Spirometry Test

There are several important tests used by healthcare providers to determine whether an obstructive or restrictive lung disease is present. The term used to group these procedures is Pulmonary Function Tests, also called PFTs, and they do more than just determine the type of lung disease that may be present but can also provide answers as to where the problem is located as well. The term PFTs refers to a variation of different pulmonary testing that can be performed by healthcare professionals that help to give insight as to how well an individual's lungs are working. Some of these tests, such as spirometry and lung volumes provide this information by measuring airflow and lung capacity. Others such as diffusion capacity and the arterial blood

gases test help by measuring the movement of oxygen to and from the blood and how well the lungs can flush CO2 out. Most PFTs are effort dependent, therefore it is necessary to ensure the individual being tested is giving their maximum effort. PFTs are interpreted by comparing their results to charts of predicted values, which are often programmed into the devices used to perform the tests. These predicted values are formulated from research studies of asymptomatic nonsmokers of varying ages and heights, gender, and sometimes varying ethnic/racial backgrounds (Townsend 576).
Of these pulmonary function tests, spirometry is the fastest, cheapest and most accessible. By measuring an individual's airflow, spirometry is used to determine whether or not an obstructive pulmonary disease is present as well provide some insight as to whether a restrictive disease may be present. To properly orchestrate this procedure, an individual will be asked to take in as deep of a breath as possible, then exhale into the spirometry device as fast and as long as they can. The spirometry device then measures not only the amount of air exhaled but the amount of time it took for the air to be exhaled.

During this test, clamps are placed on the nose of the participant to isolate the airflow being measured exclusively to and from the mouth. This test is then done usually two to three times to ensure the accuracy and the use of bronchodilators may be called upon with before and after tests to see if the use of medicine may be a viable solution. Upon reading the results of the spirometry test there are three key measurements, the FEV1, FVC and the FEV1/FVC ratio. The first measurement, forced expiratory volume 1 or FVC1, is the volume of air forcefully exhaled after one second of exhalation. This makes up the first portion of the forced vital capacity or FVC, which is the volume in liters of air

measured forcefully from the peak of inspiration to full exhalation, until the patient can breath out no more.

Lastly, there is the FEV1/FVC ratio. This ratio represents the percent of the lung size (FVC) that can be measured in one second and is calculated by dividing the measured FEV1 by the measured FVC, then converted it to a percentage. If the FEV1/FVC ratio is less than 80%, this indicates that an obstructive pulmonary defect is present. Once it is verified that there is indeed a defect, this ratio can also be used to determine the severity of it. To get this reading, the FEV1 percentage is used. If this percentage is slightly above 80%, this could indicate minimal obstructive defect. If the percentage falls between 65-80%, it would be considered a mild defect, between 50-65% moderate and anything less than 50% would be considered severe (Baptist 1). Since these numbers are approximations, they also need to be interpreted in the appropriate predicted values chart, taking into account the height, age and weight of the patient receiving the test, in healthy adult males this ratio should fall somewhere between 70-80%. Upon taking a

spirometry test and getting his FEV1/FVC ratio results, Kyle’s readings came out to be 1.7 L./4 L. - 42% in 2001, and then 0.9 L./ 3.6 L. - 25% in 2007, when he got the test done again. In 2001, his FEV1/FVC ratio was already far below normal indicating a severe obstructive pulmonary disease, which then fell even lower with his test in 2007. Once the question of presence and severity is answered, the next thing that can be determined by spirometry is whether a restrictive defect may be present. Although spirometry cannot give a definitive answer as to whether a restrictive defect is present, the FVC value can be used as an indicator. If the FVC value is less than 80% of normal value and does not reverse with the use of bronchodilators, this would indicate that a restrictive lung disease could be present (Baptist 1). By comparing Kyle’s FVC value to a chart of predicted values for his age and gender, possible signs of restrictive lung disease can be seen. The normal FVC value for a healthy adult male is around 4.8 L., while Kyle’s FVC value fell from 4 liters to 3.6 liters, over a period of six years. Comparing Kyle’s values to his predicted values shows he may in fact have a restrictive lung defect along with an apparent obstructive defect as both of these types of diseases can be present in an individual at the same time. However, a restrictive defect is defined by a decreased total lung capacity (TLC) which cannot be measured by a spirometer, so further testing would be needed to really verify if this were the case. That is where lung volume testing comes into play.
Lung volume testing, another one of the PFTs, measures the total volume of an individual's lungs and how well the oxygen breathed in is distributed throughout. This test is usually done when there is a suspected restrictive disease present, after seeing the results of spirometry or a chest X-ray. It is also the next option for healthcare providers to take after testing the use of bronchodialaters before and after spirometry, if the values do not climb back up to that of normal range or within an acceptable percent. Although there are many different measurements that can be taken with lung volume testing, such as vital capacity, residual volume and tidal volume, the variable focused on in Kyle's pulmonary function testing was his TLC or