bronchiectasis bronchiectasis bronchiectasis is a disease in which there is permanent enlargement of parts of the airways of the lung. symptoms typically include a chronic cough with mucus production. other symptoms include shortness of breath, coughing up blood, and chest pain. wheezing and nail clubbing may also occur. those with the disease often get lung infections. bronchiectasisfigure a shows a cross-section of the lungs with normal airways and widened airways. figure b shows a cross-section of a normal airway. figure c shows a cross-section of an airway with bronchiectasis.pronunciation/ˌbrɒŋkɪˈɛktəsɪs/ specialtypulmonologysymptomsproductive cough, shortness of breath, chest painusual onsetgradualdurationlong termcausesinfections, cystic fibrosis, other genetic conditions, unknowndiagnostic methodbased on symptoms, ct scandifferential diagnosischronic obstructive pulmonary disease, asbestosis, tracheobronchomalaciatreatmentantibiotics, bronchodilators, lung transplantfrequency1–250 per 250,000 adults bronchiectasis may result from a number of infectious and acquired causes, including measles, pneumonia, tuberculosis, immune system problems, as well as the genetic disorder cystic fibrosis. cystic fibrosis eventually results in severe bronchiectasis in nearly all cases. the cause in 10–50% of those without cystic fibrosis is unknown. the mechanism of disease is breakdown of the airways due to an excessive inflammatory response. involved airways (bronchi) become enlarged and thus less able to clear secretions. these secretions increase the amount of bacteria in the lungs, resulting in airway blockage and further breakdown of the airways. it is classified as an obstructive lung disease, along with chronic obstructive pulmonary disease and asthma. the diagnosis is suspected based on symptoms and confirmed using computed tomography. cultures of the mucus produced may be useful to determine treatment in those who have acute worsening and at least once a year. periods of worsening may occur due to infection. in these cases, antibiotics are recommended. common antibiotics used include amoxicillin, erythromycin, or doxycycline. antibiotics, such as erythromycin, may also be used to prevent worsening of disease. airway clearance techniques, a type of physical therapy, are also recommended. medications to dilate the airways and inhaled steroids may be used during sudden worsening, but there are no studies to determine effectiveness. there are also no studies on the use of inhaled steroids in children. surgery, while commonly done, has not been well studied. lung transplantation may be an option in those with very severe disease. the disease affects between 1 per 1000 and 1 per 250,000 adults. the disease is more common in women and increases as people age. it became less common since the 1950s with the introduction of antibiotics. it is more common among certain ethnic groups (such as indigenous people in the us). it was first described by rené laennec in 1819. the economic costs in the united states are estimated at $630 million per year. signs and symptoms the typical symptoms of bronchiectasis are shown. also, the change in bronchi under bronchiectasis are illustrated. symptoms of bronchiectasis commonly include a cough productive of frequent green or yellow sputum lasting months to years. other common symptoms include difficulty breathing, wheezing (a whistling sound when you breathe), and chest pain. exacerbations of symptoms may occur, these exacerbations occur more frequently in advanced or severe disease. systemic symptoms, including fevers, chills, night sweats, fatigue and weight loss may be seen with bronchiectasis. bronchiectasis may also present with coughing up blood in the absence of sputum, which has been called "dry bronchiectasis." exacerbations in bronchiectasis present as a worsening of cough, increasing sputum volume or thickened consistency lasting at least 48 hours, worsening shortness of breath (breathlessness), worsening exercise intolerance, increased fatigue or malaise and the development of hemoptysis. people often report frequent bouts of "bronchitis" requiring therapy with repeated courses of antibiotics. people with bronchiectasis may have bad breath from active infection. on examination, crepitations and expiratory rhonchi may be heard with auscultation. nail clubbing is a rare symptom. the complications of bronchiectasis include serious health conditions, such as respiratory failure and atelectasis: collapse or closure of a lung. respiratory failure occurs when not enough oxygen passes from the lungs into the blood. atelectasis occur when one or more segments of the lungs collapse or do not inflate properly. other pulmonary complications include lung abscess and empyema. cardiovascular complications include cor pulmonale, in which there is enlargement and failure of the right side of the heart as a result of disease of the lungs. causes category causes autoimmune disease rheumatoid arthritis sjögren syndrome impaired host defenses cystic fibrosis primary ciliary dyskinesia primary immunodeficiency hiv/aids job's syndrome post-infective bacterial pneumonia mycobacterium infection viral infection congenital tracheobronchomegaly marfan syndrome williams–campbell syndrome young's syndrome alpha-1 antitrypsin deficiency hypersensitivity allergic bronchopulmonary aspergillosis inflammatory bowel disease ulcerative colitis crohn's disease malignancy chronic lymphocytic leukemia graft-versus-host disease obstruction tumor foreign body aspiration lymphadenopathy other pneumonia chronic aspiration ammonia inhalation smoke inhalation radiation-induced lung disease yellow nail syndrome there are many causes that can induce or contribute to the development of bronchiectasis. the frequency of these different causes varies with geographic location. cystic fibrosis is identified as a cause in up to half of cases. bronchiectasis without cf is known as non-cf bronchiectasis. historically, about half of all case of non-cf bronchiectasis were found to be idiopathic, or without a known cause. however, more recent studies with a more thorough diagnostic work-up have found an etiology in 60 to 90% of patients. cystic fibrosis cystic fibrosis is the most common life-threatening autosomal recessive disease in the united states and europe. it is a genetic disorder that affects the lungs, but also the pancreas, liver, kidneys, and intestine. it is caused by mutations in the cftr protein, a chloride channel expressed in epithelial cells. lung disease results from clogging of the airways due to mucus build-up, decreased mucociliary clearance, and resulting inflammation. in later stages, changes to the structure of the lung, such as bronchiectasis, occur. around 5 to 10% of all patients with cystic fibrosis develop bronchiectasis. airway obstruction an airway obstruction can be caused by either an intraluminal mass such as a tumor or a foreign body. the presence of an airway obstruction leads to a cycle of inflammation. it is important to identify the presence of an obstruction because surgical resection is often curative if obstruction is the cause. in adults, foreign body aspiration is often associated with an altered state of consciousness. the foreign body is often unchewed food, or part of a tooth or crown. bronchiectasis that results from foreign body aspiration generally occurs in the right lung in the lower lobe or posterior segments of the upper lobe. lung infections a range of bacterial, mycobacterial, and viral lung infections are associated with the development of bronchiectasis. bacterial infections commonly associated with bronchiectasis include p. aeruginosa, h. influenzae, and s. pneumoniae. gram-negative bacteria are more commonly implicated than gram-positive bacteria. a history of mycobacterial infections such as tuberculosis can lead to damage of the airways that predisposes to bacterial colonization. severe viral infections in childhood can also lead to bronchiectasis through a similar mechanism. nontuberculous mycobacteria infections such as mycobacterium avium complex are found to be a cause in some patients. recent studies have also shown nocardia infections to been implicated in bronchiectasis. impaired host defenses impairments in host defenses that lead to bronchiectasis may be congenital, such as with primary ciliary dyskinesia, or acquired, such as with the prolonged use of immunosuppressive drugs. additionally, these impairments may be localized to the lungs, or systemic throughout the body. in these states of immunodeficiency, there is a weakened or absent immune system response to severe infections that repeatedly affect the lung and eventually result in bronchial wall injury. hiv/aids is an example of an acquired immunodeficiency that can lead to the development of bronchiectasis. aspergillosis allergic bronchopulmonary aspergillosis (abpa) is an inflammatory disease caused by hypersensitivity to the fungus aspergillus fumigatus. it is suspected in patients with a long history of asthma and symptoms of bronchiectasis such as a productive, mucopurulent cough. imaging often shows peripheral and central airway bronchiectasis, which is unusual in patients with bronchiectasis caused by other disorders. autoimmune diseases several autoimmune diseases have been associated with bronchiectasis. specifically, individuals with rheumatoid arthritis and sjögren syndrome have increased rates of bronchiectasis. in these diseases, the symptoms of bronchiectasis usually presents later in the disease course. other autoimmune diseases such as ulcerative colitis and crohn's disease also have an association with bronchiectasis. additionally, graft-versus-host disease in patients who have undergone stem cell transplantation can lead to bronchiectasis as well. lung injury bronchiectasis could be caused by: inhalation of ammonia and other toxic gases, chronic pulmonary aspiration of stomach acid from esophageal reflux, or a hiatal hernia. congenital bronchiectasis may result from congenital disorders that affect cilia motility or ion transport. a common genetic cause is cystic fibrosis, which affects chloride ion transport. another genetic cause is primary ciliary dyskinesia, a rare disorder that leads to immotility of cilia and can lead to situs inversus. when situs inversus is accompanied by chronic sinusitis and bronchiectasis, this is known as kartagener's syndrome. other rare genetic causes include young's syndrome and williams-campbell syndrome. tracheobronchomegaly, or mournier-kuhn syndrome is a rare condition characterized by significant tracheobronchial dilation and recurrent lower respiratory tract infections. individuals with alpha 1-antitrypsin deficiency have been found to be particularly susceptible to bronchiectasis, due to the loss of inhibition to enzyme elastase which cleaves elastin. this decreases the ability of the alveoli to return to normal shape during expiration. cigarette smoking a causal role for tobacco smoke in bronchiectasis has not been demonstrated. nonetheless, tobacco smoking can worsen pulmonary function and accelerate the progression of disease that is already present. pathophysiology "vicious cycle" theory of the pathogenesis of bronchiectasis. the development of bronchiectasis requires two factors: an initial injury to the lung (such as from infection, auto-immune destruction of lung tissue, or other destruction of lung tissue (as seen in gastroesophageal reflux disease or aspiration syndromes)) which leads to impaired mucociliary clearance, obstruction, or a defect in host defense. this triggers a host immune response from neutrophils (elastases), reactive oxygen species, and inflammatory cytokines that results in progressive destruction of normal lung architecture. in particular, the elastic fibers of bronchi are affected. the result is permanent abnormal dilation and destruction of the major bronchi and bronchiole walls. disordered neutrophil function is believed to play a role in the pathogenesis of bronchiectasis. neutrophil extracellular traps (nets), which are extracellular fibers secreted by neutrophils that are used to trap and destroy pathogens, are hyperactive in bronchiectasis. increased net activity is associated with more severe bronchiectasis. neutrophil elastase, which is an extracellular protein secreted by neutrophils to destroy pathogens as well as host tissue, is also hyperactive in many cases of bronchiectasis. an increased neutrophil elastase activity is also associated with worse outcomes and more severe disease in bronchiectasis. the initial lung injury in bronchiectasis leads to an impaired mucociliary clearance of the lung airways, which leads to mucous stasis. this mucous stasis leads to bacterial colonization in bronchiectasis which leads to neutrophil activation. this neutrophil activation leads to further tissue destruction and airway distortion by neutrophils in addition to direct tissue destruction by the pathogenic bacteria. the distorted, damaged lung airways thus have impaired mucociliary clearance; leading to mucous stasis and bacterial colonization leading to further neutrophil activation and thus fueling a self-perpetuating "vicious cycle" of inflammation in bronchiectasis. this "vicious cycle" theory is the generally accepted explanation for the pathogenesis of bronchiectasis. endobronchial tuberculosis commonly leads to bronchiectasis, either from bronchial stenosis or secondary traction from fibrosis. traction bronchiectasis characteristically affects peripheral bronchi (which lack cartilage support) in areas of end-stage fibrosis. diagnosis ct scan of the lungs showing findings diagnostic of bronchiectasis. white and black arrows point to dilated bronchi characteristic of the disease. the goals of a diagnostic evaluation for bronchiectasis are radiographic confirmation of the diagnosis, identification of potential treatable causes, and functional assessment of the patient. a comprehensive evaluation consists of radiographic imaging, laboratory testing, and lung function testing. laboratory tests that are commonly part of the initial evaluation include a complete blood count, sputum cultures for bacteria, mycobacteria, and fungi, testing for cystic fibrosis, and immunoglobulin levels. additional tests that are sometimes indicated include testing for specific genetic disorders. lung function testing is used for the assessment and monitoring of functional impairment due to bronchiectasis. these tests may include spirometry and walking tests. obstructive lung impairment is the most common finding