Pulmonologists (specialists in pulmonary medicine) have various methods at their disposal for diagnosing and determining the type of asthma. In addition to a detailed discussion of the patient's medical history (anamnesis), these include physical examinations, allergy tests, various lung function tests, chest imaging procedures such as ultrasound, X-ray, CT, MRI, and blood tests.
Permanent monitoring of the disease is at least as important as the correct diagnosis. Follow-up is extremely important and requires the active cooperation of the patient. Between regular check-ups with a specialist, asthmatics should take measurements on their own and document not only the measured values but also the effects of the symptoms on their daily life. This allows doctors to assess how the illness is progressing and adjust the asthma therapy accordingly.
From diagnosis to individual asthma therapy
If you experience breathing difficulties, you should not delay a visit to your doctor unnecessarily. Because especially if you suspect you might have asthma, the same applies as with all illnesses: namely that the sooner you get a diagnosis and appropriate treatment is prescribed, the better your chances of getting a handle on the symptoms and containing the progress of the disease over time.
Anamnesis and physical examination
A good doctor-patient relationship is built on trust, and this starts with a detailed medical consultation. This provides doctors with extensive information about the symptoms and the progression of the disease to date. In the course of the conversation, your doctor is likely to ask questions such as whether you smoke or practice sports, whether you have a family history of respiratory diseases, whether you have any allergies, at what time of day the symptoms occur and how they present, or whether the symptoms are more severe in certain situations.
During the consultation, your doctor will be looking out for typical signs of asthma, for example a pale complexion or a bluish discoloration of your fingers and lips, which indicate an oxygen deficiency.
During the subsequent physical examination, your doctor listens to your lungs with a stethoscope and watches out for typical breathing sounds caused by the asthma. Tapping the chest also provides doctors with information about the condition of the lungs. The resulting percussion sound allows them to draw conclusions about the volume of air and any fluid accumulation in the lungs.
Since lung diseases can also have a negative effect on the heart, your doctor will listen to your heart murmurs through a stethoscope and may even record an electrocardiogram (ECG).
Since in most cases asthma develops as a result of an allergy, it makes sense to have your doctor perform an allergy test. This identifies which substances you show an allergic reaction to, because they can trigger an asthma attack. Knowing which substances you are allergic to also makes it easier to avoid them as far as possible.
Lung function tests by a specialist
Extensive pulmonary function tests are usually performed by a specialist. Compared to the home methods of daily monitoring, professional measuring devices at the doctor's practice offer more extensive and accurate diagnostic possibilities.
Various lung function tests can be used to measure how well your lungs are currently performing, and clearly identify restrictions in lung function. All of the test procedures are non-invasive. This means that they do not require any medical interventions such as incisions or pricks.
Spirometry – small lung function test
In spirometry, lung function is tested using a spirometer, a device that measures the volume of inhaled or exhaled air. This provides important parameters for assessing the course and severity of the asthma.
At the beginning of the examination the patient puts on a nose clamp, which prevents breathing air from flowing past the spirometer. Then the patient breathes in and out through a mouthpiece as instructed by their doctor or practice staff. This provides a snapshot of the current lung function.
During the measurement, important parameters are checked to assess the performance of the lungs and airways:
- The amount of air that can be inhaled and exhaled during normal respiration (respiratory flow volume)
- The volume of air that can be additionally inhaled and exhaled after a normal breath with maximum effort (lung reserve volume)
- The available volume of the lung, i.e. the sum of the air volume of a normal breath plus the additional volume when breathing in and out with maximum effort (lung vital capacity)
- The amount of air that can be exhaled within one second after maximum inhalation (FEV1 value)
- The volume that can be inhaled and exhaled over a period of time (flow-volume curve)
- The measured values are compared with defined standard values. These norm values depend on age, height, and gender.
To avoid measurement inaccuracies, it is vital that patients cooperate and follow their doctor's instructions to the letter.
Bronchospasmolysis test for diagnosis confirmation
In many cases, after administering asthma medication to dilate the airways, a second measurement is taken to check the diagnosis. A bronchospasmolysis test is used to determine whether the constriction can be reduced through medication. Significantly improved measured values are seen as a confirmation of the asthma diagnosis.
Body plethysmography – large lung function test
In this lung function test, the patient sits in a special sealed glass cabin. This supplements spirometry by determining the complete lung volume and airway resistance. The respiratory values are determined indirectly via the change in pressure in the glass cabin, making the measured values less dependent on motivation and forced exhalation than in spirometry. This provides the physician with further diagnostic information especially for patients who have difficulties in performing spirometry.
A further advantage of this examination method is that it allows both the degree of airway constriction and the decrease in the elasticity of the lung tissue to be measured in a differentiated manner. This enables the physician to determine the type of respiratory disease more precisely and to make a reliable statement about the severity and course of the disease.
As a newer, additional diagnostic method, especially in early detection, measurement of the nitric oxide (NO) concentration in the exhaled air is carried out to confirm a suspected diagnosis of allergic or so-called type 2 asthma, and to monitor progress. NO measurement is a standardized diagnostic procedure that is also used for asthma control and monitoring of asthma therapy.
NO measurement is easy, fast, and requires very little effort on the part of the patient, who merely breathes into a special analyser for a few seconds. This device measures the fractional exhaled nitric oxide (FeNO), which allows existing inflammatory processes in the airways to be assessed. The more pronounced the inflammation, the higher the concentration of NO is in the exhaled air. Before NO diagnostic devices were introduced, the inflammatory state of the airways could often only be determined by bronchial lavage (flushing) of the bronchi or by sputum analysis. Both procedures are complex and usually unpleasant for the patient, and are only used in a few practices or clinics.
In addition to receiving a reliable diagnosis, doctors can also adjust the asthma therapy directly to reflect the degree of inflammation, enabling them to fine tune drug dosage and minimize side effects. Whereas in the past NO measurement was only carried out by specialist institutions and doctors, the home measuring device now provides a piece of equipment that allows patients to carry out FeNO measurement at home themselves.
Stress or provocation test
Particularly with allergic asthma or exercise-induced asthma, patients are often free of symptoms when they visit their doctor. Accordingly, lung function tests do not show any particular abnormalities. In such cases, physicians have the possibility to deliberately trigger the narrowing of the airways through different stimuli, e.g. physical stress or inhalation of histamine, in order to test the level of irritability in the airways (hyperreactivity or hyperresponsiveness) also in symptom-free periods.
Regular asthma monitoring by the patient
Monitoring the degree of inflammation with FeNO home measurement
Measuring the FeNO value in exhaled air provides information about the allergic inflammation of the airways and is used by doctors as a supplementary diagnostic procedure to confirm the diagnosis. Until recently, the FeNO value had to be checked by a physician. Now, with , asthmatics have a modern and easy-to-use device at their disposal, which allows them to measure their FeNO value for follow-up monitoring from the comfort of their own home or even when traveling. It determines the in the exhaled air in a matter of seconds. The device immediately displays the current degree of inflammation, classified according to a traffic light system. This enables patients to better gauge the current inflammatory state of their airways and to adapt their daily routine perfectly to the exigencies of the disease.
Regular monitoring of the FeNO value provides primary care physicians with important information for asthma therapy and follow-up. Because medication can now be administered at the right time in the optimum dosage, even before acute symptoms occur.
In combination with the , asthmatics now also have the possibility to keep an electronic asthma diary. This eliminates the bothersome task of entering measured values in analog charts and makes it easier for asthmatics to manage their illness in line with the times.
Measuring peak flow with the peak flow meter
The peak flow meter is a handy device with which asthmatics can perform a simple lung function test at home. Peak flow measurement provides information about the degree of bronchial constriction. It measures the velocityat which air is exhaled from the lungs. The patient takes a deep breath and then blows as hard as possible into the peak flow meter. This determines the peak flow of the exhaled air. The more constricted the bronchial tubes are, the slower the air flows out of the lungs. The peak expiratory flow (PEF) is a comparative value that relates the current value to the personal best value. Fluctuations are recorded by measuring once or several times a day. Declining values and increased symptoms indicate that the asthma status has worsened. Keeping a peak flow log gives both patient and doctor an overview of the changes during the course of the day. When kept over a longer period of time, the log also provides information about the course of the disease as a whole. The disadvantage of this measurement is that the extent of the inflammation when asthma is present can only be assessed indirectly. Comparability of the individual measurements depends strongly on correct operation of the peak flow meter and the patient’s cooperation. Ideally, peak flow measurement should be supplemented by FeNO measurement in order to determine an inflammatory event earlier and more accurately.
It is important for asthmatics to actively control and manage the disease. The Asthma Control Test shows whether you are doing this to a sufficient extent. With the help of a few questions you can find out whether you have your asthma under control. The results are also important for your doctor, who can adjust your treatment if necessary. You can find the test on the website of the Deutsche Atemwegsliga e.V. ().