Spirometry

2024 Author: Rachel Wainwright | [email protected]. Last modified: 2023-12-15 07:39

Spirometry is a ventilation test that is used to diagnose the condition of the respiratory system. Spirometry makes it possible to measure the volume of the respiratory system, the volumetric air flow rate and their ratio, the vital capacity of the lungs, the capacity of the outlet and inlet, and maximum ventilation.

Spirometry makes it possible to identify lung diseases and cardiovascular pathologies, assess their severity, and the effectiveness of treatment. In addition, the test helps to learn how to breathe correctly.

It is believed that smokers need to undergo spirometry annually: the examination will help to identify pulmonary dysfunction at an early stage, to carry out differential diagnosis of bronchial asthma, obstructive chronic pulmonary diseases, sarcoidosis.

This diagnostic method has no contraindications, including age restrictions: spirometry is performed in children and adults.

The procedure for conducting an examination with spirometry

Spirometry is performed using a special device for continuous graphic recording of changes in the volumes of exhaled and inhaled air - a spirograph. A new disposable mouthpiece is put on the device for each patient.

The subject is asked to take a very deep breath, hold his breath, press his mouth as tightly as possible to the mouthpiece (from this moment, the recording on the device begins) and evenly and calmly exhale all the collected air. In patients with chronic obstructive pulmonary disease, this may take about 15 seconds. After a calm exhalation, the patient needs to do the same, but make maximum effort.

The patient repeats this procedure two more times, and the doctor uses the obtained three groups of indicators to decipher the spirometry.

Spirometry indicators

Spirometer - a device for conducting spirometry

Most spirometry indicators are expressed as a percentage of the average physiological values. The rate ranges from 80-120%. In the decoding of spirometry, you can find the following indicators:

tidal volume - the volume of air entering the lungs in one breath with a calm exhalation. The norm is 500-800ml;
VC - vital capacity of the lungs - the volume of the lungs that comes out when you exhale. This indicator is significantly reduced in restrictive lung diseases;
FZhEL1 - forced vital capacity of the lungs. This indicator of spirometry is similar to the previous one, but the patient must exhale at the highest possible speed and with the highest possible effort.
FEV1 - forced expiratory volume in 1 second. The amount of air that leaves the lungs in the first second of exhalation, with maximum effort. These spirometry data in children and adults reflect the state of the large airways, expressed as a percentage of the vital capacity of the lungs. The forced expiratory rate is 75%.
Tiffeneau's index. The percentage of FEV1 to FVC. Its rate is 70% or more.
Average volumetric velocity. Measured as a percentage - 25-75%. Shows the state of the small airways. The volumetric velocity is useful for detecting early obstructive disorders.
Expiratory flow peak. The maximum speed that a person can show with increased exhalation.
Airway patency. Depends on muscle effort, displays the state of the airways at the level of large bronchi, trachea.

Since all these indicators are taken from the patient three times, when decoding spirometry, the doctor takes the best result for analysis and compares it with the norm indicators for the corresponding group of people: the patient's height, gender, and age are taken into account.

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