Pulmonary Function Room

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 %