A lung function test can be performed even in young children and quickly leads the doctor to a reliable diagnosis of breathing problems or tightness in the bronchi. The pulmonary function test is performed primarily in specialized medical practices for lung and bronchial medicine (pulmonologist) but also by general internists or general practitioners.
What is a pulmonary function test?
The lung function test, also called spirometry, provides information about the current condition of both lungs and the bronchi within a few minutes. The pulmonary function test is used both for diagnosis and for monitoring the course and therapy of existing lung diseases. Depending on the existing clinical picture, patients may even have to undergo such a lung function test several times a week.
Function, effect, and goals
Whether a possible lung weakness is present, an already existing lung disease is progressing or has come to a standstill after all, can be interpreted reliably and quickly on the basis of the measured values of a lung function test. Depending on the sex, age and size of a patient, the lung function test provides individual information about the fitness and health status of the lungs. The measured values can be used to quickly determine whether, for example, years of inhaled smoking have already led to permanent damage to the lungs. The lung function test allows precise conclusions to be drawn about the course and stage of chronic lung diseases in particular, such as asthma, bronchitis or emphysema, on the basis of the values determined. The parameters of the lung function test can also be used to diagnose these diseases for the first time. Over the course of time, the medical industry has developed a wide variety of devices to enable a lung function test to be performed safely and easily. Simple spirometers for quickly checking the so-called vital capacity are just as much a part of this as technically sophisticated devices that outwardly resemble a telephone booth. As so-called bodypletysmography, this special and comprehensive pulmonary function test is reserved for larger pulmonary practices and medical centers. The lung function test is performed by connecting the patient to the spirometer through a mouthpiece. Nasal breathing is prevented by a special nose clip before the actual test is performed, so that the patient can actually breathe only through the mouth. Only when perfect test conditions have been created can the actual pulmonary function test begin. Calibration is therefore required for each measurement in order to calibrate the spirometer to the patient’s individual breathing rhythm. Special software detects irregularities and incorporates them later in the test evaluation, so that the physician always receives reliable readings. In various breathing maneuvers, the patient is instructed to breathe in and out deeply or even to hold his breath. In the process, the pulmonary function test measures both the volume and the force of the exhaled air. When the pulmonary function test is assessed, the ratio of two specific values is crucial. These are vital capacity and one-second air.
Risks, side effects, and hazards
Vital capacity is the maximum amount of air that can be exhaled after inhaling as deeply as possible. The term one-second air refers to a volume of air that can be forcefully exhaled within one second. The lung function test now uses these two parameters to determine the ratio of the individual one-second air value to the normal value of vital capacity for the corresponding age group and depending on gender and size. The lung function test gives the ratio of the two values as a percentage. The percentage value determined now only needs to be compared with the normal value table in order to make a reliable statement about a patient’s lung function. In accordance with the different lung capacities, the standard values for men and women are different in each case. In patients with chronic lung or heart disease, the lung function test is performed at regular intervals in consultation with the attending physician. During this therapy and progress control, the medication used in each case can also be constantly adjusted. The lung function test is therefore a very important tool for diagnosis and therapy in practice.The measured values are recorded in a patient diary. Patients with chronic lung diseases can also perform the lung function test at home on their own using a so-called peak flow meter. As soon as the measured values deteriorate, the physician must be consulted.
Typical and common lung diseases
- COPD (chronic obstructive pulmonary disease).
- Cough
- Lung cancer
- Pulmonary edema
- Pulmonary fibrosis
