Diagnosis of asthma
Diagnosis of asthma is usually not difficult. Most often, it is enough to conduct an accurate interview with the patient. The doctor has to ask the patient very carefully about all the details that accompany the attacks of dyspnoea. The next is the auscultation of the lungs and the heart, sometimes it also takes blood for laboratory tests.
The basic test for the diagnosis of asthma is the lung function test using a spirometer.
The apparatus during the examination registers the efficiency of the bronchi and lungs based on inhalation and exhalation.
During the spirometry test, two basic quantities are measured: the first is the so-called life capacity. It is the amount of air that a patient can blow out of the lungs after having been given a deep air refill. During this measurement, you breathe slowly, evenly, but as deeply as possible. The second largest is the so-called first-second volume, i.e. the amount of air that a patient is able to remove from the lungs during the first second of the exhalation. With this measurement, it is necessary to exhale as quickly and as quickly as possible.
In the diagnosis of asthma, the first-second volume is mainly helpful. It is obvious that through the narrowed bronchi, there will be not enough air in a second, as well as healthy. The volume of air that exits the lungs during the first second expiration in asthmatics is much smaller than in a healthy person.
The suspicion of asthma can be confirmed by the so-called diastolic attempt. Assuming after the preliminary examination that the bronchi are constricted, inhaled beta-metabolism is given and the test is repeated after 10-15 minutes. If the first-second volume increased by at least 15% compared to the first study, it means that there was a typical bronchial spasm that persisted after the drug administration.
In specialized clinics, there are devices for more accurate and comprehensive lung function measurements. One of them is the so-called full body plethysmograph. With the help of the technique based on placing the examined person in a booth resembling a telephone booth, there is, among others, measuring the so-called breathing resistance, that is, the resistance that are the bronchi for air flow into the lungs.
Sometimes blood is collected from the earlobe or from the artery. This allows you to measure the content of oxygen and carbon dioxide in the circulating blood. The ratio of oxygen to carbon dioxide in the blood gives the doctor additional information on the limitation of gas exchange between the lungs and the external environment.