has an obstructive defect or restrictive and [2] if it can
be treated with bronchodilators
3. At this point, do you see any possible contraindications for PFT?
Because bronchospasm can be triggered by the study and because hypoxemia can be
worsened by PFT, we need to treat the acute wheezing and any hypoxemia. We may not
be able to do this PFT for a few days
4. What other data do we need to know about this man to determine his normal values for
pulmonary function studies?
We need his sex, age, BSA race and height to determine his normal lung volumes
5. Which of these bits of data is the most important?
Height is the most important parameter
6. Do you expect his lung volumes and capacities to be decreased?
NO, I don’t expect his slow VC to be decreased, but the FVC might be decreased due
to obstructive defects
7. Do you expect his FRC or his RV to be decreased or increased?
He has air trapping, we might see increased RV which could increase the FRC
8. Do you expect his PEFR to be decreased/ or increased before bronchodilators?
Decreased before
9. Do you expect his FEV1 to be decreased or increased?
Decreased due to decreased exhaled flows, he cannot get rid of the volume in the first
second
Case studies PFT Page 2
After PFT is done, we see the following data:
FVC - 63% predicted
Slow VC - 88% predicted
IC – 89% predicted
FRC- 136% predicted
PEFR – 65% predicted
PIFR 91% predicted
FEV1
62% predicted
FEV1/FVC 67% predicted
FEV 25-75% 65% predicted
MVV – 54% of predicted
10. Do the PFT fit the patient’s physical exam?
 The FVC and slow VC are expected
 The IC should not be decreased in obstructive disorders; so this is no surprise
 With peripheral airway disorders we expect the PEFR to be down ,but not the PIFR
which would reflect a upper airway issue; we would also expect the FEV 25-75% to be
decreased because this average flow in lower airways
 We expect the FEV1 and the FEV1/FRC to be decreased
 We expect the flow volume loop to show normal volumes with decreased expiratory
flows and a scooped out expiratory pattern
11. Why or why not?
Based on the patient’s breath sounds, history and physical exam I suspect this patient has an
acute obstructive defect, and based on his favorable reaction to Beta II drugs, I suspect his
obstructive defect is reversible one such as asthma.
12. Interpret this patient’s Pulmonary function studies in terms of restrictive, mixed or
obstructive defect
This patient has obstructive defect with a degree of air trapping
13. Quantify the derangement as mild, moderate or severe
Moderate to mild
14. Is this disorder reversible? What studies do we need to make this determination?
Because of the patient’s response to inhaled .63 mg Levalbuterol we expect this to be
reversible, but we need to repeat the FVC and the flow volume loop before and after
bronchodilators
Case study # 2
Your patient is a 58 YO LAF who presents with the following s/s. She is in considerable respiratory
distress at rest with RR 25 BPM, HR 109 with sinus tachycardia. Systemic BP is 156/99. She is
afebrile at this time, but has recurrent pneumonias over the last few years. On 12-lead EKG we see
right axis deviation. On auscultation you hear fine inspiratory crackles in upper lobes and decreased
basal breath sounds. This patient gets no relief from inhaled 1.5 mg Albuterol in normal saline.
1.
Are pulmonary function studies indicated for this patient?
Case studies PFT Page 3
 After we have treated her acute distress with supplementary 02
 After we have assess her by X-ray for s/s of CHF and sputum cultures for possible
acute pneumonia
 After we have started appropriate antimicrobial agents for infection or cardiac drugs
for CHF, we might consider PFT—maybe several days later
2. For which specific indications does she qualify?
To determine the presence of restrictive defect and assess her response to
interventions
3. At this point, do you see any possible contraindications for PFT?
She might get hypoxic or suffer hypercapnia during the stress of a PFT
4. Do you expect her lung volumes and capacities to be decreased?
Yes, because of the BBS, I suspect her problem is alveolar so volumes could be down
5. Do you expect her FRC or his RV to be decreased or increased?
decreased
6. Do you expect her PEFR to be decreased/ or increased before bronchodilators?
Not decreased and not changed by bronchodilator
7. Do you expect her FEV1 to be decreased or increased?
Not decreased, unless the FVC is decreased
8. List the two studies done to collect data regarding the RV?
 He dilution studies
 N2 washout
After PFT is done, we see the following data:





FVC - 49% predicted
Slow VC - 49% predicted
IC – 50% predicted
FRC- 45% predicted
PEFR – 88% predicted before
and after BD





PIFR 95% predicted
FEV1
120% predicted
FEV1/FVC 145% predicted
FEV 25-75% 98% predicted
MVV – unable to complete
9. Do the PFT results fit this patient’s physical exam?
yes
10. Why or why not?
 The FVC and slow VC are both down
 The IC and FRC are both down
 There is no problem with PEFR nor PIFR
 The other flows: FEV1, FEV 25-75%
11. Interpret this patient’s Pulmonary function studies in terms of restrictive, mixed or
obstructive defect
 This patient has restrictive defect
12. Quantify the derangement as mild, moderate or severe
 Moderate-severe restrictive defect
Case studies PFT Page 4
13. Are you surprised that this patient was not able to complete the MVV? Do you think this
patient has problems with VT or with RR performing this test?
I would not expect this chronically hypoxic patient to be able to complete the MVV
Because she has a restrictive defect, I expect her to have problems with VT
14. Do you think this patient is at increased risk of hypoxemia during these tests?
Yes, she has cor pulmonale which implies chronic hypoxia
15. Is this disorder reversible?
The PEFR did not change with bronchodilator, so from a PFT stand point this is not
reversible
16. Do you expect this patient to have problems with diffusion of gases? Explain your answer
Yes, because she is hypoxic- which is most likely due to decreased alveolar ventilation
17. What studies would you suggest we order to discover this?
We could study the diffusion of CO, diffusion studies
Case study # 3
Your patient is a 63 YO WF who presents with the following s/s. She is in considerable respiratory
distress at rest with RR 20 BPM, HR 110 with sinus tachycardia. Systemic BP is 145/87. She is
afebrile at this time, but has had 4 episodes of bronchitis over the last two winters. On 12-lead
EKG we see right axis deviation. On auscultation you hear inspiratory crackles, expiratory wheezes
and rhonchi in upper lobes and decreased basal breath sounds. This patient gets some relief from
inhaled 1.25 mg levalbuterol in normal saline.
1.
Are pulmonary function studies indicated for this patient?
Once we stabilize her by treating her increased WOB with supplementary 02 and get her
bronchospasm under control, in a few days we could start monitoring her PFT
2. For which specific indications does she qualify?
Assess her for the presence of restrictive disorders, differentiate between restrictive
and obstructive defect and monitor the effect of interventions on her
3. At this point, do you see any possible contraindications for PFT?
Not once we get her stable; but she may need supplementary 02 during the test because
her cor pulmonale implies she has chronic hypoxemia
4. Do you expect her lung volumes and capacities to be decreased?
Yes because of the inspiratory crackles
5. Do you expect her FRC or his RV to be decreased or increased?
Increased, if there is air trapping
6. Do you expect her PEFR to be decreased/ or increased before bronchodilators?
Decreased if there is bronchospasm & to increase after BD because she had good
response to the drug
7. Do you expect her FEV1 to be decreased or increased?
Decreased due to wheezing
After PFT is done, we see the following data:
Case studies PFT Page 5






FVC - 75% predicted
Slow VC - 80% predicted
IC – 82% predicted
FRC- 95% predicted
PEFR – 75% predicted before BD
PEFR 74% after BD





PIFR 72% predicted
FEV1
70% predicted
FEV1/FVC 75% predicted
FEV 25-75% 73% predicted
MVV – 63% predicted
18. Do the PFT results fit this patient’s physical exam?
Yes and no
Why or why not?
I expected both bronchospasm with low flows and restrictive defects with low volumes, but
I see that the volumes aren’t all that low. I did not expect the PIFR to be decreased
19. Interpret this patient’s Pulmonary function studies in terms of restrictive, mixed or
obstructive defect
 The FVC is decreased, while the slow VC is not- obstructive
 The other volumes and capacities are WNL
 The PERF is decreased and not responsive to bronchodilator - obstructive
 The PIFR is decreased which may imply an obstructive central airway issue
 FEV1 and FEV1/FVC are both decreased- obstruction
 There is small airway obstruction
20. Quantify the derangement as mild, moderate or severe
Mild obstructive defect that did not respond well to bronchodilator
21. What problems can this flow volume loop indication?
This patient may have a intra-thoracic large airway obstruction such as compression on
the central airways or a tumor in the airway
22. Is this disorder reversible?
The PEFR was not affected by bronchodilator, but the central airway obstruction might
be causing the PEFR to not change
Case study #4
Your patient is a 55 YO WM who is getting PFT to assess his recent onset of moderate hypoxemia.
He had a forced vital capacity and flow volume loops measured, but we need his residual volume.
This patient has a FVC of 3.9 Liters, and IC of 2.5 Liters.
1.
List two ways this RV can be measured by gas dilution and one other method.

He dilution and N2 washout

Body box
2. The patient underwent Helium dilution. How does this work?
The patient has a know volume of gas in the circuit, a know volume and percentage of He
gas in the circuit. He has an unknown volume of gas in the lungs. As he breaths, the He
diffusions throughout the circuit and the patient’s lungs.
At the end we compare the final He percentage to calculate the unknown volume in his
lung.
Case studies PFT Page 6
From this TLC we can calculate the FRC [because we already had the VC of the simple
spirometry] and the RV. At this point we can document the air trapping
3. Identify the function of the canister of soda lime found in the circuit.
The soda lime will absorb the exhaled C02 that builds up in the circuit
4. Based on the Helium dilution, the TLC was found to be 5.1 liters. Calculate the patient FRC from
this .
The patient has an FVC of 3.9 Liters, and IC of 2.5 Liters, so if the TLC is 5.1 liters we can
subtract the IC from the TLC to get the FRC: 5.1-3.9 = 1.2 liters
5. Calculate the patient’s RV from this.
The patient has an FVC of 3.9 Liters, and IC of 2.5 Liters, so if the TLC is 5.1 liters we can
subtract the FVC from the TLC to get the RV: 5.1 – 3.9 = 1.2 liters RV
6. If we had done an open-circuit measurement, what gas would we have used?
We would give 100% to blow off the N2
7. After the patient’s lung volumes and flows were measured and found to be +/- 20% predicted,
we must measure the gas diffusion.
8. What PFT test measures gas diffusion?

DLC0 measures the diffusion of CO from this we can extrapolate the diffusion
of 02.
9. Identify the gas used in this measurement and explain why it was selected

We use CO because this gas will load up on the Hb and not get into the plasm. The
gradient of alveolar-arterial CO is = to the alveolar CO because the arterial CO is
zero
10. The resulting DLCO is 11.5 ml/min/mmHg. Is this in the normal limits?

No, it is decreased--Normal is 20-30 ml/min/mmHg
11. Calculate the DLO2

DLCO [1.23] = DLO2

11.5 [1.23] = 14.145
12. Discuss the clinical significance of this patient’s poor gas perfusion in the face of normal lung
volumes and normal exhaled flows.
We expect a little diffusion problems with restrictive or obstructive defects that result in
hypoxemia, but when there is no problem with alveolar ventilation we need to worry about
diffusion defects such as pulmonary emboli or more rarely pulmonary vascular edema