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 rEV1ewed 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 247 and 248. Also, the abbrEV1ations used in the chapter are defined on pages xi-xiii.
CASE 1
71 y M Wt 195 lb (88 kg) Ht 69 in. (175 cm) BMI 28.7 kg/m2
|
Normal |
Observed |
% predicted |
Post-dilator |
|
|
Spirometry |
||||
|
FVC (L) |
4.29 |
1.94* |
45 |
2.76 |
|
FEV1 (L) FEV1/FVC (%) |
3.29 77 |
1.03* 53* |
31 |
1.25 |
|
FEF25-75 (L/s) |
2.8 |
0.4* |
15 |
0.5 |
|
MVV (L/min) |
125 |
51* |
41 |
|
|
Volumes |
||||
|
TLC (L) |
6.61 |
9.37* |
142 |
|
|
RV/TLC(%) |
35 |
75* |
214 |
|
|
Dlco (mL/min per mm Hg) |
25 |
10* |
40 |
|
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.
1. How would you interpret this test?
2. Can you make a statement as to the patient's underlying lung disease?
3. Does the reduced Dlco suggest anything?
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. The reduced diffusing capacity suggests the presence of anatomic emphysema.
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. In case 10 (page 173), 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 Dlcosuggests the presence of a parenchymal or vascular abnormality.''
CASE 2
Questions
1. Does the patient have ventilatory limitation?
2. Do the test values support your impression?
3. Is the configuration of the flow-volume curve normal?
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, page 16). This is called a tracheal plateau.
CASE 3
29 y F Wt 284 lb (129 kg) Ht 65 in. (165 cm) BMI 47.4 kg/m2
Questions
1. Is there any ventilatory limitation?
2. On the basis of the given data, what diagnosis would you give?
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?
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 ''nonspecific ventilatory limitation'' (see section 3E, page 36).
3. The patient is obese; the BMI is 47.4 kg/m2 (normal, <30).
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 21%.
The diagnosis now becomes ''mild ventilatory limitation due to asthma and probably obesity.''
CASE 4
76 y M Wt 170 lb (77 kg) Ht 66 in. (168 cm) BMI27.3kg/m2
Questions
1. What is your estimate of the degree of limitation?
2. What is causing the limitation?
3. Is there anything unusual about the test data?
4. Is there anything unusual about the flow-volume curve?
5. Is there any other test that you would order?
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's granulomatosis. 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
52 y F Wt 207 lb (94 kg) Ht 63 in. (160 cm) BMI 36.7 kg/m2
|
Spirometry |
Normal |
Observed |
% predicted |
Post-challenge |
|
FVC (L) |
3.17 |
3.37 |
106 |
|
|
FEV1 (L) |
2.61 |
2.45 |
94 |
2.10 (-14%) |
|
FEV1/FVC (%) |
83 |
73 |
||
|
FEF25 - 75 (L/s) |
2.6 |
1.7 |
67 |
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 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 in section 5D (page 53), namely, that a slightly submaximal effort can lead to an overestimation of the FEV1, especially when there is airway obstruction.
CASE 6
51 y F Wt 182 lb (83 kg) Ht 63 in. (160 cm) BMI 32.4 kg/m2
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 fit our definition of mild ''nonspecific ventilatory limitation'' (see section 3E, page 36); 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
67 y F Wt 198 lb (90 kg) Ht 64 in. (162 cm) BMI 34.3 kg/m2
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?
2. Is there anything unusual about the patient?
3. Is there any additional study you would want?
CASE 7
Answers
1. The patient does have mild ventilatory limitation. This appears to be nonspecific, with equal reduction in the FEV1 and FVC and thus a normal ratio. The low-normal 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 metha- choline 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.
In summary, this is another case of asthma in an obese subject in whom the FEV1/FVC ratio was high-normal on presentation. Usually, this finding does not suggest airway obstruction. Also, the low-normal TLC does not suggest obstruction; however, in this case it may be due to obesity.
CASE 8
43 y F Wt 134 lb (61 kg) Ht 66 in. (168 cm) BMI 21.6 kg/m2
|
Normal |
Observed |
% predicted |
|
|
Spirometry |
|||
|
FVC (L) |
3.71 |
1.22* |
33 |
|
FEV1 (L) |
3.05 |
0.51* |
17 |
|
FEV1/FVC (%) |
82 |
42* |
|
|
FEF25-75 (L/s) |
2.8 |
0.1* |
|
|
MVV (L/min) |
111 |
40* |
36 |
|
Volumes |
|||
|
TLC (L) |
5.34 |
6.07 |
114 |
|
RV/TLC (%) |
31 |
32 |
103 |
|
Dlco (mL/min per mm Hg) |
24 |
23 |
96 |
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?
2. Are any features of the function data unusual?
3. What might be the patient's problem?
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 possibly 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 bronchoscopy.
The patient had an abnormal chest radiograph with hilar enlargement, and bronchoscopy revealed a large lesion almost occluding the intrathoracic trachea. The squamous cell lesion was managed initially with laser therapy; the symptoms and the second flow-volume loop improved. Thoracic radiation and chemotherapy led to disappearance of the tumor, and the third flow-volume loop was normal.
CASE 9
67 y M Wt 189 lb (86 kg) Ht 71 in. (180 cm) BMI 26.5 kg/m2
|
Normal |
Observed |
% predicted |
Post-dilator |
|
|
Spirometry |
||||
|
FVC (L) |
4.79 |
2.06* |
43 |
2.67 |
|
FEV1 (L) FEV1/FVC (%) |
3.67 77 |
0.56* 27* |
15 |
0.75 |
|
FEF25-75 (L/s) |
31 |
0.2* |
6 |
|
|
MVV (L/min) |
136 |
29* |
21 |
|
|
Volumes |
||||
|
TLC (L) |
7.02 |
8.64* |
123 |
|
|
RV/TLC(%) |
32 |
69* |
216 |
|
|
Dlco (mL/min per mm Hg) |
27 |
21 |
79 |
|
Comments and Questions
This 67-year-old man had a history of 59 pack-years of smoking. He had complained 5 years prEV1ously 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?
2. Do the test results support your impression? (Incidentally, the post-dilator 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 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
30 y M Wt 151 lb (68 kg) Ht 73 in. (186 cm) BMI 19.7 kg/m2
Questions
1. What is your initial impression of the flow-volume curve?
2. Do the data confirm your initial impression?
3. Could obesity or a severe chest wall deformity produce these results?
CASE 10
Answers
1. The initial impression is of very severe ventilatory limitation on a restrictive basis because of the marked decrease in the FVC and the steep slope of the flow-volume curve
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. Also, 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
68 y M Wt 224 lb (102 kg) Ht 74 in. (188 cm) BMI 28.9 kg/m2
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?
2. Do the test results agree with your initial assessment?
3. Are there any other tests you might order?
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. He ordered fluoroscopy, which showed paralyzed diaphragms. He 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
Volume (L)
49 y F Wt 158 lb (72 kg) Ht 66 in. (168 cm) BMI 25.5 kg/m2
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?
2. Considering the test results, what is your final interpretation? (Note that during the past 3 years the TLC, FVC, and Dlco have gradually declined.)
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 for a restrictive dysfunction, 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
39 y M Wt 170 lb (77 kg) Arm span 79 in. (200 cm) BMI 19.3 kg/m2
|
Normal |
Observed |
% predicted |
|
|
Spirometry |
|||
|
FVC (L) |
6.32 |
2.37* |
38 |
|
FEV1 (L) |
5 |
1.94* |
39 |
|
FEV1/FVC (%) |
79 |
82 |
|
|
FEF25-75 (L/s) |
4.4 |
1.7* |
38 |
|
MVV (L/min) |
186 |
121* |
65 |
|
Volumes |
|||
|
TLC (L) |
7.94 |
3.62* |
46 |
|
RV/TLC (%) |
20 |
33 |
165 |
|
Dlco (mL/min per mm Hg) |
39 |
19* |
50 |
Questions
1. How do you classify the flow-volume curve?
2. What is your interpretation after rEV1ewing the test results?
3. What is the diagnosis?
CASE 13
Answers
1. The flow-volume curve can be described as showing severe ventilatory limitation, and the slope of the curve suggests a restrictive component.
2. The reduced TLC confirms the presence of a restrictive defect. In addition, the reduced Dlco suggests a parenchymal abnormality. Therefore, this is a severe ventilatory limitation on the basis of a restrictive process with an impaired diffusing capacity suggesting a parenchymal abnormality.
3. Note that the patient's arm span was used to predict his normal values. The patient has severe idiopathic scoliosis with areas of compressed lung. Use of the measured height would have underestimated the severity of his problem, as seen below.
The flow-volume curve below shows the patient's curve plotted against the predicted curve for his actual height of 167.6 cm. Now the FVC is 54% of predicted versus 38%, and the FEV1 shows a similar difference.
This is a complex case. The main point is that the technicians must measure the arm span and use it to predict the normal values in all subjects with spinal deformities.
CASE 14
22 y F Wt 117 lb (53 kg) Ht 60 in. (152 cm) BMI 22.9 kg/m2
Comments and Questions
This 22-year-old woman was seen for a lump in her throat that interfered with swallowing and for anxiety. She noted in passing that sometimes she became short of breath, but she denied wheezing. Results of physical examination were negative. 1 2
1. How would you interpret the flow-volume curve and test data?
2. Is there any other procedure you would order?
CASE 14
Answers
1. On the basis of the area loss at lower volumes, the low- normal TLC, the proportional reduction in FVC and FEV1 resulting in a normal ratio, the lack of a dilator response, and the normal Dlco, this test fits the ''nonspecific ventilatory limitation'' category. Airway resistance was measured and was normal.
2. Because the results of cardiac examination were normal and the cause of her dyspnea was unknown, a methacholine challenge test was ordered. The curve after five breaths of methacholine is shown below. There was a 35% decrease in the FEV1 associated with chest tightness and dyspnea similar to what the patient had been experiencing.
An interesting feature is the parallel shift in the post- methacholine curve resulting in an FEV1/FVC ratio that was 90% despite the severe bronchoconstriction. Also, the measurement of airway resistance during the initial part of the study failed to detect any abnormality. The slightly increased slope
of the control curve and the low-normal TLC might raise the question of mild pulmonary fibrosis but, of course, the normal Dlco argues against this. In fact, this is an example of occult asthma characterized mainly by a decrease in the FEV1 and FVC and some increase in the slope of the flow-volume curve, that is, a nonspecific abnormality.
CASE 15
64 y F Wt 377 lb (171 kg) Ht 65 in. (165 cm) BMI 62.8 kg/m2
Question
1. How would you interpret this test?
CASE 15
Answer
1. The contour of the flow-volume curve suggests borderline airway obstruction. Measurement of TLC would be needed to determine whether a restrictive component is present. The patient's excessive weight for her height may be playing a role in the mild limitation.
This case illustrates that even in an elderly nonsmoker, morbid obesity (the BMI is 62.8 kg/m2) may have only a mild effect on pulmonary function. Of course, this is not always the case.
CASE 16
17 y M Wt 170 lb (77 kg) Ht 69 in. (175 cm) BMI 25.1 kg/m2
|
Normal |
Observed |
% predicted |
Post-challenge |
% change |
|
|
Spirometry |
|||||
|
FVC (L) |
4.67 |
5.37 |
115 |
2.72 |
-49 |
|
FEV1 (L) |
4.02 |
3.88 |
96 |
1.45 |
-63 |
|
FEV1/FVC (%) |
86 |
72* |
53 |
||
|
FEF25-75 (L/s) |
4.5 |
2.8 |
63 |
0.6 |
|
|
MVV (L/min) Volumes |
161 |
144 |
89 |
||
|
TLC (L) |
6.06 |
6.68 |
110 |
||
|
RV/TLC(%) |
19 |
20 |
105 |
||
|
Dlco (mL/min |
32 |
30 |
95 |
||
|
per mm Hg) |
Comments
This young man has had asthma and hay fever since age 6 years. He also has exercise-induced asthma and is allergic to certain seafood.
He is presented here to show how extreme the response can be to one breath of methacholine (5 mg/mL). The control curve suggests borderline ventilatory limitation on an obstructive basis, the slope of the flow-volume curve being decreased and the FEV1/FVC ratio slightly reduced. The other test results are normal, and on the basis of these results one would not expect the 63% decrease in the FEV1, which was associated with wheezing and significant dyspnea.
CASE 17
29 y F Wt 110 lb (50 kg) Ht 65 in. (165 cm) BMI 18.4 kg/m2
Comment and Questions
This young woman was a nonsmoker with no history of asthma.
1. How would you grade the limitation based on the flow- volume curve?
2. Do the spirometry results support your impression? (The post-dilator curve is not shown because it could not be distinguished from the control curve.)
3. Are the volumes and Dlco also consistent?
4. What is unusual about this case?
CASE 17
Answers
1. The flow-volume curve shows severe ventilatory limitation due to an obstructive process. The shape of the curve is characteristic of obstruction.
2. Spirometry results are consistent with severe obstruction.
3. The high normal TLC and reduced Dlco are consistent. The low Dlco suggests a parenchymal abnormality such as emphysema.
4. The patient was a nonsmoker with no history of asthma. This degree of obstruction in such a young person is rare. One possibility would be α1-antitrypsin deficiency, but results of blood tests were normal. On open-lung biopsy, the patient was found to have lymphangioleiomyomatosis. This is a rare disease in which there is proliferation of atypical smooth muscle throughout the peribronchial, perivascular, and perilymphatic regions of the lung. Pulmonary infiltrates were prominent on chest radiography (these do not occur in α1-antitrypsin deficiency) and contribute to the reduction in the Dlco. Note that she had a 20% increase in the FVC after a bronchodilator.
CASE 18
73 y F Wt 150 lb (68 kg) Ht 64 in. (162 cm) BMI 25.9 kg/m2
Comments and Questions
This 73-year-old woman complained of cough for 2 months. The cough had begun after a flu-like illness. She was a nonsmoker. She denied wheezing and dyspnea. On examination, her lungs were clear. She had a grade 4/6 harsh precordial systolic murmur.
1. How would you interpret this test? (She did not show any response to inhaled bronchodilator.)
2. What might be the cause of her problem?
CASE 18
Answers
1. On the basis of the area comparison, there is suggestion of a mild ventilatory limitation of a nonspecific nature, the FEV1/FVC ratio being in the normal range. However, the terminal portion of the flow-volume curve suggests the presence of mild obstruction. The markedly reduced diffusing capacity is consistent with a restrictive process due to a lung parenchymal abnormality, but because there is not a measure of TLC, this cannot be confirmed.
2. The loud murmur was the important clue. Her chest radiograph showed an interstitial pattern (easily confused with fibrosis), small bilateral pleural effusions, and an enlarged heart. Results of electrocardiography were also abnormal. With therapy for the congestive heart failure, her cough disappeared, and she lost 12 lb. The flow-volume curve below was then obtained. It was totally normal, and the diffusing capacity also returned to normal.
Congestive heart failure can present with cough as the only significant complaint. The pulmonary function test can mimic a restrictive process due to congested lymphatics and perivascular and peribronchial edema. Comparison of the flow-volume curves indicates that initially mild obstruction was present. Sometimes this can be quite marked and lead to ''cardiac asthma.''
CASE 19
40 y F Wt 213 lb (97 kg) Ht 62 in. (157 cm) BMI 39.4 kg/m2
|
Normal |
Observed |
% predicted |
|
|
Spirometry |
|||
|
FVC (L) |
3.32 |
2.14* |
64 |
|
FEV1 (L) |
2.59 |
1.94* |
75 |
|
FEV1/FVC (%) |
77 |
90 |
|
|
FEF25-75 (L/s) |
3.07 |
2.72 |
89 |
|
MVV (L/min) |
107 |
79 |
74 |
|
Volumes |
|||
|
TLC (L) |
4.65 |
4.02 |
86 |
|
RV/TLC(%) |
32 |
35 |
109 |
Comments and Questions
The patient gave a 4-year history of episodes of shortness of breath. Typically, she awoke in the morning with dyspnea and no wheezing, but some nocturnal cough. Attacks would subside in 1 to 2 days, and she knew of nothing that precipitated them. She was a nonsmoker. Results of physical examination were unremarkable. The lungs were clear, and the heart was normal.
1. What is your interpretation of this test?
2. What do you think the problem is?
3. Are there any other procedures you would order?
CASE 19
Answers
1. The proportionate reduction in the FVC and FEV1 with a normal FEV1/FVC ratio suggests a restrictive process. However, the normal TLC essentially rules out restriction. Thus, ''mild ventilatory limitation on a nonspecific basis'' is the remaining possibility.
2. As shown prEV1ously, a normal FEV1/FVC ratio does not rule out obstruction. Because of the nocturnal nature of the patient's symptoms, you may have suspected asthma.
3. If you ordered a bronchodilator, you were correct. As can be seen from the flow-volume curves below, the post-dilator curve is normal. The FEV1 increased by 25%.
This case reinforces several points:
Not all asthma wheezes.
Asthma is often a nocturnal disorder.
The patient's excess weight for her height (BMI is 39.4 kg/m2) may have tended to make the TLC a bit low.
This is another example of the FEV1/FVC ratio not being an infallible test of obstruction.
The two flow-volume curves really show a parallel shift, as is often seen in mild asthma. In these instances, the FEV1/FVC ratio does not decrease until obstruction increases to a significant degree.
CASE 20
69 y M Wt 143 lb (65 kg) Ht 68 in. (173 cm) BMI 21.7 kg/m2
|
Normal |
Observed |
% predicted |
Post-dilator |
|
|
Spirometry |
||||
|
FVC (L) |
4.11 |
1.73* |
42 |
2.30* |
|
FEV1 (L) FEV1/FVC (%) |
3.18 77 |
0.48* 28* |
15 |
0.63* |
|
FEF25-75 (L/s) |
2.8 |
0.2* |
8 |
0.3* |
|
MVV (L/min) |
124 |
24* |
19 |
|
|
Volumes |
||||
|
TLC (L) |
6.39 |
7.62 |
119 |
|
|
RV/TLC(%) |
36 |
71* |
197 |
|
|
Dlco (mL/min per mm Hg) |
25 |
12* |
47 |
|
Questions
1. How would you interpret this test?
2. What would you predict the pre-dilator MVV would be?
CASE 20
Answers
1. This is a classic case of severe obstructive disease. There is a small but important response to bronchodilator. The reduced Dlco suggests an element of anatomic emphysema. The plateau in the flow-volume curve is typical of severe chronic obstructive pulmonary disease and should not be mistaken for a variable intrathoracic airway lesion.
2. The pre-dilator MVV would be predicted to be 40 x 0.48 (FEV1) = 19 L/min (see section 2I, page 17). The measured value was 24 L/min. This difference does not mean that the FEV1 was in error but merely points out the limitation of the prediction equation and the variability in the relationship between the MVV and FEV1. Of interest, during an exercise study done on the same day, the patient achieved a minute ventilation of 36 L/min. Thus, predicting maximal ventilation during exercise from the FEV1 or MVV may also not be exact.
CASE 21
50 y M Wt 161 lb (73 kg) Ht 68 in. (173 cm) BMI 24.4 kg/m2
|
Spirometry |
Normal |
Observed |
% predicted |
|
FVC (L) |
4.61 |
4.02 |
87 |
|
FEV1 (L) |
3.69 |
3.23 |
88 |
|
FEV1/FVC (%) |
80 |
80 |
|
|
FEF25-75 (L/s) |
3.4 |
3.0 |
88 |
|
MVV (L/min) |
150 |
46* |
31 |
Comments and Questions
This patient complained of dyspnea on climbing stairs. He was a nonsmoker. Results of cardiac examination were negative. Auscultation revealed some decrease in breath sounds. Nineteen years prEV1ously he had had bulbar poliomyelitis, from which he recovered completely. No improvement was seen after he was given a bronchodilator.
1. What is your interpretation?
2. Is there any other procedure you would order?
CASE 21
Answers
1. There is a slight loss of area, but otherwise the flow-volume curve is normal. However, there is a considerable reduction in the MVV. This might reflect a major airway lesion, a neuromuscular problem, or submaximal patient effort.
2. Because the technician thought the patient made a maximal effort on the MVV, you should order an inspiratory flow-volume curve. This was obtained (shown below) and indicated that the patient had a variable extrathoracic major airway lesion. This was due to total paralysis of the right vocal cord and partial paralysis of the left, which resulted in an orifice-like constriction during inspiration.
The tip-off to the diagnosis was the unexplained reduction in the MVV with what seemed to be a good effort. On the basis of the FEV1, you would expect the MVV to be about 129 L/min (3.23 x 40). Thus, this was a striking reduction. However, if the inspiratory flow-volume loop was normal, you would then order maximal respiratory pressure measurements.
CASE 22
68 y M Wt 217 lb (99 kg) Ht 74 in. (188 cm) BMI 28 kg/m2
Question
1. How would you interpret the results?
CASE 22
Answer
1. There is very severe ventilatory limitation on a mixed obstructive and restrictive basis. The restriction is reflected in the reduced TLC. The obstruction is reflected in the decreased expiratory flows and increased curvature of the flow-volume curve. There is a mild reduction of the diffusing capacity.
This is an unusual pattern with severe obstruction and yet a reduced TLC. The patient had undergone a left pneumonectomy 10 years prEV1ously for squamous cell lung cancer. Considering this, the Dlco is well preserved.
CASE 23
45 y F Wt 131 lb (60 kg) Ht 62 in. (157 cm) BMI 24.3 kg/m2
|
Spirometry |
Normal |
Observed |
% predicted |
Post-dilator |
|
FVC (L) |
3.44 |
3.96 |
115 |
4.0 |
|
FEV1 (L) |
2.84 |
2.98 |
105 |
|
|
FEV1/FVC (%) |
82 |
75 |
||
|
FEF25-75 (L/s) |
2.7 |
3.51 |
130 |
|
|
MVV (L/min) |
106 |
122 |
115 |
Comments and Questions
The patient is a 45-year-old woman who for the past 1 to 2 years had noted dyspnea when hurrying on the level or when climbing stairs. She had noted slight arm weakness.
1. What is your interpretation of this test?
2. Is there any other test you would order?
CASE 23
Answers
1. The study results are normal. The shape of the flow-volume curve suggests that the patient was a nonsmoker, which, indeed, she was.
2. Did you order maximal respiratory pressure measurements? Unexplained dyspnea and slight muscle weakness should alert you to the possibility of an early neuromuscular disorder.
|
Normal |
Observed |
% of normal |
|
|
Pimax (cm H2O) |
-70 |
-26* |
37 |
|
PEmax (cm H2O) |
135 |
90* |
67 |
The maximal inspiratory pressure was more reduced than the expiratory pressure. Eventually, amyotrophic lateral sclerosis was diagnosed. This is an example of dyspnea due to muscle weakness appearing at a time when spirometry results were still normal.
CASE 24
|
72 y F Wt 249 lb (113 kg) |
Ht 63 in. (160 cm) |
BMI 44.1 kg/m2 |
|
|
Normal |
Observed |
% predicted |
|
|
Spirometry |
|||
|
FVC (L) |
2.75 |
1.56* |
57 |
|
FEV1 (L) |
2.18 |
1.34* |
62 |
|
FEV1/FVC (%) |
79 |
86 |
|
|
FEF25-75 (L/s) |
2 |
1.7 |
|
|
MVV (L/min) |
86 |
53* |
62 |
|
Volumes |
|||
|
TLC (L) |
4.88 |
3.77* |
77 |
|
RV/TLC(%) |
44 |
51 |
116 |
|
Dlco (mL/min per mm Hg) |
20 |
16 |
79 |
Question
1. What is your interpretation of the results in this 72-year-old nonsmoking woman?
CASE 24
Answer
1. Because there is a loss of area, she has moderate ventilatory limitation. The limitation is restrictive in nature on the basis of the reduced TLC. Although the flow-volume curve is a bit steep, the normal Dlco is against a severe parenchymal process causing the restriction. Thus, the restriction is extrapulmonary and most likely due to the patient's obesity, her BMI being 44.1 kg/m2. This case contrasts with case 15 (page 188), in which even more massive obesity caused no reduction in the FVC and presumably no change in the TLC. On average, obesity with a BMI kg/m2 more than 35 causes a reduction of 5% to 10% in FVC, but the effect of obesity is highly variable. It may be marked, as in this case, or negligible, as in case 15.
CASE 25
42 y F Wt 152 lb (69 kg) Ht 62 in. (157 cm) BMI 28 kg/m2
|
Normal |
Observed |
% predicted |
Post-FVC |
|
|
Spirometry |
||||
|
FVC (L) |
3.32 |
3.34 |
101 |
2.11* |
|
FEV1 (L) FEV1/FVC (%) |
2.81 85 |
2.16* 65* |
77 |
1.46* |
|
FEF25-75 (L/s) |
5.9 |
4.2 |
71 |
|
|
MVV (L/min) |
106 |
41* |
39 |
|
|
Volumes |
||||
|
TLC (L) |
4.69 |
4.26 |
91 |
|
|
RV/TLC(%) |
1.37 |
0.92 |
67 |
|
|
Dlco (mL/min per mm Hg) |
23 |
18 |
77 |
|
Comments
The control flow-volume curve and data are consistent with mild airway obstruction. After the control FVC maneuver, however, audible wheezing developed and the post-FVC curve was obtained. FEV1 was reduced by 32%. This is an example of FVC-induced bronchoconstriction, which occasionally occurs in patients with hyperreactive airways, such as in asthma. The MVV was measured after the FVC maneuver and is reduced because of the induced bronchospasm.
CASE 26
86 y M Wt 137 lb (62 kg) Ht 67 in. (170 cm) BMI 21.5 kg/m2
Comment and Questions
This is a case of an isolated reduction in the Dlco.
1. What might be the cause of this finding?
2. Is there any significance to the contour of the flow-volume curve?
CASE 26
Answers
1. A poor effort or equipment problems could cause this low Dlco value. However, the test was repeated on a different unit and was not changed. The patient was not anemic, but severe anemia could contribute to a reduced Dlco. The tests showed no EV1dence of emphysema. The chest radiograph did show an extensive fine interstitial infiltrate thought to represent metastatic cancer. The mildly reduced RV/TLC ratio might reflect an early restrictive process, but essentially the volumes and spirometry results are normal.
2. The notch in the flow-volume curve was not seen on other efforts and is of no significance.
CASE 27
42 y M Wt 214 lb (97 kg) Ht 74 in. (188 cm) BMI 27.4 kg/m2
|
Normal |
Observed |
% predicted |
Post-dilator |
|
|
Spirometry |
||||
|
FVC (L) |
5.91 |
5.15 |
87 |
5.10 |
|
FEV1 (L) |
4.68 |
3.82* |
82 |
3.87 |
|
FEV1/FVC (%) |
79 |
74 |
||
|
FEF25-75 (L/s) |
4.1 |
2.8 |
67 |
|
|
MVV (L/min) Volumes |
177 |
174 |
99 |
|
|
TLC (L) |
7.60 |
7.75 |
102 |
|
|
RV/TLC(%) |
22 |
30* |
||
|
Dlco (mL/min per mm Hg) |
34 |
56 |
163 |
Comment and Questions
The patient is a moderate smoker.
1. How would you interpret this study?
2. What is particularly unusual, and what might be the cause?
CASE 27
Answers
1. The flow-volume curve suggests mild airway obstruction. The reduced FEV1 is consistent with this impression, even with the normal FEV1 /FVC ratio.
2. The unusual feature is the remarkable increase in the Dlco. Such an increase can occur in asthma, obesity, and polycythemia. The patient had an atrial septal defect with a significant left-to-right shunt. This produced an increased pulmonary capillary blood volume and, hence, the high Dlco.
CASE 28
31 y F Wt 105 lb (48 kg) Ht 65 in. (165 cm) BMI 17.6 kg/m2
Questions
1. How would you interpret this test?
2. Do the flow-volume curve and test data suggest the need for other tests?
CASE 28
Answers
1. There is significant ventilatory limitation (that is, loss of area under the flow-volume curve). The curve is steep, but the normal TLC and diffusing capacity rule out a pulmonary parenchymal restrictive process. At this point, this case can be classified as a nonspecific abnormality.
2. There are no findings to suggest a major airway lesion. However, another possible cause of such a pattern is a neuromuscular problem. Maximal respiratory pressures should be determined to assess respiratory muscle strength.
The values follow:
|
Normal |
Patient |
% normal |
|
|
Pimax (cm H2O) |
-88 |
-64* |
30 |
|
PEmax (cm H2O) |
154 |
113* |
23 |
The patient has severe amyotrophic lateral sclerosis. The muscle weakness led to the decreased FVC and FEV1 and the increased RV/TLC ratio. Surprisingly, a normal TLC was maintained. Compare this case to case 23 (page 208), a less severe case of muscle weakness.
CASE 29
64 y F Wt 142 lb (64 kg) Ht 60 in. (152 cm) BMI 27.7 kg/m2
|
Spirometry |
Normal |
Observed |
% predicted |
Post-dilator |
|
FVC (L) |
2.60 |
2.76 |
106 |
2.70 |
|
FEV1 (L) |
2.13 |
1.84 |
86 |
1.85 |
|
FEV1/FVC (%) |
82 |
67 |
82 |
69 |
|
FEF25-75 (L/s) |
2.2 |
2 |
91 |
|
|
MVV (L/min) |
87 |
27* |
31 |
Comment and Question
This nonsmoker complained of the gradual onset over 5 years of dyspnea on exertion, often associated with noisy breathing.
1. What is your preliminary diagnosis, and how would you proceed?
CASE 29
Answer
1. The history, shape of the flow-volume curve, and isolated reduction in MVV should suggest ''major airway lesion.'' Then, a flow-volume loop would be ordered, which is shown in the figure below.
The patient had an idiopathic subglottic stenosis leading to the pattern of a fixed major airway lesion. The stricture was removed, and the postoperative flow-volume loop was normal.
CASE 30
31 y M Wt 226 lb (103 kg) Ht 72 in. (182 cm) BMI 31.1 kg/m2
|
Normal |
Observed |
% predicted |
|
|
Spirometry |
|||
|
FVC (L) |
5.23 |
4.43 |
85 |
|
FEV1 (L) |
4.12 |
3.48 |
84 |
|
FEV1/FVC (%) |
79 |
78 |
|
|
FEF25 - 75 (L/s) |
3.6 |
2.6 |
73 |
|
MVV (L/min) |
158 |
137 |
87 |
|
Volumes |
|||
|
TLC (L) |
7.11 |
7.38 |
104 |
|
RV/TLC(%) |
27 |
36* |
|
|
Dlco (mL/min per mm Hg) |
33 |
26 |
79 |
|
O2 saturation (%) |
|||
|
Rest |
96 |
90* |
|
|
Exercise |
96 |
85* |
|
Questions
1. Is there anything in the data to explain the subject's desaturation?
2. Can you rule out some possible causes?
CASE 30
Answers
1. Nothing in the data indicates the cause of the subject's desaturation. The mild increase in the RV/TLC ratio is not helpful.
2. The flow-volume curve shows borderline ventilatory limitation, but nothing indicates the cause of the problem. The TLC and Dlco effectively rule out lung parenchymal disease. The patient is mildly overweight (BMI is 31.1 kg/m2), but the weight is not severe enough to cause this problem.
The patient had advanced liver disease with small intrathoracic right-to-left shunts causing the desaturation. The patient exhibited orthodeoxia; namely, the saturation decreased when he went from the recumbent to the standing position. He underwent liver transplantation, which was successful, and the desaturation was abolished.
CASE 31
46 y M Wt 246 lb (112 kg) Ht 65 in. (165 cm) BMI 41.1 kg/m2
Question
1. How would you interpret the test results?
CASE 31
Answer
1. The first thing to be noted is that the post-dilator flow- volume curve is lower than the control curve. This is a paradoxical response to isoproterenol (Isuprel), and a fairly rare occurrence. When the patient was tested later with albuterol, there was not such a decrease in flows and some improvement was seen in the curve. In addition, the control curve shows mild, nonspecific ventilatory limitation. The ''scooping'' of the flow-volume curve and the increased RV/TLC ratio suggest an obstructive process. The patient is obese (BMI is 41.1 kg/m2). This may contribute to the reduction in FVC and FEV1.
CASE 32
14 y F Wt 110 lb (50 kg) Ht 64 in. (162 cm) BMI 19.1 kg/m2
|
Normal |
Observed |
% predicted |
|
|
Spirometry |
|||
|
FVC (L) |
3.28 |
3.28 |
100 |
|
FEV1 (L) |
2.9 |
2.93 |
101 |
|
FEV1/FVC (%) |
88 |
89 |
|
|
FEF25-75 (L/s) |
3.5 |
3.1 |
88 |
|
MVV (L/min) |
116 |
117 |
101 |
|
Volumes |
|||
|
TLC (L) |
4.5 |
4.3 |
96 |
|
RV/TLC(%) |
19 |
21 |
|
|
Dlco (mL/min per mm Hg) |
23 |
23 |
100 |
Comments
The baseline data are all normal. Because of the patient's history of intermittent wheezing and shortness of breath, a methacholine challenge test was performed. The patient inhaled five breaths of methacholine and her flows promptly decreased (curve 1), and the FEV1 decreased 62%. As repeated FVCs were obtained, the bronchospasm progressively decreased, and eventually the FEV1 was reduced by only 14%, which is usually considered a negative test result. However, in this situation, it seems clear that the patient has hyperreactive airways. In this case, the mere effort of inhaling to TLC decreased the degree of bronchoconstriction, which can occur during a methacholine challenge, although this is an extreme example. The more usual behavior in the way we do the challenge is shown in Figure 5-5.
Also note the terminal portion of the control flow-volume curve. At approximately 3.2 L exhaled volume, the flow decreases precipitously to zero. As shown in Fig. 2-6E (page 16), such a curve can be a normal variant, as in this case. With bronchoconstriction, this feature is lost, but it is seen again as the bronchoconstriction subsides (see determinants of RV, page 30 and the second Pearl, page 40).
CASE 33
36 y F Wt 211 lb (95.5 kg) Ht 63 in. (160 cm) BMI 37.3 kg/m2
|
Normal |
Observed |
% predicted |
|
|
Spirometry |
|||
|
FVC (L) |
3.57 |
1.90* |
53 |
|
FEV1 (L) |
3.02 |
0.72* |
24 |
|
FEV1/FVC (%) |
85 |
38* |
|
|
FEF25-75 (L/s) |
3.1 |
0.8* |
26 |
|
MVV (L/min) |
100 |
58* |
58 |
|
Volumes |
|||
|
TLC (L) |
5.20 |
4.91 |
94 |
|
RV/TLC(%) |
30 |
61* |
|
|
Dlco (mL/min per mm Hg) |
24 |
11* |
46 |
Comments and Questions
This 36-year-old woman had noted progressive shortness of breath during the past 6 years. She was a nonsmoker and had no history of asthma or a family history of lung disease. The chest radiograph revealed diffuse interstitial infiltrates. There was no response to bronchodilator.
1. What is your impression based on the above data?
2. Are there aspects of the data that are unusual?
3. Are there additional tests that might be informative?
CASE 33
Answers
1. This is a puzzling case. Obstruction is reflected in the flow- volume curve contour and the very low FEV1, FEF25-75, and FEV1/FVC and the increased RV/TLC. The TLC is not increased, which is unusual with this degree of obstruction. The low Dlco and the chest radiograph suggest a possible restrictive component.
2. Lung mechanics testing was performed. Resistance was increased threefold, whereas CLstat was reduced to 56% of predicted and CLdyn to 30% predicted. The graphic data emphasize the lack of hyperinflation, the low maximal expiratory flows, and the relatively normal lung recoil curve. The resulting MFSR curve is consistent with extensive airway disease.
3. A lung biopsy helped with the diagnosis of lymphangio- leiomyomatosis. In this case, despite the severe obstruction, there was no increase in either the TLC or CLstat, a very unusual situation, which often occurs in this disease (see page 115, and case 17, page 192).
CASE 34
62 y F Wt 90 lb (40 kg) Ht 63 in. (160 cm) BMI 15.6 kg/m2
|
Normal |
Observed |
% predicted |
Post-dilator |
|
|
Spirometry |
||||
|
FVC (L) |
2.6 |
1.95* |
75 |
1.95 |
|
FEV1 (L) |
1.9 |
0.35* |
18 |
0.35 |
|
FEV1/FVC (%) |
74 |
18* |
||
|
FEF25-75 (L/s) |
2.9 |
0.3* |
10 |
|
|
MVV (L/min) Volumes |
62 |
16* |
25 |
|
|
TLC (L) |
4.6 |
5.5 |
120 |
|
|
RV/TLC(%) |
43 |
66* |
153 |
|
|
Dlco (mL/min per mm Hg) |
22 |
8* |
36 |
Comments and Questions
This 62-year-old woman complained of weight loss, rectal bleeding, nervousness, and some shortness of breath on exertion. She noted dyspnea after having the Hong Kong flu. She had never smoked and had no family history of respiratory disease. The chest radiograph revealed cystic changes at both bases. The TLC measured with the nitrogen washout technique was 1 liter less than that with the plethysmographic TLC reported here.
1. How would you describe these data?
2. Are there any additional tests you would order?
CASE 34
Answers
1. The test results are consistent with severe airway obstruction with hyperinflation, yet dyspnea was not a major complaint. The chest radiograph and the low diffusing capacity suggest the presence of emphysema.
2. A test for α1-antitrypsin deficiency revealed she was homozygous for the Z gene. Special mechanics studies were ordered. Note the severe loss of lung recoil and hyperinflation. The MFSR curve lies in the normal range, consistent with the condition being pure emphysema. CLstat was increased (0.389 L/cm H2O), whereas CLdyn was low (0.132 L/cm H2O) (see section 7B, page 79). Resistance was increased at 6.2 cm H2O/L per second.
CASE 35
56 y M Wt 162 lb (73.6 kg) Ht 66 in. (168 cm) BMI 26.1 kg/m2
|
Normal |
Observed |
% predicted |
Post-dilator |
|
|
Spirometry |
||||
|
FVC (L) |
3.3 |
4.67 |
141 |
4.67 |
|
FEV1 (L) |
2.4 |
1.72* |
72 |
2.02 |
|
FEV1/FVC (%) |
73 |
37* |
||
|
FEF25-75 (L/s) |
3.4 |
0.7* |
21 |
|
|
MVV (L/min) Volumes |
103 |
79* |
79 |
|
|
TLC (L) |
5.7 |
8.1* |
142 |
|
|
RV/TLC(%) |
42 |
42 |
101 |
|
|
Dlco (mL/min per mm Hg) |
27 |
26 |
96 |
Comments and Questions
This 56-year-old man had a 4-year history of progressive dyspnea on exertion. He reported a productive morning cough and occasional wheezing. He had a 30 pack-year history of cigarette smoking. Coarse inspiratory and expiratory wheezes and rhonchi were heard. The chest radiograph was normal. Arterial blood gas tests at rest showed an O2 saturation of 93%, Pao2 64 mm Hg, Paco2 33 mm Hg, and pH 7.52.
1. How would you classify these data?
2. Are there any concerns you have about these data?
3. Are there other data you would like to have?
CASE 35
Answers
1. There is a mild degree of airway obstruction with a good FEV1 response (17%) to bronchodilator. The normal Dlco is not compatible with an extensive degree of emphysema.
2. Note that the patient was hyperventilating (low Paco2 and increased pH) when the arterial sample was drawn.
3. To rule out emphysema, a mechanics study was done (see below). Note that despite the hyperinflation, the lung recoil is normal and the MFSR curve is to the right of the normal range, indicating that airway disease (chronic bronchitis) was the cause of the low expiratory flows. Rpulm was high (5.0 cm H2O/L per second), CLstat was normal (0.250 L/cm H2O), and CLdyn was low (0.133 L/cm H2O).
CASE 36
18 y F Wt 126 lb (57 kg) Ht 64 in. (162 cm) BMI 21.7 kg/m2
Questions
1. What is your interpretation?
2. The patient had a history of colds with some wheezing. Is there anything else that should be done?
CASE 36
Answers
1. The test is normal. Note the high-normal Dlco. This may be a subtle sign of underlying asthma.
2. Because of the history, you probably ordered a methacholine challenge test. The test was strongly positive after one breath of 25 mg/mL methacholine.
This case illustrates the importance of considering the reactivity of the airways at the time of testing. When the first test was done, the airways were fully dilated and there was no response to bronchodilator. Hence, methacholine was needed to confirm the diagnosis. In some situations, the airways may be constricted such that methacholine will have no effect but a dilator will. In this case, the control FEV1/FVC ratio was 80%, during the 67% reduction in FEV1 the ratio was 76%, and it was 81% on the postdilator curve. This again shows that the ratio does not always detect airway obstruction.
CASE 37
45 y F Wt 265 lb (119 kg) Ht 65.8 in. (167 cm) BMI 42.7 kg/m2
|
Normal |
Observed |
% predicted |
Post-challenge |
|
|
Spirometry |
||||
|
FVC (L) |
3.68 |
3. 66 |
100 |
|
|
FEV1 (L) |
3.01 |
2.83 |
94 |
-14 |
|
FEV1/FVC (%) |
82 |
77 |
||
|
FEF25-75 (L/s) |
2.8 |
2.4 |
87 |
|
|
MVV (L/min) |
110 |
100 |
92 |
|
|
Dlco (mL/min per mm Hg) |
24 |
31 |
129 |
Comments and Questions
This 45-year-old nurse was being treated for hypertension and complained of cough and wheezing with exertion. Physical examination was normal except for a blood pressure of 160/96 mm Hg. Her medications were not the cause of her cough. Note the negative methacholine challenge study.
1. What may be important in the data above?
2. Would you order any additional studies?
CASE 37
Answers
1. The patient is obese with a weight/height ratio of 0.72 and BMI of 42.7 kg/m2. Obesity likely explains the increased Dlco because the challenge was negative for asthma.
2. An exercise study was ordered and flow-volume loops were obtained. Both at rest and during exercise, as shown below, the patient breathed very near residual volume and on the expiratory limb of her maximal flow-volume curve.
Breathing on the flow-volume curve often occurs in obese subjects and produces expiratory wheezing due to compression of the airways. Try breathing near residual volume and you likely will also wheeze. We term this pseudoasthma, and it almost always is associated with obesity and, often, many trips to the emergency department.
CASE 38
43 y F Wt 131 lb (59 kg) Ht 68 in. (173 cm) BMI 19.7 kg/m2
|
Spirometry |
Normal |
Observed |
% predicted |
Post-challenge |
|
FVC (L) |
3.93 |
3.81 |
97 |
2.97 |
|
FEV1 (L) |
3.18 |
2.80 |
88 |
2.18* |
|
FEV1/FVC (%) |
81 |
73 |
||
|
FEF25-75 (L/s) |
2.8 |
2.1 |
75 |
|
|
MVV (L/min) |
114 |
99 |
87 |
Comments
The observed values are all within normal limits. However, the slope of the flow-volume curve is reduced to 1.44 L/s per liter, whereas it should be 2.0 or more (see section 2F, page 12). Because of this finding and a history of episodes of bronchitis with mild dyspnea, a methacholine challenge was performed. There was a 22% decrease in the FEV1 after only three breaths of methacholine (see section 5F, page 57). A reduced slope of the flow-volume curve may mean airway disease, in this case asthma (see case 16, page 190). However, occasionally a reduced slope is found in normal subjects who are thin and taller than 6 feet.
CASE 39
77 y M Wt 150 lb (68 kg) Ht 72 in. (182 cm) BMI 20.5 kg/m2
|
Normal |
Observed |
% predicted |
|
|
Spirometry |
|||
|
FVC (L) |
4.72 |
1.83* |
39 |
|
FEV1 (L) |
3.53 |
1.83* |
52 |
|
FEV1/FVC (%) |
75 |
99.7 |
|
|
FEF25-75 (L/s) |
2.8 |
6.1 |
216 |
|
MVV (L/min) |
126 |
93* |
74 |
|
Volumes |
|||
|
TLC (L) |
7.16 |
4.75* |
66 |
|
RV/TLC (%) |
34 |
61* |
179 |
|
Dlco (mL/min per mm Hg) |
25 |
Comments
There was no response to bronchodilator. Oxygen saturation was normal at rest and exercise. The shape of the flow-volume curve, reduced TLC and Dlco, and high FEV1/FVC ratio are all consistent with a moderate parenchymal restrictive process such as fibrosis. However, the normal oximetry result is not compatible with this. The patient had congestive heart failure with bilateral pleural effusions. Basilar fibrosis was noted. Congestive heart failure can mimic pulmonary fibrosis. Contrast this case with case 18, page 195, which had a suggestion of obstruction. Thus, congestive heart failure may present with either a restrictive or an obstructive pattern.
CASE 40
Annual monitoring of change in lung function can identify persons with accelerated decline due to smoking, occupational exposures, or other causes. This person has normal lung function, which is stable over 9 years of employment. The estimated rate of decline in FEV1 is -17 mL/y, which is normal.
Case 40
(This is an actual trend report with data from individual tests plus grades for maneuver quality.)
CASE 41
This person, a smoker in a respiratory protection program, has had a rapid decline in lung function over 8 years. Mild obstruction has developed, and he is likely to be disabled before retirement unless appropriate preventive measures are taken. The estimated rate of decline in FEV1 is -138 mL/y.
Case 41
CASE 42
More frequent monitoring may be needed for persons with labile lung function, such as those with asthma, and for persons with lung injury or lung transplantation. This trend shows gradual improvement in lung function of an employee of a chemical plant who was exposed to chlorine in an industrial accident. Lung function improved rapidly during the first month after his injury, then slowly during the following 5 years.
Case 42
CASE 43
This trend from a patient who had lung transplantation shows gradual improvement over 2 months, then an episode of rejection, which was treated successfully 7 months after transplantation. Values indicated by an ''X'' were deleted from analysis because they were outliers caused by a wet flow element (see Case 45).
Case 43
CASE 44
This trend shows the progressive decline in function of a patient with obliterative bronchiolitis after lung transplantation.
Case 44
CASE 45
This trend is highly variable with frequent ''spikes'' showing artifactual increases in FEV1. These were due to the patient's use of a wet spirometer flow sensor. The moisture increases the flow resistance of the element, giving an increase in driving pressure and causing an overestimate of his FEV1. Values indicated by an ''X'' were deleted from analysis because they were outliers caused by a wet flow element. After the patient was reinstructed in proper care of the spirometer, the artifact was eliminated.
Case 45
