What is spirometry | Diseases and conditions: Medical tests.


Spirometry is a test that allows to know the State of the lungs of a person by measuring the air that is able to inspire and exhaling.
There are two types of basic spirometry:
Simple spirometry: consists in that the person slowly first breathe normally. Then you need to catch and release all the air that can. The volume of air that enters and leaves the lungs, and the maximum that could enter and exit is thus measured.
Forced spirometry: consists in that the person will pick all of the air that you can and then release suddenly until it can not expel more. It is most useful for the study of broncopatias. Flow, i.e., the amount of air per second which can expel a person is thus measured.
Spirometry will not say directly what is the lung problem that we face, but yes it tells us if the lung function is altered with an obstructive pattern (the air cannot leave easily) or restrictive (the air cannot enter). This helps a lot to decide a useful treatment, and allows you to focus on clinical diagnosis or other tests.
Other types of trials are those that are performed after a test of bronchodilation or provocation. The bronchodilation test are people with obstructive pattern in which you want to check if it can be reversed with the taking of aerosols. Provocation tests are performed when forced spirometry is normal but is suspected of having isolated obstruction episodes.

When doing a spirometry

Spirometry he is recommended to everyone that a lung disease, both to diagnose it and to monitor its evolution is suspected. Diseases that benefit most from a spirometry are:
COPD: chronic obstructive pulmonary disease appears in smokers long time evolution. There are two variants: emphysema and chronic bronchitis, although they overlap sometimes. Spirometry can detect the obstructive pattern, check that it not reversed with bronchodilators, and watch the evolution of the disease.
Asthma: asthma is another obstructive disease of the respiratory system, but this time is reversible with bronchodilator aerosol. It can be persistent and last a lifetime, or be related to allergies and more temporary.
Allergies: there are allergic substances that have a direct effect on bronchial lung, making that they block temporarily. One of the most common would be the seasonal allergy to pollen or grass.
Pulmonary fibrosis: it's a disease with a strong genetic component and whose origin is not clear. Appears in the middle ages of life, when suddenly the lung begins to fibrosarse. Spirometry detects a restrictive pattern.
Sarcoidosis: is an autoimmune disease that affects the lungs and other organs in the body. Internal Granuloma obstructing the bronchi are formed. Spirometry serves to define the degree of involvement.
Bronchiectasis: are specific lung lesions that produce a (sometimes huge) dilation of the bronchi. Spirometry is usually not the definitive diagnostic test, but you can find inconclusive changes that encourage them to perform more tests.

Preparation for Spirometry

If you are performing a spirometry these are the issues that you must take into account:
Duration: usually takes very little time, about 10 minutes.
Admission: admission is not needed, it can be done on an outpatient basis.
Is necessary to be accompanied?: not, is a painless and not invasive, so you can only attend the clinic and return in the same way.
Drugs: don't need to take any prior medication. You must tell your doctor all the medicines that you eat so that you assess whether you should keep them or leave them. Especially if they are bronchodilators in spray.
Food: you can eat normally, it is not necessary to go on fasting to the clinic.
Clothes: you can wear normal street clothes. When you do the test take off sweaters or jackets that can bother you when you want to expand the lungs to inspire.
Documents: is better to carry the medical steering wheel with which calls for testing and health card. Maybe give you the results at the time of completion of the test and you need to save them.
Pregnancy and breast-feeding: neither pregnancy nor lactation are contraindications for performing this test.
Contraindications: No.

How spirometry

When you are in the query they will make you a few general questions about your state of health and the situations in which you have noticed difficulty breathing. You will also be asked if you have repeat cough, expectoration, or heard ringing in the chest. Just after you explore, paying special attention to the auscultation of the lungs. If the doctor considers it necessary it will ask for Spirometry, which may make you at that moment or another day.
In the appointment of spirometry ask you that you feel and get comfortable. Advantage to take off your coats and jackets that make you feel uncomfortable when performing the test. When you're seated they ask that you take a small (somewhat larger than a mobile phone) device that has a small disposable tube. You will have to get the tube into the mouth to breathe through it. They tend to get pliers on the nose so that you breathe through it.
Prepared once they ask you that you breathe normally through the tube. So you will see that the machine well captures your breath and you breathe without problems. They will measure the air that you exchange through a normal respiratory rate. Then they ask you to take all the air you can and sewing it and sustain it for a few seconds, they will then tell you that you release it slowly until you can not already breathe more.
Here would be the simple spirometry. The next phase of the test would be forced spirometry. You will be asked to take all the air you can once again and sustain it for a couple of seconds. Then ask you that you let go of it suddenly, abruptly, and you keep releasing air until you can no more. It is normal that the technician who test yell and encourage you to release all the air quickly, sometimes with violence. It is the way that you see forced to perform the test properly, and if it doesn't you will have to repeat this last phase.
In cases where the obstructive pattern is detected, you can take the test of bronchodilation. This will give you a spray so you inhale a substance bronchodilator in two doses. A little while you repeat the forced spirometry.
Immediately after the test results, are obtained even if you have to go back to the doctor so that you assess them and you report.

Complications of spirometry

Spirometry complications are not known. It is a safe test that does not entail risks for persons who are subjected to it. Associated with the test, have described asthma attacks but it is anecdotal and they can be prevented by detecting people who are not well respiratoriamente at the time of the test.


The spirometry results are obtained at the same time make it and must be performed by a pulmonologist or doctor with experience. In the report, there will be a series of data that help to understand what kind of alteration of lung function you have.
The values that they are obtained from the simple spirometry are:
Current volume: is the volume of air that we exchange with normal breathing. It is usually 0.5 l.
Inspiratory and expiratory reserve volume: is the volume of air that can inspire or breathe if we force the breath the most. We can come to inspire 3 more L & 1.1 L more than normal.
Vital capacity: is the sum of the current volume + inspiratory reserve volume + expiratory reserve volume. It is therefore the entire volume of air that can drop from a maximum inspiration.
What we can not study with a spirometry is the total lung capacity, i.e., the total volume of air that are capable of retaining the lungs. This happens because always remains something of air in the lungs even when we perform a maximum exhalation is the residual volume.
The values that they are obtained in a forced spirometry are:
Forced Expiratory Volume in one second (FEV1 or FEV1): is the volume of air that we are able to expel from blow in the first second of expiration.
Forced vital capacity (FVC or FVC): is the time it took us to expel all possible air from a maximum inspiration
Tiffeneau index: is obtained by dividing the FEV between the FVC. Thus it is known what percentage of volume is ejected in one second with respect to the total volume of air. It is the most important value because it allows to classify obstructive or restrictive pulmonary pattern . The normal value is 80%.
Forced expiratory flow between 25-75% of the FVC: is a value that has a complicated interpretation. It is the first to be altered in smokers and can detect if in the future there will be a serious pulmonary obstruction.
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