How breathing function and the condition of the respiratory system are checked

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Why the lungs need to be checked

The lungs work constantly, supplying the body with oxygen and helping remove carbon dioxide. As long as breathing is not impaired, people rarely think about how complex this system is. But cough, shortness of breath, wheezing, chest pain, sputum, reduced exercise tolerance or frequent infections may indicate that the respiratory system needs evaluation.

Lung examination helps not simply to “check if everything is normal.” Its task is to understand where exactly the problem occurs: in the bronchi, lung tissue, alveoli, pleura, pulmonary vessels, respiratory muscles or even outside the respiratory system. Sometimes shortness of breath is not related to the lungs, but to the heart, anemia, metabolic disorders, anxiety or a combination of several causes.

It is important not to wait for severe symptoms. Many respiratory diseases develop gradually. In asthma, symptoms may appear in attacks and disappear between episodes. In COPD, lung function declines over years, while a person gets used to shortness of breath and simply starts moving less. In chronic cough, the cause may be hidden in the bronchi, nasopharynx, allergy or reflux.

Timely diagnosis makes it possible to detect disease earlier, assess the degree of impairment, choose the right approach and monitor changes over time. This is especially important for smokers and former smokers, people with asthma, COPD, allergy, chronic cough, frequent bronchitis and reduced stamina.

Where examination begins

Lung examination begins not with a device, but with a conversation. The doctor clarifies which symptoms are present, when they appeared, how they changed over time, and whether there is a connection with exertion, time of day, season, infections, allergens, smoking, work, body position or medication use.

For example, shortness of breath with physical activity may point to COPD, asthma, heart causes, anemia or low physical fitness. Night cough may be related to asthma, postnasal drip, allergic rhinitis or reflux. Morning cough with sputum in a smoker may be a sign of chronic bronchitis or COPD.

The doctor also assesses risk factors: smoking, passive smoking, vapes, occupational dust, chemical substances, mold, animals, allergies, previous infections, chronic heart and lung diseases, diabetes, kidney disease, immunodeficiency and family history.

Examination includes assessment of general condition, respiratory rate, pulse, blood pressure, temperature, skin color, swelling, use of additional breathing muscles and the ability to speak without shortness of breath. These simple signs help understand how urgent the situation is.

Listening to the lungs

Auscultation, or listening to the lungs, remains an important part of examination. With a stethoscope, the doctor evaluates how air passes through the airways and whether crackles, wheezing, reduced breath sounds, crepitation or other changes are present.

Wheezing may point to narrowing of the bronchi. This occurs in asthma, COPD, bronchospasm after infection or other conditions with impaired bronchial patency. Moist crackles may be related to sputum, inflammation, congestion or infection.

Reduced breath sounds may occur with emphysema, pleural effusion, pneumothorax, pronounced obstruction or other conditions. Crepitation may appear when the alveoli or lung tissue are affected, for example in pneumonia or some interstitial lung diseases.

However, it is important to understand that normal auscultation does not always exclude disease. In asthma, the lungs may sound normal between attacks. In early COPD, changes may be minimal. Some diseases require additional methods because a stethoscope does not fully show breathing function or lung structure.

Pulse oximetry

Pulse oximetry is a simple method for measuring blood oxygen saturation. A small sensor is placed on a finger and shows oxygen saturation and pulse. The test takes a short time and does not require a skin puncture.

Oxygen saturation helps assess how effectively the lungs oxygenate the blood. This is especially important with shortness of breath, pneumonia, asthma or COPD exacerbation, severe infection, suspected respiratory failure, in older adults and patients with chronic diseases.

Low oxygen saturation may indicate impaired gas exchange and the need for closer evaluation. In some cases, oxygen support or urgent treatment is required. But normal oxygen saturation does not always mean there is no problem. For example, in mild asthma, early COPD, anemia, anxiety or cardiac causes of shortness of breath, saturation may remain normal.

Saturation should always be assessed together with symptoms. Respiratory rate, pulse, temperature, blood pressure, skin color, mental state, chest pain, severity of shortness of breath and overall condition all matter.

Spirometry

Spirometry is one of the main methods for assessing breathing function. It shows how much air a person can inhale and exhale, and how quickly air leaves the lungs. This is especially important when asthma, COPD and other diseases with airway narrowing are suspected.

During the test, the patient takes a deep breath and then exhales as quickly and forcefully as possible into a special device. Sometimes the maneuver is repeated several times to obtain a reliable result. The test requires correct performance, so explanation and supervision by a specialist are important.

Spirometry helps detect obstruction — a situation in which air has difficulty leaving the lungs because the airways are narrowed. Obstruction is typical of COPD, asthma and some other conditions. Spirometry may also show a restrictive pattern, when lung volume is reduced, but additional tests may be needed to clarify the cause.

The main value of spirometry is that it objectively shows breathing function. A person may get used to shortness of breath and consider it normal, but the test helps show how much airway patency is actually impaired.

Main spirometry parameters

Several parameters are assessed during spirometry. One of them is the forced expiratory volume in one second. It shows how much air a person can quickly exhale during the first second after a full inhalation. This parameter is especially important in obstruction.

Forced vital capacity is also assessed — the total volume of air that a person can exhale after a deep inhalation with maximum effort. Comparing these parameters helps understand whether there is airflow limitation.

If air leaves the lungs slowly and part of it remains trapped, this may indicate narrowing of the bronchi. In COPD, such limitation is often persistent. In asthma, it may be variable and partially or significantly reversible.

Spirometry results are compared with expected values for age, sex, height and other parameters. Therefore, it is important not to interpret one number independently. The whole protocol, test quality, symptoms and clinical situation matter.

Bronchodilator test

Sometimes spirometry is performed before and after inhalation of a bronchodilator — a medication that widens the airways. This helps assess how reversible bronchial narrowing is.

If values improve noticeably after a bronchodilator, this indicates that the bronchi are able to expand. Such reversibility is often typical of asthma, although it may also occur in other conditions. In COPD, obstruction is usually more persistent, but some patients may also have a partial response.

The bronchodilator test helps the doctor distinguish different causes of shortness of breath and cough, but it is not the only diagnostic criterion. Symptoms, medical history, triggers, smoking, allergy, age at onset and progression also matter.

It is important to prepare correctly for the test if the doctor asks the patient to temporarily avoid some inhaled medications before testing. But treatment should not be stopped independently — preparation depends on the purpose of the examination and the patient’s condition.

Peak flow monitoring

Peak flow monitoring measures peak expiratory flow using a small device. This method is most often used for asthma monitoring, especially if symptoms change, depend on triggers or asthma control needs to be assessed.

The patient may measure the value at home in the morning and evening, as well as when feeling worse. If values drop, this may be an early sign of bronchial narrowing even before a pronounced attack. A peak flow diary helps reveal fluctuations in breathing.

The method is useful when occupational asthma is suspected. If values worsen on working days and improve during weekends or vacation, this may point to a connection between symptoms and the work environment.

Peak flow monitoring does not replace full spirometry, but it may be a useful monitoring tool. It is especially helpful when the patient already knows their usual values and can compare them with the current condition.

Chest X-ray

Chest X-ray helps assess lung tissue, heart size, pleural spaces and some changes in the chest. It is often prescribed when pneumonia, prolonged cough, chest pain, fever, shortness of breath or unusual symptoms are suspected.

In pneumonia, an X-ray may show an area of inflammatory consolidation. It may also reveal fluid in the pleural space, some tumor processes, pronounced lung changes, consequences of previous diseases or signs of heart failure.

However, X-ray does not show everything. Some early or small changes may be invisible. X-ray also does not assess breathing function the way spirometry does. Therefore, a normal X-ray does not exclude asthma, early COPD, bronchial hyperreactivity or some other causes of shortness of breath.

X-ray is part of diagnosis, not a universal answer to all questions. Its meaning depends on symptoms, examination, tests and the suspected diagnosis.

Computed tomography of the lungs

Computed tomography, or CT, gives a more detailed image of the lungs, bronchi, pleura, vessels and chest structures. It may be needed if X-ray is not informative enough, symptoms persist, the disease course is unusual or more complex changes are suspected.

CT may help detect interstitial lung diseases, bronchiectasis, emphysema, tumors, pneumonia complications, pulmonary embolism with special contrast imaging and other conditions.

Not every patient with cough or shortness of breath needs CT. The method is used when indicated, because it involves radiation exposure and should answer a specific diagnostic question. In typical situations, examination, spirometry, X-ray and blood tests are often enough.

If CT has already been performed, its results should be interpreted together with the clinical picture. Small findings do not always explain symptoms, and sometimes significant functional impairment may require additional testing even if the image looks relatively calm.

Blood tests

Blood tests help assess the body’s condition and possible causes of respiratory symptoms. With cough, fever and suspected infection, markers of inflammation may be checked. With shortness of breath, it is important to exclude anemia, because with low hemoglobin tissues receive less oxygen even if the lungs are working normally.

Kidney function, electrolytes, markers of cardiac strain, markers of heart muscle injury, glucose levels, thyroid function and other parameters may also be assessed. This is especially important if shortness of breath may be related not only to the lungs.

With allergic symptoms, specific IgE tests or other allergy investigations may be used. But results should be interpreted together with symptoms: a positive test does not always mean that this exact allergen is causing the complaints.

Blood tests do not replace examination and lung function testing. They help show the overall picture and exclude conditions that may mimic respiratory problems.

Sputum testing

Sputum testing may be needed with prolonged productive cough, suspected bacterial infection, tuberculosis, bronchiectasis, unusual disease course or lack of improvement with treatment. Sputum may provide information about the character of inflammation and possible pathogens.

It is important to distinguish sputum from saliva. The sample should be sputum from the airways, not material from the mouth. Therefore, patients are sometimes instructed how to collect the sample correctly.

With ordinary viral bronchitis, sputum testing is usually not required. But with chronic cough, abundant sputum, blood, unpleasant smell, frequent infections or immunodeficiency, it may be useful.

Sputum test results should also be interpreted carefully. Different microorganisms may be present in the airways, and not every detected microbe is necessarily the cause of disease. The decision depends on symptoms, inflammation, imaging findings and the patient’s condition.

Allergy testing

If symptoms are related to season, pollen, dust, animals, mold, the work environment, itching, sneezing, rhinitis or asthma, allergy testing may be needed. It helps understand which allergens may truly provoke airway inflammation.

Skin tests or blood tests for specific IgE may be used. The choice depends on age, skin condition, medications being taken, symptom severity and test availability.

It is important to remember that an allergy test does not answer every question. A positive result shows sensitization, meaning an immune response to an allergen. But to understand whether it causes symptoms, the result must be compared with the real pattern: when complaints appear, where they worsen, whether there is seasonality and contact with the allergen.

Allergy testing is especially useful in allergic rhinitis, asthma, chronic cough, seasonal symptoms and suspected occupational factors.

Bronchoscopy

Bronchoscopy is a procedure in which a doctor examines the airways from the inside using a special instrument. It is not used for every patient with cough, but only when there are specific indications.

Bronchoscopy may be needed with coughing up blood, suspected tumor, foreign body, bronchial narrowing, unusual infections, the need to take material for analysis or to clarify the cause of CT findings.

The procedure allows the doctor to examine large bronchi, take sputum samples, washings, biopsy or remove a foreign body in certain situations. It is a more invasive method, so it is prescribed when the benefit of the information outweighs possible discomfort and risks.

For most common causes of cough and shortness of breath, bronchoscopy is not the first step. Usually, the process begins with examination, spirometry, X-ray, blood tests and other less invasive methods.

Blood gas analysis

With severe shortness of breath, low oxygen saturation, COPD, suspected respiratory failure or severe pneumonia, blood gas analysis may be needed. It shows the levels of oxygen, carbon dioxide and acid-base balance.

This test helps understand how effectively the lungs perform gas exchange. Carbon dioxide level is especially important because in some diseases it may accumulate in the blood. This may be dangerous and requires a special treatment approach.

Blood gas analysis is more often performed in hospital settings or in severe illness. It is not needed for every cough or mild shortness of breath, but it may be critically important in pronounced respiratory failure.

The results help doctors decide whether oxygen support, non-invasive ventilation, intensive monitoring or a change in treatment is needed.

Heart examination in shortness of breath

Shortness of breath is not always related to the lungs. Heart failure, coronary artery disease, rhythm disturbances, valve diseases and high blood pressure may cause lack of air, especially during exertion or when lying down.

Therefore, with shortness of breath, heart evaluation is often required. This may include ECG, echocardiography, blood tests, Holter monitoring, exercise tests or other methods. It is especially important to examine the heart if there is leg swelling, nighttime shortness of breath, chest pain, palpitations, hypertension, diabetes or a previous heart attack.

The lungs and heart work together. If the heart pumps blood poorly, congestion may occur in the lung vessels. If the lungs oxygenate blood poorly, the load on the heart also increases. Therefore, symptoms often require comprehensive evaluation.

Not every shortness of breath should automatically be considered “pulmonary.” The correct diagnosis depends on comparing respiratory, cardiac, laboratory and functional data.

When examination is needed urgently

Some symptoms require urgent medical help. These include sudden or rapidly increasing shortness of breath, difficulty breathing at rest, inability to speak in full sentences, blue lips or fingers, confusion, fainting, severe chest pain, coughing up blood or pronounced weakness.

Urgent care is also needed with low oxygen saturation, a severe asthma attack, COPD exacerbation, suspected pneumonia with worsening condition, sudden chest pain during breathing or shortness of breath after prolonged immobility, surgery, flight or trauma.

In such situations, examination is aimed not only at finding the cause, but also at quickly assessing a life-threatening condition. ECG, blood tests, X-ray, CT, blood gas analysis, oxygen support and monitoring may be needed.

If a symptom appears suddenly and the condition is severe, one should not wait for a scheduled appointment. Respiratory failure may develop quickly, especially in older adults and patients with chronic diseases.

Who especially needs lung function testing

Spirometry and lung assessment are especially important for people with chronic cough, sputum, shortness of breath with exertion, wheezing, frequent bronchitis, recurrent pneumonias or prolonged recovery after infections.

Smokers and former smokers are a group in which COPD should not be missed. Even if a person considers cough familiar, spirometry may show airflow impairment before severe shortness of breath appears.

In people with asthma, examination helps assess disease control, confirm diagnosis, choose an approach and monitor changes. If symptoms persist despite treatment, not only medications but also inhaler technique, triggers, allergy, rhinitis and possible comorbid causes should be checked.

Workers exposed to dust, chemical substances, smoke, aerosols, flour, animals or other occupational irritants may also need respiratory evaluation, especially if symptoms worsen at work.

Why one test is often not enough

Respiratory symptoms may have several causes at the same time. For example, a person may have asthma and allergic rhinitis, COPD and heart failure, chronic cough due to reflux and postnasal drip, or shortness of breath caused by anemia and low physical activity.

Therefore, one normal test does not always close the question. A normal X-ray does not exclude asthma. Normal saturation does not exclude anemia or cardiac shortness of breath. Normal spirometry between attacks does not always exclude bronchial hyperreactivity.

Diagnosis is built like a puzzle. The doctor compares complaints, examination, spirometry, imaging, blood tests, risk factors, symptom dynamics and response to treatment. Only in this way can the main mechanism be understood.

That is why it is important not simply to “do every test,” but to choose examinations according to the clinical question. The right question helps choose the right method.

How to prepare for a visit

Before a visit, it is useful to remember when symptoms appeared, what worsens or improves them, and whether there is a connection with exertion, nighttime, season, work, animals, dust, food, body position or infections. These details are often more important than they seem.

It is useful to write down how often cough or shortness of breath occurs, whether there is sputum and what it is like, whether wheezing, fever, chest pain, blood in sputum, leg swelling, palpitations, weakness or weight loss occur.

It is important to bring a list of medications, including inhalers, blood pressure medications, painkillers, hormonal medications, supplements and remedies the person uses independently. Some medications may affect cough, breathing or test results.

If X-rays, CT scans, spirometry, blood tests or hospital discharge reports have already been done, it is useful to bring them. Comparing old and new data helps assess dynamics.

Examination as part of prevention

Lung checks are needed not only when disease is already pronounced. In people with risk factors, examination helps detect problems earlier. This is especially important with smoking, occupational exposures, chronic cough, allergy, asthma and recurrent infections.

Spirometry may detect reduced breathing function before a person starts experiencing serious limitations. Early diagnosis of COPD, for example, makes it possible to quit smoking in time, begin monitoring, select treatment and reduce the risk of exacerbations.

In asthma, assessment of breathing function helps prevent getting used to symptoms. If a person often coughs at night, limits activity or regularly uses quick-relief medication, this may mean insufficient disease control.

Lung examination is a way to understand how the respiratory system works and notice changes in time. Spirometry, pulse oximetry, X-ray, CT, blood tests, allergy testing and other methods do not replace each other, but complement the overall picture. The more accurately the cause of cough, shortness of breath or reduced stamina is identified, the more correctly treatment, prevention and follow-up can be chosen.