| Bronchiectasis | |
|---|---|
| Classification and external resources | |
| ICD-10 | J47, Q33.4 |
| ICD-9 | 494, 748.61 |
| DiseasesDB | 1684 |
| MedlinePlus | 000144 |
| eMedicine | med/246 |
| MeSH | D001987 |
Bronchiectasis is a disease state defined by localized, irreversible dilation of part of the bronchial tree caused by destruction of the muscle and elastic tissue. It is classified as an obstructive lung disease, along with emphysema, bronchitis, asthma, and cystic fibrosis. Involved bronchi are dilated, inflamed, and easily collapsible, resulting in airflow obstruction and impaired clearance of secretions. Bronchiectasis is associated with a wide range of disorders, but it usually results from bacterial infections, such as infections caused by the Staphylococcus or Klebsiella species or Bordetella pertussis.[1]
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People with bronchiectasis produce frequent green/yellow sputum (patients with bronchiectasis may produce 240ml (8 oz) of sputum daily). They may have bad breath and, when associated with cystic fibrosis, diarrhea (patients with cystic fibrosis often develop chronic pancreatitis).
The diagnosis of bronchiectasis is based on the review of clinical history and characteristic patterns in high-resolution CT scan findings. Such patterns include "tree-in-bud" abnormalities and cysts with definable borders. In one small study, CT findings of bronchiectasis and multiple small nodules were reported to have a sensitivity of 80%, specificity of 87%, and accuracy of 80% for the detection of bronchiectasis. Bronchiectasis may also be diagnosed without CT scan confirmation if clinical history clearly demonstrates frequent respiratory infections as well as confirmation of an underlying problem via blood work and sputum culture samples.[2]
Bronchiectasis has both congenital and acquired causes, with the latter more frequent.
Acquired Immune Deficiency Syndrome (AIDS) is the leading cause of bronchiectasis, especially in children. AIDS predisposes patients to a variety of pulmonary ailments, such as pneumonia and other opportunistic infections.[3]
Tuberculosis is another major cause. Endobronchial tuberculosis commonly leads to bronchiectasis, either from bronchial stenosis or secondary traction from fibrosis.[4]
Bronchiectasis can sometimes be an unusual complication of inflammatory bowel disease, especially ulcerative colitis. It can occur in Crohn's disease as well, but does so less frequently. Bronchiectasis in this situation usually stems from various allergic responses to inhaled fungus spores.[5]
Recent evidence has shown an increased risk of bronchiectasis in patients with rheumatoid arthritis who smoke. One study stated a tenfold increased prevalence of the disease in this cohort.[6] Still, it is unclear as to whether or not cigarette smoke is a specific primary cause of bronchiectasis.
Other acquired causes of bronchiectasis involving environmental exposures include respiratory infections, obstructions, inhalation and aspiration of ammonia and other toxic gases, pulmonary aspiration, alcoholism, heroin (drug use), various allergies,[7] and allergic bronchopulmonary aspergillosis.[8]
Kartagener syndrome, which affects the mobility of cilia in the lungs,[9] aids in the development of the disease. Another common genetic cause is cystic fibrosis, in which a small number of patients develop severe localized bronchiectasis.[10] Young's syndrome, which is clinically similar to cystic fibrosis, is thought to significantly contribute to the development of bronchiectasis. This is due to the occurrence of chronic, sinopulmonary infections.[11] Patients with alpha 1-antitrypsin deficiency have been found to be particularly susceptible to bronchiectasis, for unknown reasons.[12] Other less-common congenital causes include primary immunodeficiencies, due to the weakened or nonexistent immune system response to severe, recurrent infections that commonly affect the lung.[13] Several other congenital disorders can also lead to bronchiectasis, including Williams-Campbell syndrome and Marfan syndrome.[14]
In order to prevent bronchiectasis, children should be immunized against measles, pertussis and other acute respiratory infections of childhood. While smoking has not been found to be a direct cause of bronchiectasis, it is certainly an irritant that all patients should avoid in order to prevent the development of infections (such as bronchitis) and further complications.[15]
A healthy body mass index, vaccination (especially against pneumonia and influenza) and regular doctor visits may have beneficial effects on the prevention of progressing bronchiectasis. The presence of hypoxemia, hypercapnia, dyspnea level and radiographic extent can greatly affect the mortality rate from this disease.[16]
Treatment of bronchiectasis includes controlling infections and bronchial secretions, relieving airway obstructions, removal of affected portions of lung by surgical removal or artery embolization and preventing complications. This includes the prolonged usage of antibiotics to prevent detrimental infections,[17] as well as eliminating accumulated fluid with postural drainage and chest physiotherapy. Surgery may also be used to treat localized bronchiectasis, removing obstructions that could cause progression of the disease.[18]
Inhaled steroid therapy that is consistently adhered to can reduce sputum production and decrease airway constriction over a period of time, and help prevent progression of bronchiectasis. One commonly used therapy is beclometasone dipropionate, which is also used in asthma treatment.[19] Use of inhalers such as albuterol (salbutamol), fluticasone (Flovent/Flixotide) and ipratropium (Atrovent) may help reduce likelihood of infection by clearing the airways and decreasing inflammation.[20]
Although not approved for use in any country, Mannitol dry inhalation powder, under the name Bronchitol, has been granted orphan drug status by the FDA for use in patients with bronchiectasis and with cystic fibrosis.[21]
Combination therapies, long acting bronchodilators and inhaled corticosteroids such as Symbicort and Advair Diskus are also commonly used inhaled medicines which has in many cases been effective in clearing the airways, reducing sputum and reducing inflammation.
Rene Laënnec, the man who invented the stethoscope, used his invention to first discover bronchiectasis in 1819.[22] The disease was researched in greater detail by Sir William Osler in the late 1800s; it is suspected that Osler actually died of complications from undiagnosed bronchiectasis.[23]
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