Bronchiectasis
Bronchiectasis | |
---|---|
Frequency | 1–250 per 250,000 adults[10] |
Bronchiectasis is a disease in which there is permanent enlargement of parts of the
Bronchiectasis may result from a number of
Periods of worsening may occur due to infection.
The disease affects between 1 per 1000 and 1 per 250,000 adults.
Signs and symptoms
Symptoms of bronchiectasis commonly include a cough productive of frequent green or yellow sputum lasting months to years.[3] 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.[21] Systemic symptoms, including fevers, chills, night sweats, fatigue and weight loss may be seen with bronchiectasis.[21] 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.[21]
People often report frequent bouts of "bronchitis" requiring therapy with repeated courses of antibiotics. People with bronchiectasis may have
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.[22] 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.[23]
Causes
Category | Causes |
---|---|
Autoimmune disease | Rheumatoid arthritis |
Impaired host defenses | Cystic fibrosis
Job's syndrome
|
Post-infective | Bacterial pneumonia
Mycobacterium infection Viral infection |
Congenital | Tracheobronchomegaly |
Hypersensitivity | Allergic bronchopulmonary aspergillosis |
Inflammatory bowel disease | Ulcerative colitis |
Malignancy | Chronic lymphocytic leukemia |
Obstruction | Tumor
|
Other | Pneumonia
Chronic aspiration Ammonia inhalation Radiation-induced lung disease |
There are many causes that can induce or contribute to the development of bronchiectasis. The frequency of these different causes varies with geographic location.[24] Cystic fibrosis is identified as a cause in up to half of cases.[3] 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.[25] However, more recent studies with a more thorough diagnostic work-up have found an etiology in 60 to 90% of patients.[24][26][27]
Cystic fibrosis
Airway obstruction
An airway obstruction can be caused by either an
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.[3] Gram-negative bacteria are more commonly implicated than gram-positive bacteria.[3] A history of mycobacterial infections such as tuberculosis can lead to damage of the airways that predisposes to bacterial colonization.[35] Severe viral infections in childhood can also lead to bronchiectasis through a similar mechanism.[36] Nontuberculous mycobacteria infections such as Mycobacterium avium complex are found to be a cause in some patients.[37] Recent studies have also shown Nocardia infections to been implicated in bronchiectasis.[38]
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.[39] 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.[40] HIV/AIDS is an example of an acquired immunodeficiency that can lead to the development of bronchiectasis.[41]
Aspergillosis
Allergic bronchopulmonary aspergillosis (ABPA) is an inflammatory disease caused by hypersensitivity to the fungus Aspergillus fumigatus.[42] It is suspected in patients with a long history of asthma and symptoms of bronchiectasis such as a productive, mucopurulent cough.[43] Imaging often shows peripheral and central airway bronchiectasis, which is unusual in patients with bronchiectasis caused by other disorders.[44]
Autoimmune diseases
Several autoimmune diseases have been associated with bronchiectasis. Specifically, individuals with rheumatoid arthritis and Sjögren syndrome have increased rates of bronchiectasis.[45][46] In these diseases, the symptoms of bronchiectasis usually presents later in the disease course.[47] Other autoimmune diseases such as ulcerative colitis and Crohn's disease also have an association with bronchiectasis.[48] Additionally, graft-versus-host disease in patients who have undergone stem cell transplantation can lead to bronchiectasis as well.[39]
Lung injury
Bronchiectasis could be caused by: inhalation of
Congenital
Bronchiectasis may result from congenital disorders that affect
Cigarette smoking
A causal role for tobacco smoke in bronchiectasis has not been demonstrated.[39] Nonetheless, tobacco smoking can worsen pulmonary function and accelerate the progression of disease that is already present.[59][60]
Pathophysiology
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
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.[21] 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.[21] An increased neutrophil elastase activity is also associated with worse outcomes and more severe disease in bronchiectasis.[21] The initial lung injury in bronchiectasis leads to an impaired mucociliary clearance of the lung airways, which leads to mucous stasis.[21] This mucous stasis leads to bacterial colonization in bronchiectasis which leads to neutrophil activation.[21] This neutrophil activation leads to further tissue destruction and airway distortion by neutrophils in addition to direct tissue destruction by the pathogenic bacteria.[21] 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.[21] This "vicious cycle" theory is the generally accepted explanation for the pathogenesis of bronchiectasis.[39]
Endobronchial tuberculosis commonly leads to bronchiectasis, either from bronchial stenosis or secondary traction from fibrosis.[34] Traction bronchiectasis characteristically affects peripheral bronchi (which lack cartilage support) in areas of end-stage fibrosis.[62]
Diagnosis
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.[63]
Laboratory tests that are commonly part of the initial evaluation include a
Lung function testing is used for the assessment and monitoring of functional impairment due to bronchiectasis. These tests may include spirometry and walking tests.[39] Obstructive lung impairment is the most common finding but restrictive lung impairment can be seen in advanced disease. Flexible bronchoscopy may be performed when sputum studies are negative and a focal obstructing lesion is suspected.[31]
A
-
Bronchiectasis primarily in themiddle lobeof the right lung.
-
Bronchiectasis secondary to a large carcinoid tumor (not shown) that was completely obstructing the bronchus proximally. Dilation of the airways is present.
Prevention
In preventing bronchiectasis, it is necessary to prevent the lung infections and lung damage that can cause it.
Treatments to slow down the progression of this chronic disease include keeping bronchial airways clear and secretions weakened through various forms of
Management
A comprehensive approach to the management of bronchiectasis is recommended.[69] It is important to establish whether an underlying modifiable cause, such as immunoglobulin deficiency or alpha-1 antitrypsin deficiency is present.[69] The next steps include controlling infections and bronchial secretions, relieving airway obstructions, removing affected portions of lung by surgery, and preventing complications.[70]
Airway clearance
The goal of
Anti-inflammatories
The two most commonly used classes of anti-inflammatory therapies are macrolides and corticosteroids.[3]
Despite also being antibiotics, macrolides exert
Antibiotics
Bronchodilators
Some clinical trials have shown a benefit with inhaled bronchodilators in certain people with bronchiectasis.[3] In people with demonstrated bronchodilator reversibility on spirometry, the use of inhaled bronchodilators resulted in improved dyspnea, cough, and quality of life without any increase in adverse events.[63] However, overall there is a lack of data to recommend use of bronchodilators in all patients with bronchiectasis.[80]
Surgery
The primary role of surgery in the management of bronchiectasis is in localized disease to remove segments of the lung or to control massive hemoptysis.[39] Additionally, surgery is used to remove an airway obstruction that is contributing to bronchiectasis. The goals are conservative, aiming to control specific disease manifestations rather than cure or eliminate all areas of bronchiectasis.[81] Surgical case series have shown low operative mortality rate (less than 2%) and improvement of symptoms in the majority of patients selected to receive surgery.[82] However, no randomized clinical trials have been performed evaluating the efficacy of surgery in bronchiectasis.[81]
Clinical trials
Results from a phase 2 clinical trial were published in 2018.[83] In a placebo-controlled, double-blind study conducted in 256 patients worldwide, patients who received Brensocatib reported prolonged time to the first exacerbation and also reduced rate of yearly exacerbation.
Prognosis
Two clinical scales have been used to predict disease severity and outcomes in bronchiectasis; the Bronchiectasis Severity Index and the FACED scale. The FACED scale uses the
Epidemiology
The prevalence and incidence of bronchiectasis is unclear as the symptoms are variable.
An estimated 350,000 to 500,000 adults have bronchiectasis in the United States.[86] Specifically, children of the indigenous populations of Australia, Alaska, Canada and New Zealand have significantly higher rates than other populations.[87] Overall, a shortage of data exists concerning the epidemiology of bronchiectasis in Asia, Africa, and South America.[87]
The prevalence and incidence of bronchiectasis has increased greatly in the 21st century. In a Medicare cohort analysis, consisting of adults 65 years and older in the United States; the annual rates of diagnosis have increased by 8.7% every year between 2000 and 2007.[3][88] This large increase in the diagnosis of bronchiectasis may be due to increased recognition of the disease (including more widespread use of CT scans) or it may be due to an increase in the underlying causes of bronchiectasis.[21]
History
René Laennec, the man who invented the stethoscope, used his invention to first discover bronchiectasis in 1819.[89]
The disease was researched in greater detail by Sir William Osler, one of the four founding professors of Johns Hopkins Hospital, in the late 1800s. It is suspected that Osler himself died of complications from undiagnosed bronchiectasis. His biographies mention that he had frequent severe chest infections for many years.[90]
The term "bronchiectasis" comes from the Greek words bronkhia (meaning "airway") and ektasis (meaning "widening").[91]
Society and culture
Judith Durham of the Australian band The Seekers died of bronchiectasis on August 5, 2022, at the age of 79.[92]
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