Lung disease is considered an important disease because it greatly affects quality of life and is directly related to the respiratory system. Nowadays, Thai people face increasingly severe air pollution caused by natural environmental conditions, engine combustion releasing large amounts of carbon monoxide, smoking, or even epidemics and various infections. This has led to a rising trend in the number of patients. However, public awareness of the dangers of lung disease remains very low compared to heart disease, stroke, and cancer. For example, when experiencing a cough, people often buy medicine themselves or let it heal on its own, forgetting that the symptoms may be warning signs of a lung-related disease. If left unchecked and untreated properly, it may progress severely and become difficult to cure.
Do you know who is at risk of lung health damage?
Generally, we cannot know that our lungs are sick until symptoms appear, and by then the disease is often in an advanced stage because the lungs are known to be highly resilient and can hide symptoms for a long time. However, a test called “Pulmonary Function Tests (PFTs)” can help screen and detect hidden early symptoms. So, who should undergo this test?
- Smokers and those regularly exposed to secondhand smoke from people nearby
- People who regularly use public transportation or ride motorcycles
- People living in areas with high pollution, such as near industrial factories or major roads
- People with a chronic cough lasting more than 2 weeks
- People who get tired easily or feel shortness of breath
- People with respiratory system diseases such as allergic rhinitis, asthma, or emphysema
- People who work in highly polluted environments, such as factories with dust, mines, stone mills, chemical fumes, near busy roads, or those regularly exposed to cooking fumes
- People exposed to tuberculosis patients or have family members with tuberculosis
- General people who have no symptoms but have the risk factors mentioned above
What is Pulmonary Function Tests (PFTs)?
Pulmonary Function Tests (PFTs) are both screening and diagnostic tests, including evaluating treatment outcomes for respiratory diseases such as asthma, chronic obstructive pulmonary disease, and occupational lung diseases. The test results can indicate lung function deterioration before symptoms appear, such as unnoticed shortness of breath, but the test may reveal significant lung damage.
Pulmonary function testing requires the patient to blow air with maximal effort, both inhaling and exhaling through the mouth, which is unfamiliar to most people. A skilled and experienced technician will guide the timing of inhalation and exhalation, which is crucial for accurate test evaluation.
What is Spirometry Pulmonary Function Testing?
Spirometry uses a device called a Spirometer to measure the volume of air inhaled and exhaled from the lungs. The data is displayed as a graph showing the relationship between volume and time, called a Spirogram. The advantages of this method include:
- Using uncomplicated equipment, making it widely popular
- Easy to perform, taking only 15-30 minutes
- Provides reliable data with multiple measurable values that are very useful
Test result evaluation
Spirometry shows lung function values as follows:
1. FVC (Forced Vital Capacity)
is the volume of air forcefully exhaled after a full inhalation. FVC reflects the total volume of air in the lungs. This value decreases when lung tissue changes, such as fibrosis or incomplete lung expansion. This condition is called RESTRICTIVE, meaning limited lung expansion. The normal FVC value should be more than 80% of the expected volume.
2. FEV1 (Forced Expiratory Volume in one second)
is the volume of air forcefully exhaled in the first second. FEV1 is the most commonly used value in pulmonary function testing. It is used together with FVC to calculate the FEV1/FVC% ratio. The normal value should be more than 80% of the expected volume.
3. FEV1/FVC%
is the percentage of air exhaled in the first second relative to the total forced exhaled volume. This value best indicates airway obstruction. The FEV1/FVC% reflects the ability to exhale air from the lungs, depending on the patient’s effort and airway condition. If the airway is obstructed or less elastic, air passage is difficult, and the value decreases. This condition is called OBSTRUCTIVE, meaning airway obstruction or narrowing. The normal value should be more than 70%.
These three values indicate abnormalities in the respiratory system and lungs for disease prognosis and treatment evaluation, such as:
- Airway obstruction in asthma patients
- Emphysema caused by smoking
- Chronic bronchitis
- Reduced lung elasticity and capacity in lung tissue diseases
- Abnormal respiratory muscle or bone structure, or multiple combined diseases
Pulmonary function testing reveals the efficiency of the respiratory organs, especially the lungs, by measuring the volume of air entering and leaving the lungs, the size of the respiratory system, and oxygen levels. This differs from chest X-rays, which detect lung lesions. Pulmonary function testing is easy to perform but highly beneficial, capable of detecting abnormalities before symptoms appear. It serves as both prevention against disease progression before irreversible lung damage occurs and as part of treatment evaluation.