Bronchiolitis obliterans is a chronic disease of the bronchioles. It is progressive and eventually leads to obstruction of the bronchioles. At times, lung transplantation must be performed in the final stages of the disease.
What is bronchiolitis obliterans?
Bronchiolitis obliterans is characterized by inflammatory processes in the bronchioles that do not resolve. The bronchioles represent the small branches of the bronchial tree and are already adjacent to the alveoli of the lung. They now have only a single-layered ciliated epithelium and no goblet cells. Their opening is ensured only by elastic fibers. Furthermore, they divide further into four to five terminal bronchioles, which in turn divide into the bronchioli respiratorii, which are about 1 to 1.35 millimeters long and 0.4 millimeters wide. Sometimes their wall is already formed by alveoli (pulmonary alveoli). Thus, the bronchioles open into the alveoli. The chronic inflammatory processes in the bronchioles naturally also constantly stress the lung tissue. In the course of the inflammations, scarring occurs, which leads to obstructions (occlusions). The scarring does occur to contain the inflammation. However, because of this, the disease progresses steadily and in the final stage forms a complete occlusion of the bronchioles. Gas exchange is then no longer possible.
Causes
The causes of bronchiolitis obliterans are varied. For example, previous infections, autoimmune diseases, or applications of medications can lead to the chronic inflammation. Patients with rheumatic diseases may also develop chronic bronchiolitis. Bronchiolitis obliterans also often develops as a result of chronic rejection following lung transplantation. In addition, it was also reported in the Washington Morning Post that especially workers who work in the factories for the production of microwave popcorn often suffer from this disease. Diacetyl, which is found in butter flavoring, was blamed as the cause here. Possibly, allergic reactions against this compound initiate the inflammatory processes in the bronchioles. In any case, the term popcorn workers’ lung has already been coined for this phenomenon. As part of the inflammatory processes, a fibrin-rich exudate forms, which obstructs the bronchioles and the outer alveoli. In the long term, the bronchioles are closed by scarring remodeling processes with the formation of connective tissue, thus impeding gas exchange. The exact cause of these inflammatory processes is not known. However, cytokines are thought to play a significant role in the pathogenesis of the disease. The exudate produced in the alveoli during inflammation prompts the formation of granulation tissue in the bronchioles. However, with this temporarily formed tissue, the openings of the bronchioles are gradually narrowed. In the advanced stage, the inflammation spreads to the adjacent lung parenchyma. This stage is called bronchiolitis obliterans with organizing pneumonia (BOOP).
Symptoms, complaints, and signs
Bronchiolitis obliterans is characterized by pathologic secondary sounds (stridor) during breathing. The sounds occur especially during exhalation. In addition, the disease is characterized by increasing dyspnea. The patient is also plagued by a constant and agonizing cough. In the long term, the breathing difficulties lead to an undersaturation of the blood with oxygen, which manifests itself as cyanosis in the form of bluish discolored lips. The thorax is hyperinflated. This is followed by states of exhaustion and often confusion as a result of insufficient oxygen supply to the brain. The symptoms resemble those of bronchial asthma or COPD. The bronchial lumen becomes coated with viscous mucus due to the constant formation of the fibrin-rich exudate. In the untreated end stage, life can only be saved by lung transplantation.
Diagnosis and course
To diagnose bronchiolitis obliterans, bronchial asthma and COPD must be excluded by differential diagnosis. The symptoms of these conditions are similar. Imaging techniques are not informative in this regard because they only visualize changes that may have multiple causes. Only a lung biopsy can confirm the diagnosis.Bronchiolitis is evident here, although the signs of inflammatory processes in the alveoli are absent. This implies a clear indication of chronic bronchiolitis, which only later spreads to the lung tissue. When bronchiolitis obliterans develops after lung transplantation, radiologic studies without lung biopsy are often sufficient to confirm the diagnosis.
Complications
Bronchial disease can affect the function of the lungs. Therefore, caution as well as adherence to medical diagnosis is required, otherwise complications such as bronchiolitis obliterans may occur. This is especially true for young children, the elderly, and patients who are affected by an infection after a lung transplant. Once the disease has reached the bronchiolar level, if the symptoms are ignored, the patient progressively deteriorates. As a result, healthy lung tissue is rejected or the transplant is unsuccessful. Bronchiolitis obstructs the granulation tissue, flow obstruction occurs, and bulging scars form due to the restricted lung volume. The scarring occurs because the body is trying to counteract previous inflammation that is still in the lungs. The healing process is counterproductive and is the most serious rejection reaction after a lung transplant. Antibiotics can no longer take effect and cortisone therapy for several months must be sought. Patients who are at increased risk of being affected by inflammatory respiratory diseases must be especially wary of viral superinfections. Infants whose fine bronchial branches are pre-damaged can be in serious danger of death from diseases such as measles, influenza viruses or from mycoplasma. Even if the inflammatory symptoms are mild, bronchiectasis, bronchopneumonia, and complications such as obstructive ventilation disorder may occur later in adult life.
When should you see a doctor?
Since bronchiolitis obliterans is a very serious disease, a doctor must be consulted in any case. As a rule, the doctor should be contacted already when there are various side noises and discomfort during breathing. Shortness of breath or gasping for breath can also indicate the disease and should be examined. In this case, most patients also suffer from persistent coughing and also blue discoloration of the skin and lips. A visit to the doctor is also necessary for these symptoms. Furthermore, bronchiolitis obliterans can lead to permanent fatigue or exhaustion. Patients are often confused or suffer from concentration disorders. Therefore, if these complaints occur without any particular reason, a doctor should be consulted to have bronchiolitis obliterans ruled out or confirmed. As a rule, the ENT physician or pulmonologist should be consulted for this disease. He or she can correctly classify and treat the symptoms. However, in severe cases, transplantation of a lung is also necessary, which is performed in a hospital.
Treatment and therapy
Once the diagnosis has been confirmed, rapid action must be taken to prevent progression of the disease. Cortisone therapy for at least six months is suitable for this purpose. If this treatment is not initiated, serious courses are to be feared. In some cases, cyclophosphamide or cyclosporine may also be used. Treatment for bronchiolitis obliterans sometimes ends with lung transplantation. To prevent it from getting to that point, the underlying disease should be sought to be treated. Sometimes it may be enough to eliminate the influence of certain environmental toxins. The phenomenon of “popcorn workers’ lung” has already been reported above. Here, the presumed trigger of the disease is the active ingredient diacetyl found in butter flavoring. Constant inhalation of toxic gases such as NO2 can also lead to irritation of the bronchioles. Preventing exposure to these toxins may already lead to improvement of symptoms.
Outlook and prognosis
Bronchiolitis obliterans usually has a poor prognosis. Among other things, it is itself a complication of lung transplantation, with the immune system turning against the foreign lung tissue.However, autoimmune reactions against the lungs or chronic inflammation as a result of infections or the influence of medication also irreversibly remodel the lung tissue in the long term. The course of the disease cannot be stopped, but drug treatment with immunosuppressants in the form of cortisone can slow down the remodeling processes. As a result of the constant inflammation, fibrin formation occurs, leading to scarring and narrowing of the bronchioles and adjacent alveoli. This process is progressive and irreversible. Increasingly, there are respiratory symptoms that are constantly worsening. There is currently no curative therapy. The course of the disease becomes even more severe when the inflammation spreads to the adjacent lung parenchyma. Bronchiolitis obliterans with organizing pneumonia then develops, which is also known as BOOP. BOOP is characterized by a subacute onset with flu-like symptoms such as fever, fatigue, cough, increasing difficulty breathing, and severe feeling of illness. In individual cases, this course can be very massive and life-threatening. However, the long-term course of the disease also eventually leads to death. Within three years, 50 percent of patients die. Only 30 to 50 percent of those affected are still alive five years after diagnosis. However, intensive drug therapy can greatly delay the course of the disease.
Prevention
The general recommendation for preventing bronchiolitis obliterans is to maintain a healthy lifestyle with plenty of exercise, a balanced diet, and abstinence from smoking. However, because the causes of this disease are many, there is no guarantee that bronchiolitis obliterans will not then develop, despite a healthy lifestyle.
Follow-up
In most cases, no special or direct measures of aftercare are available to the affected person with bronchiolitis obliterans. The affected person is thereby dependent on symptomatic treatment, since causal therapy is usually not possible in this disease. However, the earlier the disease is detected, the better the further course is usually. Bronchiolitis obliterans, however, usually leads to the death of the affected person and thus to a significantly reduced life expectancy. In most cases, bronchiolitis obliterans is treated with the help of medication. The affected person should pay attention to a correct and regular intake. The doctor’s instructions should also be followed, although in cases of doubt or ambiguity the doctor should always be contacted again. In order to avoid unnecessary strain on the body, smoking should also be avoided in bronchiolitis obliterans. Strenuous physical work should also be avoided. In many cases, the disease also leads to physical upsets or depression. These should always be treated by a psychologist, although discussions with one’s own family can also be very helpful.
What you can do yourself
Bronchiolitis obliterans is a see severe disease of the bronchi that often requires a lung transplant even with professional treatment. Therefore, self-treatment of the disease is completely out of the question. Affected persons must consult a physician without fail. However, patients can also contribute to an improvement of the disease themselves. Since bronchiolitis obliterans is associated with chronic inflammatory processes that permanently stress the body, those affected should pay attention to a healthy lifestyle that supports the immune system. A healthy diet, avoidance of excessive alcohol, sufficient sleep and, if the patient is able, light endurance sports in the fresh air are helpful. As with all diseases of the bronchi and lungs, smoking tobacco should be avoided. Simple home remedies can alleviate the strong and usually very agonizing cough that often accompanies bronchiolitis obliterans. In natural medicine, sage-based preparations are used, which are available in the form of tea or lozenges. Gargling with salt water keeps the throat and pharynx moist and has a disinfecting effect. This can prevent the area irritated by constant coughing from becoming additionally inflamed.If the cause of the disease could not be determined, patients should consider whether there are allergenic substances, for example chemicals, in their (work) environment that could be the trigger for the disease and be sure to bring this to the attention of the attending physician.