Pulmonary
- Critical Care Associates
of East Texas
Jeffrey M.
Shea, M.D., F.C.C.P.
Venkatesh Donty, M.D.
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Jeffrey M.
Shea, M.D., F.C.C.P. |
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Introduction Pulmonary function testing is a method of determining how well your lungs and airways are working. These tests may be done on a routine basis. It gives the physician a series of numbers, which allows them to compare each patient’s lung function with a predicted value based on age, height, and sex, as well as their lung function in the past. Following these tests closely allows the physician to intervene early when lung function is failing and to fine tune your therapy. Reasons For Pulmonary Function Tests Evaluation of pulmonary function can be of benefit for a variety of reasons. They are as follows:
What Do Pulmonary Function Tests Measure? The term Pulmonary Function Test is a general term; there are many pulmonary function tests. Each test gives different information. The most common pulmonary function test is called a spirometry. During this test you take in as deep a breath as possible, and blow out all of the air as fast and as hard as you can. You will make several attempts at this procedure to assure that your best performance has been measured. You will do a spirometry before and after breathing in a bronchodilator, changes that may occur after breathing this in allows your doctor to make changes in your therapy properly. The most common abnormality seen in patients is obstructive disease. With infection, inflammation, mucus and muscle constriction in the airways, when asked to forcefully exhale, the airflow is lower than normal. This is called a flow volume curve. On a normal flow volume curve the flow rapidly rises to a peak, and then the descending limb of the flow volume curve is straight. With obstructive disease, the descending limb of the flow volume curve is scooped out or concaved. The concave appearance represents decreased airflow. The second common pulmonary function test is called lung volumes. This test is usually done in a body plethysmograph or body box. This booth has clear plexi-glass all around. You sit in this booth with the door closed and pant into a mouthpiece. These measurements can calculate the total amount of air in your lungs when you have blown out all the way. The total amount of air in your lungs after a full inspiration is called total lung capacity. The amount of air in your lungs after you have fully exhaled is called residual volume. The ratio of these two numbers is a sensitive measure of lung disease. Terms used in pulmonary function are: FVC- forced vital capacity, the total amount of air that can be blown out after inhaling as deeply as possible and then blowing out as hard and forcefully and long as possible. FEV1- forced expiratory volume in one second, the amount of air that is blown out in the first second of the forced vital capacity maneuver. FEF max- forced expiratory flow, maximum: the fastest flow that can be forcefully blown out. FEF25-75- forced expiratory flow between 25% and 75% of the vital capacity, the fastest flow that can be forcefully blown out within the middle half of the forced vital capacity maneuver. Types of Pulmonary Disease Obstructive Disease
Restrictive Disease
Patients can have a combined obstructive and restrictive disorder. Example of this may be emphysema (obstructive) with mild congestive heart failure (restrictive). Summary Pulmonary function tests are just one of other test used to diagnose pulmonary disease and to rule out any other lung abnormalities. With routine PFT’s the doctor is able to treat the patient accordingly with the proper medication and instruct with preventive health measures. |
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