Illustrative Cases
The cases presented in this chapter demonstrate many of the points made in the preceding text. A few examples are of unusual cases, but most present problems that are commonly evaluated in the pulmonary function laboratory.
For most of the cases, the flow-volume curve should be studied first. After a preliminary interpretation is reached, the measurements should be reviewed to determine whether they support or change this interpretation. Frequently, some questions are posed, and an attempt should be made to answer them before the answers are read. (The cases are not arranged in a particular order). In the tables, the normal predicted value, observed value, and the percentage of the predicted value are listed. Abnormal values that are less or more than the normal range are indicated by an asterisk (*). The equations used to predict these values are given in the Appendix. The types of cases are listed on pages 220 and 221. In addition, the abbreviations used in the chapter are defined at the front of the book.
Case 1
|
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Comments and Questions
This patient had a smoking history of 74 pack-years and was still smoking. He complained of progressive breathlessness and wheezing on mild exertion. He had a family history of pulmonary disease.
2. Can you make a statement as to the patient’s underlying lung disease?
View Answer
2. If only the results of spirometry were available, it could be said that “there is severe ventilatory limitation on an obstructive basis, but a small restrictive component cannot be ruled out without a measurement of total lung capacity.” Of course, if a chest radiograph showed hyperinflation, then it is almost certain that the abnormalities were all obstructive.
3. Does the DLCO suggest anything?
View Answer
3. In this case with the hyperinflation and obstruction, the low DLCO is consistent with anatomic emphysema, and high-resolution computed tomography would be expected to confirm this. InCase 10 (page 146), in which the TLC is very low and the slope of the flow-volume curve is steep, the low DLCO probably reflects the presence of some type of fibrosis. Often when the DLCO is low, however, only a general statement can be made, such as “the low DLCO suggests the presence of a parenchymal or vascular abnormality.”
Case 1
Answers
1. The patient has severe ventilatory limitation on an obstructive basis. Significant hyperinflation is present with an increased TLC and RV/TLC ratio. There is a considerable response to bronchodilator.
2. If only the results of spirometry were available, it could be said that “there is severe ventilatory limitation on an obstructive basis, but a small restrictive component cannot be ruled out without a measurement of total lung capacity.” Of course, if a chest radiograph showed hyperinflation, then it is almost certain that the abnormalities were all obstructive.
3. In this case with the hyperinflation and obstruction, the low DLCO is consistent with anatomic emphysema, and high-resolution computed tomography would be expected to confirm this. InCase 10 (page 146), in which the TLC is very low and the slope of the flow-volume curve is steep, the low DLCO probably reflects the presence of some type of fibrosis. Often when the DLCO is low, however, only a general statement can be made, such as “the low DLCO suggests the presence of a parenchymal or vascular abnormality.”
Case 2
|
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Questions
3. Is the configuration of the flow-volume curve normal?
View Answer
3. Over most of the vital capacity, flow decreases in a relatively gradual, steady fashion. However, at 2.4 L of expired volume, there is a “knee” in the curve after which flow decreases rapidly. This contour is not due to a major airway lesion but is a normal variant that is often found in nonsmokers, especially women. This patient had never smoked. This curve shape is due to the point of critical narrowing staying in the trachea until the “knee” is reached (see Fig. 2-6H). After this point, flow is limited in the peripheral airways. This is called a tracheal plateau.
Case 2
Answers
1. There is no ventilatory limitation.
2. The test values are all normal.
3. Over most of the vital capacity, flow decreases in a relatively gradual, steady fashion. However, at 2.4 L of expired volume, there is a “knee” in the curve after which flow decreases rapidly. This contour is not due to a major airway lesion but is a normal variant that is often found in nonsmokers, especially women. This patient had never smoked. This curve shape is due to the point of critical narrowing staying in the trachea until the “knee” is reached (see Fig. 2-6H). After this point, flow is limited in the peripheral airways. This is called a tracheal plateau.
Case 3
|
| |||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Questions
1. Is there any ventilatory limitation?
View Answer
1. The control flow-volume curve shows some loss of area, consistent with a mild ventilatory limitation.
3. Is there anything unique about this patient?
4. The patient had been a light smoker since age 20 years, smoking an average of eight cigarettes a day, or 3.6 pack-years. She reported episodes of bronchitis with wheezing and breathlessness. Is there any other test you would order?
View Answer
4. On the basis of the history, a methacholine challenge test is a reasonable procedure to order because many patients with asthma are diagnosed as having bronchitis.
Case 3
Answers
1. The control flow-volume curve shows some loss of area, consistent with a mild ventilatory limitation.
2. The low but normal TLC, the proportionate reduction in FVC and FEV1, the normal FEV1/FVC ratio, and the normal DLCO indicate the presence of a nonspecific pattern (seeSection 3E).
3. The patient is obese; the BMI is 47.4 kg/m2 (normal, <25).
4. On the basis of the history, a methacholine challenge test is a reasonable procedure to order because many patients with asthma are diagnosed as having bronchitis.
|
As shown in the figure, the patient has hyperreactive airways with a markedly reduced flow-volume curve after methacholine. The FEV1 decreased by 21%.
The diagnosis now becomes “mild ventilatory limitation due to asthma and probably obesity.”
Case 4
|
|
Questions
1. What is your estimate of the degree of limitation?
2. What is causing the limitation?
4. Is there anything unusual about the flow-volume curve?
View Answer
4. There is something unusual about the flow-volume curve; namely, there is a plateau in flow at about 1.3 L/s over the upper 50% of the FVC that is abnormal. It is characteristic of a major airway lesion.
5. Is there any other test that you would order?
View Answer
5. The test that should be ordered is an inspiratory flow-volume loop. The expiratory curve and the corresponding inspiratory loop are reproduced in the figure below as the solid lines. The nearly equal reduction in maximal expiratory and inspiratory flows points to a relatively fixed airway lesion.
Case 4
Answers
1. There is a moderate degree of expiratory flow limitation.
2. On the basis of the test data, the limitation is obstructive.
3. The decrease in the MVV to 27% predicted is greater than might be expected from an FEV1 of 47% predicted. This finding should suggest poor patient effort, a neuromuscular process, or a major airway lesion. In this case, the technicians thought the patient gave a good effort.
4. There is something unusual about the flow-volume curve; namely, there is a plateau in flow at about 1.3 L/s over the upper 50% of the FVC that is abnormal. It is characteristic of a major airway lesion.
5. The test that should be ordered is an inspiratory flow-volume loop. The expiratory curve and the corresponding inspiratory loop are reproduced in the figure below as the solid lines. The nearly equal reduction in maximal expiratory and inspiratory flows points to a relatively fixed airway lesion.
|
The patient was found to have Wegener granulomatosis (also called granulomatosis with polyangiitis). Bronchoscopy showed narrowing of both main stem bronchi and of several lobar bronchi. Ordinarily, single obstructing lesions below the carina cannot be detected with certainty. However, because both main stem bronchi were involved, a characteristic abnormality in the flow-volume loop could be detected.
With the patient under general anesthesia, the left main stem bronchus and bronchus intermedius were dilated, and stents were placed in both. The right main stem bronchus was also dilated. The dashed flow-volume loop in the figure above was obtained 1 month after this procedure, and although the flows are not normal, they are much improved.
Case 5
|
|
Comments
This 52-year-old woman complained of chronic cough and mild dyspnea on exertion. She had never smoked. She was heavy for her height; the BMI is 36.7 kg/m2.
The control flow-volume curve in the figure is normal and typical of a nonsmoker. Spirometry data are also normal, but the flow-volume curve shows increased curvature over the lower 50% of the FVC, suggesting mild airway obstruction.
The patient underwent a methacholine challenge study, and the FEV1 decreased to 14%, which is a negative test result. The post-challenge curve, selected because it had the largest FEV1, is shown in the first figure.
The peak expiratory flow of the effort in the first figure is 4.5 L/s. Another post-challenge effort with a peak expiratory flow of 5.6 L/s was obtained, as shown below. This curve is curvilinear, consistent with airway obstruction. Because of the better effort reflected in the higher peak flow, this curve should have been selected. Its FEV1 is 1.88 L, showing a 23% decrease and hence a positive result of methacholine challenge. This example confirms the statement inSection 5D, namely, that a slightly submaximal effort can lead to an overestimation of the FEV1, especially when there is airway obstruction.
|
Case 6
|
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Comments
This 51-year-old woman had active rheumatoid arthritis and was receiving low-dose prednisone. She had never smoked. Because of a history of an allergic reaction to a medication that produced mild dyspnea and cough, a methacholine challenge test was ordered.
The control study fits our definition of mild nonspecific pattern (seeSection 3E); that is, the TLC is within normal limits, the FEV1 and FVC are both abnormally low, and the FEV1/FVC ratio is normal. The normal DLCO does not suggest any parenchymal problem, such as fibrosis, even though the flow-volume curve is rather steep. The patient is heavy for height; the BMI is 32.4 kg/m2.
Despite the normal FEV1/FVC ratio, the patient has hyperreactive airways with a 21% decrease in the FEV1 associated with cough and some chest tightness. Thus, in this patient a nonspecific pattern is obscuring a mild case of asthma. There is a hint of increased curvature of the control flow-volume plot low in the vital capacity, but this is very subtle.
Case 7
|
| |||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Comments and Questions
The patient is a nonsmoker and complains of shortness of breath at times while hurrying on a level surface. On occasion she has noted some wheezing.
1. Does the patient have ventilatory limitation? If so, on what basis?
View Answer
1. The patient does have mild ventilatory limitation. This appears to be due to equal reductions in the FEV1 and FVC and thus a normal ratio. The lownormal TLC suggests a possible mild restrictive defect, as does the initial steep slope of the flow-volume curve. In addition, however, the increased curvature of the flow-volume curve raises the possibility of a mild airway obstruction. Thus, the limitation is likely due to a mixed restrictive-obstructive process.
3. Is there any additional study you would want?
View Answer
3. With a history of wheezing in a nonsmoker, a methacholine challenge study is in order. The figure below shows a markedly positive result of methacholine challenge with a 41% decrease in the FEV1. Despite this, the FEV1/FVC ratio stayed in the high-normal range. The patient experienced some dyspnea, which was promptly relieved by an inhaled bronchodilator.
Case 7
Answers
1. The patient does have mild ventilatory limitation. This appears to be due to equal reductions in the FEV1 and FVC and thus a normal ratio. The lownormal TLC suggests a possible mild restrictive defect, as does the initial steep slope of the flow-volume curve. In addition, however, the increased curvature of the flow-volume curve raises the possibility of a mild airway obstruction. Thus, the limitation is likely due to a mixed restrictive-obstructive process.
2. The patient is heavy for her height; the BMI is 34.3 kg/m2. This may contribute to the reduced FVC and low TLC.
3. With a history of wheezing in a nonsmoker, a methacholine challenge study is in order. The figure below shows a markedly positive result of methacholine challenge with a 41% decrease in the FEV1. Despite this, the FEV1/FVC ratio stayed in the high-normal range. The patient experienced some dyspnea, which was promptly relieved by an inhaled bronchodilator.
|
Case 8
|
| |||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Comments and Questions
The inspiratory loop was obtained after a slow expiration to residual volume. This SVC was used to compute the RV/TLC ratio. This 43-year-old woman with a 16 pack-year smoking history had the recent onset of chest discomfort, shortness of breath, and wheezing after a viral-like illness, 3 weeks before this study.
1. What features of the control flow-volume loop are unusual?
View Answer
1. The striking features of the control flow-volume loop are as follows:
a. The marked reduction in expiratory flows with reasonably normal inspiratory flows—variable intrathoracic lesion
b. The marked difference between the expiratory FVC (1.2 L) and the inspiratory vital capacity (4.0 L)
2. Are any features of the function data unusual?
View Answer
2. The spirometric values are typical of severe obstruction. The only possible unusual finding is the normal DLCO with this degree of obstruction, but this situation can occur.
3. What might be the patient’s problem?
View Answer
3. The sudden onset of this degree of obstruction and the marked difference in the inspiratory and expiratory flows and volumes suggest a major airway lesion.
4. Is there a procedure you might request?
Case 8
Answers
1. The striking features of the control flow-volume loop are as follows:
a. The marked reduction in expiratory flows with reasonably normal inspiratory flows—variable intrathoracic lesion
b. The marked difference between the expiratory FVC (1.2 L) and the inspiratory vital capacity (4.0 L)
2. The spirometric values are typical of severe obstruction. The only possible unusual finding is the normal DLCO with this degree of obstruction, but this situation can occur.
3. The sudden onset of this degree of obstruction and the marked difference in the inspiratory and expiratory flows and volumes suggest a major airway lesion.
4. The appropriate procedure would be chest radiography or CT followed by bronchoscopy.
The patient had an abnormal chest radiograph with hilar enlargement, and bronchoscopy revealed a large lesion almost occluding the intrathoracic trachea (A). The squamous cell lesion was managed initially with laser therapy; the symptoms and the second flow-volume loop improved (B). Thoracic radiation and chemotherapy led to disappearance of the tumor, and the third flow-volume loop was normal.
|
Case 9
|
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Comments and Questions
This 67-year-old man had a history of 59 pack-years of smoking. He had complained 5 years previously of shortness of breath while walking on a level surface. His dyspnea, often accompanied by wheezing, had become progressively worse, to the point that he had to stop walking after one block.
1. How would you describe the flow-volume curve?
View Answer
1. There is a considerable loss of area under the flow-volume curve, and the curve is typical of obstruction. Thus, “severe ventilatory limitation secondary to airway obstruction” would be correct.
2. Do the test results support your impression? (Incidentally, the postdilator flow-volume curve is not shown for the sake of clarity, but it did show a positive response with higher flows and volumes.)
Case 9
Answers
1. There is a considerable loss of area under the flow-volume curve, and the curve is typical of obstruction. Thus, “severe ventilatory limitation secondary to airway obstruction” would be correct.
2. The increased TLC and RV are consistent with this interpretation, as are the markedly reduced FEV1 and forced expiratory flow rate over the middle 50% of the FVC (FEF25-75).
The DLCO is in the low-normal range, which argues against significant anatomic emphysema. This is a good example of a patient with chronic bronchitis who responds to a bronchodilator and has desaturation with exercise. Not shown was the oximetry result—a resting oxygen saturation of 94% that decreased to 86% with mild exercise.
Case 10
|
| |||||||||||||||||||||||||||||||||||||||||||||||||||||||
Questions
2. Do the data confirm your initial impression?
View Answer
2. The extremely low TLC supports a restrictive process as the cause of the limitation. In addition, the markedly reduced DLCO suggests disease of the lung parenchyma. Indeed, this man had severe interstitial fibrosis of unknown cause. He also had cor pulmonale. His oxygen saturation at rest was 95%, and it decreased to 85% with mild stair climbing.
3. Could obesity or a severe chest wall deformity produce these results?
View Answer
3. Although extreme obesity can reduce the TLC, it probably never does it to this extent. In addition, a normal to increased DLCO might be expected in obesity. A severe chest deformity should not be associated with this degree of reduction in the DLCO. Furthermore, the steep slope of the flow-volume curve is very unlikely with either extreme obesity or chest wall deformity.
Case 10
Answers
1. The initial impression is of very severe ventilatory limitation on a restrictive basis because of the marked decreases in the TLC and FVC and the steep slope of the flow-volume curve (roughly [[7 L/s]/L]). In addition, the FEV1/FVC ratio is high.
2. The extremely low TLC supports a restrictive process as the cause of the limitation. In addition, the markedly reduced DLCO suggests disease of the lung parenchyma. Indeed, this man had severe interstitial fibrosis of unknown cause. He also had cor pulmonale. His oxygen saturation at rest was 95%, and it decreased to 85% with mild stair climbing.
3. Although extreme obesity can reduce the TLC, it probably never does it to this extent. In addition, a normal to increased DLCO might be expected in obesity. A severe chest deformity should not be associated with this degree of reduction in the DLCO. Furthermore, the steep slope of the flow-volume curve is very unlikely with either extreme obesity or chest wall deformity.
Case 11
|
| |||||||||||||||||||||||||||||||||||||||||||||||||||||||
Questions
1. This 68-year-old man had recently noted becoming quite short of breath when first lying down. Because this then decreased, he was able to sleep at night. He denied any significant dyspnea while walking or climbing stairs. He had been a heavy smoker but quit 15 years ago. What is your initial impression of the flow-volume curve?
View Answer
1. Certainly the flow-volume curve suggests a moderate ventilatory limitation that, on the basis of the contour of the curve, appears to be obstructive in nature.
2. Do the test results agree with your initial assessment?
View Answer
2. The test results do not totally support the stated diagnosis. There is some airflow obstruction, indicated best by the reduced FEF25-75. However, the reduction in the TLC is not consistent with pure obstruction, nor is the normal FEV1/FVC ratio. The patient’s BMI of 28.9 kg/m2 is not sufficient to explain the restrictive component as being due to obesity.
3. Are there any other tests you might order?
View Answer
3. The history suggested to the clinician that the patient might have bilateral diaphragmatic paralysis. The physician ordered fluoroscopy, which showed paralyzed diaphragms. The physician also ordered a supine flow-volume curve. Note the marked reduction of the second flow-volume curve obtained in the supine posture.
Case 11
Answers
1. Certainly the flow-volume curve suggests a moderate ventilatory limitation that, on the basis of the contour of the curve, appears to be obstructive in nature.
2. The test results do not totally support the stated diagnosis. There is some airflow obstruction, indicated best by the reduced FEF25-75. However, the reduction in the TLC is not consistent with pure obstruction, nor is the normal FEV1/FVC ratio. The patient’s BMI of 28.9 kg/m2 is not sufficient to explain the restrictive component as being due to obesity.
3. The history suggested to the clinician that the patient might have bilateral diaphragmatic paralysis. The physician ordered fluoroscopy, which showed paralyzed diaphragms. The physician also ordered a supine flow-volume curve. Note the marked reduction of the second flow-volume curve obtained in the supine posture.
|
The physician also ordered maximal respiratory pressure measurements:
PEmax was 215 cm H2O (normal, 200)
PImax was -36 cm H2O (normal, -103)
These data are consistent with almost complete paralysis of the diaphragm. In summary, this was a limitation due to a mixed restrictive-obstructive process. The restrictive process dominated and was due to idiopathic diaphragmatic paralysis.
Case 12
|
| |||||||||||||||||||||||||||||||||||||||||||||||||||||||
Comments and Questions
The patient complained of dyspnea climbing one flight of stairs. She had never smoked. She had some joint stiffness and pain.
1. What does the flow-volume curve suggest?
View Answer
1. The lost area under the normal curve suggests mild ventilatory limitation. The rather steep slope of the flow-volume curve suggests either a restrictive process or a nonspecific process, depending on the TLC.
View Answer
2. The mild reduction in the TLC does not quite qualify as a restrictive pattern, but it should raise your suspicion. The best interpretation is that of a mild nonspecific ventilatory limitation associated with a reduced diffusing capacity.
Case 12
Answers
1. The lost area under the normal curve suggests mild ventilatory limitation. The rather steep slope of the flow-volume curve suggests either a restrictive process or a nonspecific process, depending on the TLC.
2. The mild reduction in the TLC does not quite qualify as a restrictive pattern, but it should raise your suspicion. The best interpretation is that of a mild nonspecific ventilatory limitation associated with a reduced diffusing capacity.
The patient has scleroderma with minimal interstitial fibrosis shown by radiography, which explains the reduced DLCO and probably the steep slope of the flow-volume curve. The fibrosis and the chest skin changes of scleroderma are reducing the TLC.
Case 13
|
| |||||||||||||||||||||||||||||||||||||||||||||||||||||||
Stay updated, free articles. Join our Telegram channel
Full access? Get Clinical Tree
