Welcome To The Pulmonary Function Room
Pulmonary Function Tests - A Systematic Way To Interpretation
There is a systematic way to read the PFT and be able to evaluate it for the presence of
obstructive or restrictive disease. The following steps will be helpful.
- Step 1. Look at the forced vital capacity (FVC) to see if it is within normal limits.
- Step 2. Look at the forced expiratory volume in one second (FEV1) and determine if
it is within normal limits.
- Step 3. If both FVC and FEV1 are normal, then you do not have to go any further -
the patient has a normal PFT test.
- Step 4. If FVC and/or FEV1 are low, then the presence of disease is highly
likely.
- Step 5. If Step 4 indicates that there is disease then you need to go to the %predicted
for FEV1/FVC. If the %predicted for FEV1/FVC is 88%-90% or higher, then the patient
has a restricted lung disease. If the %predicted for FEV1/FVC is 69% or lower, then the
patient has an obstructed lung disease.
How Do You Tell If The Patient Is Normal or Has Mild, Moderate or Severe Pulmonary Disease ?
There are a number of systems which physicians use to determine the severity of disease.
Here is just one way that is very commonly used :
- Normal PFT Outcomes - > 85 % of predicted values
- Mild Disease - > 65 % but < 85 % of predicted values
- Moderate Disease - > 50 % but < 65 % of predicted values
- Severe Disease - < 50 % of predicted values
In most good spirometers on the market today, there is a set of normal tables (sometimes
multiple sets of tables) which can be chosen as you perform the PFT. Also, there are
interpretive microchips in the PFT machines which will tell you what the diagnosis is for
a particular patient. These two features make it easy for the clinician to immediately see
what the predicted values (normal table values) are for a specific patient and whether or
not the PFT has a normal observed outcome. The PFT data are examined by the
computerized spirometer and a diagnosis of obstructive or restrictive disease is made.
Instructions: Use the evaluation methods presented in class and reproduced here on this web page to help you learn how to evaluate a pulmonary function test report. Please try to determine if the patients represented in these ten (10) pulmonary function tests are normal, or if they have obstructive or restrictive disease. Also attempt to determine
if they have mild, moderate or severe disease.
Pulmonary Function Test Problems
Case # 1.
| Predicted Values | Measured Values |
% Predicted |
FVC | 6.00 liters | 4.00 liters | 67 % |
FEV1 | 5.00 liters | 2.00 liters | 40 % |
FEV1/FVC | 83 % | 50 % | 60 % |
Decision : This person is : ______________________________
Case # 2.
| Predicted Values | Measured Values | % Predicted |
FVC | 5.68 liters | 4.43 liters | 78 % |
FEV1 | 4.90 liters | 3.52 liters | 72 % |
FEV1/FVC | 84 % | 79 % | 94 % |
Decision : This person is ______________________________
Case # 3.
| Predicted Values | Measured Values | % Predicted |
FVC | 5.04 liters | 5.98 liters | 119 % |
FEV1 | 4.11 liters | 4.58 liters | 111 % |
FEV1/FVC | 82 % | 77 % | 94 % |
Decision : This person is ______________________________
Case # 4.
| Predicted Values | Measured Values | % Predicted |
FVC | 3.20 liters | 2.78 liters | 87 % |
FEV1 | 2.51 liters | 2.19 liters | 87 % |
FEV1/FVC | 78 % | 79 % | 101 % |
Decision : This person is ______________________________
Case # 5.
| Predicted Values | Measured Values | % Predicted |
FVC | 3.20 liters | 3.01 liters | 94 % |
FEV1 | 2.51 liters | 1.19 liters | 47 % |
FEV1/FVC | 78 % | 39 % | 50 % |
Decision : This person is ______________________________
Case 6.
| Predicted Values | Measured Values | % Predicted |
FVC | 4.80 liters | 4.10 liters | 85 % |
FEV1 | 3.65 liters | 3.10 liters | 85 % |
FEV1/FVC | 76 % | 76 % | 100 % |
Decision : This person is ______________________________
Case # 7.
| Predicted Values | Measured Values | % Predicted |
FVC | 5.80 liters | 4.98 liters | 86 % |
FEV1 | 4.70liters | 4.38 liters | 93 % |
FEV1/FVC | 81 % | 88 % | 109 % |
Decision : This person is ______________________________
Case # 8.
| Predicted Values | Measured Values | % Predicted |
FVC | 2.30 liters | 1.88 liters | 82 % |
FEV1 | 1.65 liters | .7 liters | 42 % |
FEV1/FVC | 72 % | 37 % | 51 % |
Decision : This person is ______________________________
Case # 9.
| Predicted Values | Measured Values | % Predicted |
FVC | 7.20 liters | 6.01 liters | 83 % |
FEV1 | 6.45 liters | 5.35 liters | 83 % |
FEV1/FVC | 90 % | 89 % | 99 % |
Decision : This person is ______________________________
Case 10.
| Predicted Values | Measured Values | % Predicted |
FVC | 6.76 liters | 4.78 liters | 71 % |
FEV1 | 5.00 liters | 2.00 liters | 40 % |
FEV1/FVC | 74 % | 42 % | 56 % |
Decision : This person is ______________________________