The initial suspicion of an interstitial lung disease is based on symptoms. Before the pulmonologist can diagnose pulmonary fibrosis, the patient must undergo several tests:
Detailed interview
A thorough and careful interview by the pulmonologist is crucial. Special attention is given to symptoms of shortness of breath and the physical activities the patient can still perform. Questions include:
- Current and past exposures to certain substances, gases, or vapours
- Hobbies
- Occupational activities
- Contact with animals (pets)
- Medication use
- Smoking habits
The family history is also reviewed to rule out hereditary disorders. Additionally, the presence of signs of underlying inflammatory diseases is assessed.
It’s important to note that pulmonary fibrosis is sometimes only detected years after exposure!
Physical examination
The pulmonologist inspects and palpates the chest and listens to the lungs with a stethoscope. The presence of crackles – a fine crackling sound similar to the opening of Velcro at the lung bases – may suggest this condition. The doctor also observes the breathing pattern and conducts a general physical examination to rule out other conditions or confirm underlying inflammatory diseases.
Clubbed fingers are present in 40-70% of patients with pulmonary fibrosis. Signs of systemic sclerosis may also be observed.
Blood tests
A comprehensive blood analysis is performed, as certain blood tests can indicate a specific disease causing pulmonary fibrosis, such as rheumatoid arthritis or systemic sclerosis.
Chest X-ray
A chest X-ray is one of the most important routine examinations for interstitial lung diseases and pulmonary fibrosis. Abnormalities are often visible, especially in the lower parts of the lungs.
High-resolution CT (HRCT) scan of the lungs
In recent years, HRCT scans have become essential for diagnosing pulmonary fibrosis and evaluating the degree and severity of the condition throughout its progression.
During the scan, the patient lies in a "large tube" that emits X-rays from different angles. The data is processed by a computer to generate images, providing a detailed view of changes in lung tissue.
Pulmonary function tests
- Spirometry and diffusion
Respiratory function tests assess lung performance. The patient breathes through a mouthpiece, while a clip prevents nasal breathing. The volume and speed of air inhaled and exhaled are measured. In pulmonary fibrosis, the total air volume exhaled is reduced, and the oxygen diffusion capacity is significantly impaired. - Arterial puncture
A blood sample is taken from an artery in the wrist. This measures the oxygen level in arterial blood to check if the lungs provide sufficient oxygenation. - 6-minute walk test
This test measures how far a patient can walk in 6 minutes, providing an indication of functional limitations.
Bronchoscopy and bronchoalveolar lavage (lung washing)
A bronchoscopy involves examining the airways with a bronchoscope, a flexible instrument equipped with a lens or camera. During this procedure, small lung tissue samples may be taken (biopsy), and mucus plugs can be removed.
To detect lung tissue abnormalities, a bronchoalveolar lavage may be performed during the bronchoscopy. Saline is introduced into the lungs via the bronchoscope and then recovered for laboratory analysis.
Although the procedure may seem uncomfortable, modern instruments and anaesthesia typically ensure minimal discomfort for the patient.
Lung biopsy (video-assisted thoracoscopic surgery or VATS)
Another method for diagnosing pulmonary fibrosis is a lung biopsy. During the procedure, the surgeon removes small lung tissue samples, which are examined under a microscope by a pathologist. This biopsy helps determine the extent of inflammation and fibrosis, contributing to the final diagnosis.
Diagnosis by a team of specialists
MILO: multidisciplinary interstitial lung disease consultation