| Pulmonary function tests are a series of tests that evaluate how well the lungs are working.
There are many components included in pulmonary function tests, most of which can be divided into two types of testing, spirometry and lung volume measurements. Spirometry includes the forced vital capacity (FVC), forced expiratory volume in 1 second (FEV-1) and peak expiratory flow rate (PEFR). Lung volume measurements include maximum voluntary ventilation (MVV), total lung capacity (TLC), vital capacity (VC), and residual volume (RV). Diffusion capacity (DLCO) and arterial blood gases are other tests that are occasionally performed.
FVC measures the total amount of air that can be forcefully expelled from the lungs after taking a deep breath. FEV-1 measures the amount of air that can be forcefully expelled in the first second of this exhalation effort. These measures, as well as the peak expiratory flow rate (PEFR) quantify the extent of airways obstruction, as might occur with asthma or chronic obstructive lung disease.
Vital capacity (VC), total lung capacity (TLC), and residual volume (RV) are all measures of lung volumes. The maximum amount of air that an individual's lungs can hold is measured by TLC, and the amount of air left in the lungs after forced expiration is measured by RV. These are helpful in the assessment of restrictive lung diseases, such as pulmonary fibrosis. MVV measures the maximum volume of air that an individual can breathe in and out in 1 minute, and can be helpful in evaluating respiratory muscle function.
The arterial blood gas (ABG) test indicates how efficiently the lungs move oxygen into and remove carbon dioxide from the blood by measuring the level of those gases in the blood. A variation of this test, pulse oximetry, is a noninvasive test that measures the percentage of oxygenation of the blood.
Pulmonary function tests are the most definitive tests for assessing pulmonary function and for managing individuals with lung disease such as chronic obstructive pulmonary disease (COPD) or pulmonary fibrosis. |
Source: Medical Disability Advisor
| Pulmonary function tests measure the extent and level of respiratory impairment in an individual, help diagnose lung diseases such as pulmonary fibrosis, asthma, bronchitis, COPD, and emphysema, and evaluate response to therapy for lung conditions. These tests are also required for workplace respiratory surveillance programs to ensure the safety of workers using positive pressure respirator devices, and are usually conducted at a minimum of yearly intervals.
Individuals who have recently had a heart attack, and individuals with some other cardiac conditions should not perform these tests (except for arterial blood gas). Individuals whose breathing is limited by pain (e.g., broken ribs) may not produce accurate results. |
Source: Medical Disability Advisor
| The most common pulmonary function tests that are performed involve a procedure called spirometry. The individual breathes through a tube that is connected to a machine called a spirometer. The machine records the volume of air moved and the time during a forced exhalation. A similar machine that may be more readily available, a peak flow meter, is used to measure PEFR during a forced exhalation. If airflow appears to be obstructed, the test may be repeated after administration of an inhaled bronchodilator (bronchoprovocation testing).
Total lung volume can be measured by body plethysmography. The individual sits in a transparent sealed box similar to a telephone booth and breathes in and out through a mouthpiece. A sensor measures changes in air pressure in the box, and from these measurements, an accurate measure of lung volume can be determined.
Diffusion capacity is measured by having a person take a breath of air with a known small concentration of carbon monoxide and then exhale. The concentration of carbon monoxide is measured in the exhaled air. From this measurement, the rate at which gas travels from the lungs into the blood can be calculated.
All of these tests require that the individual be able to understand and comply with the test directions and that the individual is able to inhale and exhale deeply without being limited by pain.
The arterial blood gas measurement is performed on blood that has been drawn from an artery using a syringe. The pulse oximetry test uses sensors placed on a fingertip or earlobe. The sensors are connected to a machine, called an oximeter, that provides an estimate as to how much oxygen is in the blood. Taken together, these tests give a very good picture of lung health or dysfunction. |
Source: Medical Disability Advisor
| When variation among testing protocols and compliance of individuals being tested is minimized through the use of standardized methodology, pulmonary function tests yield valid and dependable results with no adverse effects to the individual. |
Source: Medical Disability Advisor
| Individuals may become light-headed or rarely may faint during the test. In individuals with asthma, the tests may trigger bronchoconstriction that requires treatment. Individuals with severe lung disease may become exhausted by the testing. |
Source: Medical Disability Advisor
| Restrictions and accommodations are not associated with this procedure. |
Source: Medical Disability Advisor
| "Lung Function Tests." WebMD.com. WebMD Inc. 24 May 2005 <http://my.webmd.com/hw/health_guide_atoz/hw5022.asp?lastselectedguid+{5FE84E90-BC77-4056-A91C-9}>. |
Source: Medical Disability Advisor