In pulmonary fibrosis, lung tissue is increasingly being replaced by scar tissue, progressively worsening lung function. Pulmonary fibrosis is therefore primarily characterized by symptoms such as shortness of breath and irritable cough. Fibrosis of the lungs can be caused by various diseases, infections or other harmful influences. Often, however, no cause can be determined - one then speaks of idiopathic pulmonary fibrosis. Course, therapy and life expectancy are dependent on the form of pulmonary fibrosis and therefore individually different for each patient.
What is pulmonary fibrosis?
Pulmonary fibrosis refers to a process in the lungs in which there is a pathological proliferation of scarred connective tissue in the interstitial spaces. As a result, the functional tissue - the alveoli - gradually displaced and the lung function deteriorates increasingly.
Cause are chronic inflammatory processes in the lung, which can be triggered by various factors.
Pulmonary fibrosis: Symptoms include dry cough and shortness of breath
An incipient pulmonary fibrosis first becomes noticeable due to shortness of breath during exercise - later, respiratory distress usually occurs at rest. In addition, patients often complain of dry irritated cough. If necessary - such as when an infection is the cause - fever may occur.
In addition, changes in the hands can usually be found in the advanced stage: Due to the chronic lack of oxygen, there may be a buckling of the nails (watch glass nails) as well as a broadening of the fingertips (drum beater fingers). Also a blue coloring of the skin can occur (cyanosis).
Classification of fibrosis by cause
There are two main groups of pulmonary fibrosis: secondary and idiopathic pulmonary fibrosis. Secondary pulmonary fibrosis is referred to when a cause of the fibrotic lung alteration can be identified.
As a trigger for such secondary pulmonary fibrosis, for example, the following diseases and factors in question:
- Infections, for example, with viruses, the fungus Pneumocystis jirovecii or Legionella
- Autoimmune diseases such as sarcoidosis
- Connective tissue disorders (collagenosis) such as scleroderma, systemic lupus erythematosus or Sjögren syndrome
- Rheumatic diseases such as chronic polyarthritis or vascular inflammation (vasculitis)
- Pulmonary diseases caused by inhaled dust - such as asbestos, fumed silica or metals (pneumoconiosis) or fine dust (exogenous allergic alveolitis)
- inhaled pollutants such as gases, vapors or tobacco smoke
- certain medications (eg chemotherapeutic agents)
- ionizing radiation, for example after radiotherapy
- Diseases that cause chronic pulmonary edema (pulmonary edema), such as heart failure or kidney failure
- certain forms of lung cancer (bronchioloalveolar carcinoma)
In about 50 percent of cases, however, no cause for pulmonary fibrosis can be found. It is then called "idiopathic interstitial pneumonia" (IIP), which means "pneumonia of interstitial cells of unknown cause".
Risk factors for idiopathic pulmonary fibrosis
Within the group of idiopathic pulmonary fibrosis there are again different subforms. The most common of these is idiopathic pulmonary fibrosis (IPF).
Although by definition idiopathic pulmonary fibrosis has no cause, studies suggest that there are some potential risk factors. Influences that may increase the risk for the disease include:
- Environmental pollution such as metal dust, plant dust and livestock dust
- Infections, such as the Epstein-Barr virus or hepatitis C virus
- frequent heartburn (reflux disease)
- Diabetes mellitus
- genetic factors
Diagnostics: Find possible causes
In order to diagnose secondary or idiopathic pulmonary fibrosis, the physician must first ask the patient in detail about possible risk factors, pre-existing conditions, occupation, and other factors. After a physical examination, a pulmonary function test is usually performed.
A blood test can estimate the severity of the lung damage via the oxygen content in the blood. In addition, certain values or markers in the blood can provide indications of possible causes of pulmonary fibrosis.
CT as key diagnostics
An important role in diagnostics is played by computed tomography (CT). As a rule, if lung fibrosis is suspected, high-resolution CT (HR-CT) is performed - it offers a higher resolution than conventional CT and can therefore show the changes in the lung particularly well.
A typical pattern for idiopathic pulmonary fibrosis is called "Usual Interstitial Pneumnonia (UIP)". If this can be determined with certainty, the diagnosis IPF is secured. In all other cases it may be necessary to take a tissue sample of the lung (biopsy). Also a so-called bronchoalveolar lavage, which is carried out by means of lung reflection, may be useful under certain circumstances.
Idiopathic pulmonary fibrosis: drugs are not very promising
In the treatment of secondary pulmonary fibrosis, the treatment of the cause or the avoidance of triggering factors is in the foreground. The treatment of idiopathic pulmonary fibrosis, however, is currently the subject of research: Numerous studies have tested the effectiveness of various drugs, but so far no really promising drug therapy was found (as of October 2016).
In some circumstances, treatment with drugs that suppress the immune system (immunosuppressants) - possibly in combination with cortisone-like active ingredients (corticosteroids) - may lead to an improvement. Recent studies suggest that the drug pirfenidone may slow the progression of pulmonary fibrosis.
Pulmonary rehabilitation as a therapy option
Due to the lack of effective drug therapy options, idiopathic pulmonary fibrosis has a high priority for non-drug treatment. There are special rehabilitation programs for this purpose (so-called pulmonary rehabilitation) which, in addition to training, psychological support and nutritional advice, also include moderate strength and endurance training.
Oxygen therapy can relieve discomfort
As lung function deteriorates, the administration of oxygen can relieve discomfort and improve performance. Such oxygen therapy is also possible at home and on the move using nasal cannulae and a mobile oxygen cylinder.
In addition, all patients with pulmonary fibrosis should stop smoking and receive vaccines against influenza and pneumococci to prevent infection.
Lung Transplantation: Last option in the final stage
A cure of pulmonary fibrosis is not possible, because the scarring of the lung can not be undone. The aim of treatment is therefore to slow down the progression of the disease and to improve the quality of life.
Therefore, lung transplantation may be considered in idiopathic end-stage lung fibrosis. However, many patients are not suitable for transplantation because of comorbidities or too old age.
Life expectancy: how long do patients with pulmonary fibrosis live?
Idiopathic pulmonary fibrosis is usually progressive, whereas the secondary form may be arrested if the cause is successfully treated.
The course and prognosis of the disease are therefore individually different for each patient and a general statement regarding the life expectancy is not possible.
However, the average survival time from the diagnosis of pulmonary fibrosis is given as two to five years.
Pulmonary fibrosis and COPD
To be distinguished from pulmonary fibrosis are the so-called obstructive pulmonary diseases, in which the lung function is not diminished by a scarring, but a constriction or obstruction of the respiratory tract - for instance by mucus.
The best known form is chronic obstructive pulmonary disease (COPD). Also, the hereditary disease cystic fibrosis (misleadingly referred to as cystic fibrosis) is an obstructive disease, as the airways are blocked by viscous mucus.
On the other hand, pulmonary fibrosis is referred to as a restrictive lung disease, as it can no longer develop properly as a result of the scarring and, so to speak, shrinks. However, COPD patients often have pulmonary fibrosis - possibly due to the common risk factor of tobacco smoke.