Introduction
Bronchial asthma is a chronic inflammatory disease of the lungs. In bronchial asthma, the airways are reversibly constricted and hypersensitive. The symptoms may vary depending on the severity of the disease.
A compulsion to clear the throat, coughing or shortness of breath may occur. The more frequently these symptoms occur, the more severe the disease is. Various pulmonary function tests are available in order to make a final diagnosis.
The classification of bronchial asthma
According to the cause: The symptoms can be classified into the following degrees of severity of asthma brocnhiale according to the guidelines of the German Respiratory Tract League:
- Bronchial asthma: Intermittent (with interruptions) symptoms of asthma occur less than twice a week during the day and less than twice a month at night. In addition, the FEV (for explanation see diagnosis) is above 80%.
- Bronchial asthma grade: Persistent (permanent), mild symptoms occur on average less than once a day, which means that there are also days off within a week when one is symptom-free. The number of symptomatic nights increases to more than twice a month. In addition, FEV is still over 80%.
- Bronchial asthma: Persistent moderate symptoms occur daily, at night once a week. The FEV is between 60% and 80%.
- Bronchial asthma grade: Persistently severe symptoms are present continuously during the day, at night more than once a week, FEV is less than 60%.
- Allergic or extrinsic asthma
- Non-allergic or intrinsic asthma
- Hybrid forms
The diagnosis
A distinction is made between the diagnosis of an acute asthma attack and the diagnosis of asthma during the symptom-free interval. The acute asthma attack can be diagnosed by the characteristic symptoms as described above (shortness of breath, exhalation sounds, coughing, exhaustion). If the asthma symptoms described above occur, a physician should be consulted even if the symptoms appear to be asymptomatic.
The description of the typical symptoms usually results in the suspected diagnosis of asthma. The symptom coughing is less significant than, for example, the occurrence of whistling noises (stridor or wheezing). An important role in the diagnosis of asthma is played by lung function testing.
It comprises several tests, all of which are designed to determine whether the lungs are restricted in their function or whether they are functioning normally. Spirometry is important for assessing lung function. For the examination, the patient breathes through the mouth into the mouthpiece of a spirometer and the nose is closed by a nose clip.
The device measures the force with which the patient inhales and exhales and the amount of air moved. The device then displays the air quantities graphically as a curve. In addition to normal breathing, the device is also used to test how the values change at maximum inhalation and exhalation.
One of the most important values for the diagnosis of bronchial asthma is the one-second capacity, also known as FEV1 (forced expiratory (exhaled) volume in 1 second) or Tiffeneau test. In this procedure, the patient is asked to inhale as deeply as possible and then exhale as quickly and deeply as possible. The spirometer then indicates how much volume of the inhaled air has been exhaled within the first second.
In bronchial asthma, this value is lowered because the air must overcome greater resistance due to the chronic inflammation and narrowing of the airways. Even if this greater resistance is not noticed in the symptom-free interval, it can be measured with the spirometer. The peak flow measurement is particularly suitable for diagnosing the severity of an asthma attack.
The devices are very handy and can be used, for example, by an asthmatic at home for self-monitoring, which is why it is also called the “clinical thermometer of the asthmatic”. To measure the “peak-flow”, one also breathes through a mouthpiece, but here the peak-flow, i.e. the strongest airflow expelled from the lungs, is measured. It is not the volume that is moved, but the force with which the airflow escapes from the mouth.
If, as is typical for asthmatics, resistance in the bronchi must first be overcome, the strength of the airflow is reduced. Decreasing values therefore mean a worsening of the asthma. The metacholine provocation test is an inhalation provocation test.
This means that the substance metacholine is inhaled by the patient. The reaction of the airways to the methacholine is then evaluated.Metacholine is a drug that stimulates the parasympathetic nervous system. In existing asthma, the airways become even narrower than in healthy people and shortness of breath can result.
The test is evaluated by spirometry. The patient to be tested is administered the metacholine through a nebulizer. Afterwards values are measured, such as the one-second capacity or the airway resistance.
If these have exceeded a certain value, they are pathological. The suspected hypersensitivity of the airways can thus be confirmed. In addition to lung function, an allergy test should also be performed in the case of allergic bronchial asthma, e.g. by means of a prick test.
The prick test involves applying various liquids containing an allergen to the forearm (e.g. cat hair, birch pollen or rye flour). A tip is used to prick lightly into the skin covered by the solution. After some time, red swellings form if there is an allergy to the applied allergen.
In addition to the allergy test, a determination of the total IgE can be made. A significant increase in total IgE is considered an important indication of the presence of an allergic disease. In addition, one can specifically search for IgE antibodies directed against the suspected allergen. An x-ray of the thorax (chest) may be inconspicuous in the early stages of the disease, but in the acute stage of the disease it serves to exclude other diseases that may cause similar symptoms to asthma. If the disease persists for a longer period of time, conclusions can be drawn from the X-ray image as to possible tissue damage to the lungs.
