Bronchiectasis is an irreversible widening (dilation) of portions of the breathing tubes or airways (bronchi) resulting from damage to the airway wall.
Bronchiectasis can result when conditions directly injure the bronchial wall or indirectly lead to injury by interfering with normal airway defenses. Airway defenses include tiny projections (cilia) on the cells that line the airways. These cilia beat back and forth, moving the thin liquid layer of mucus that normally coats the airways. Harmful particles and bacteria trapped in this mucus layer are moved up to the throat and coughed out or swallowed.
Whether airway injury is direct or indirect, areas of the bronchial wall are damaged and become chronically inflamed. The inflamed bronchial wall becomes less elastic, resulting in the affected airways becoming widened (dilated) and developing small outpouchings or sacs that resemble tiny balloons. Inflammation also increases secretions (mucus). Because cells with cilia are damaged or destroyed, these secretions accumulate in the widened airways and serve as a breeding ground for bacteria. The bacteria further damage the bronchial wall, leading to a vicious circle of infection and airway damage.
Bronchiectasis may affect many areas of the lung (diffuse bronchiectasis), or it may appear in only one or two areas (focal bronchiectasis). Typically, bronchiectasis causes widening of medium-sized airways, but often smaller airways become scarred and destroyed.
The inflammation and infection can extend to the small air sacs of the lungs (alveoli) and cause pneumonia, scarring, and a loss of functioning lung tissue. Severe scarring and loss of lung tissue can ultimately strain the right side of the heart as the heart tries to pump blood through the altered lung tissue. The right-sided heart strain can lead to a form of heart failure called cor pulmonale (see see Sidebar 1: Cor Pulmonale: A Type of Heart Failure Caused by Lung Disorders).
Very severe cases of bronchiectasis, which occur more commonly in underdeveloped countries and in people who have advanced cystic fibrosis, may impair breathing enough to cause abnormally low levels of oxygen and high levels of carbon dioxide in the blood, a condition called respiratory failure (see Respiratory Failure).
The most common cause is severe or repeated respiratory infections. Other causes include
Occasionally, a condition that affects larger airways, called allergic bronchopulmonary aspergillosis, occurs in people with asthma. Allergic bronchopulmonary aspergillosis (see Allergic Bronchopulmonary Aspergillosis) is an allergic reaction to the Aspergillus species, which is a fungal organism. It can cause mucus plugs that obstruct the airways and lead to bronchiectasis.
In many people with bronchiectasis, a cause cannot be determined despite a thorough evaluation.
In developing nations, severe or repeated infections that cause bronchiectasis are more often caused by tuberculosis. Poor nutrition and unavailability of vaccines can also contribute.
Bronchiectasis can develop at any age, but the process often begins in early childhood. However, symptoms may not appear until much later. In most people, symptoms begin gradually, usually after a respiratory infection, and tend to worsen over the years. Most people develop a chronic cough that produces thick sputum. The amount and type of sputum depend on the extent of the disease and whether there is a complicating infection (often called a disease flare). Often, people have coughing spells only early in the morning and late in the day. Coughing up of blood (hemoptysis) is common because the damaged airway walls are fragile and have increased numbers of blood vessels. Hemoptysis may be the first or only symptom.
Recurrent fever or chest pain, with or without frequent bouts of pneumonia, may also occur. People with widespread bronchiectasis may develop wheezing or shortness of breath. People whose bronchiectasis progresses to cor pulmonale or respiratory failure also have fatigue, lethargy, and worsening shortness of breath, particularly during exertion. If bronchiectasis is severe and chronic, people commonly lose lean body mass.
Doctors may suspect bronchiectasis because of a person's symptoms or the presence (currently or in the past) of a condition thought to cause bronchiectasis. Tests are done to confirm the diagnosis and assess the extent and location of the disease. Chest x-rays can often detect the lung changes caused by bronchiectasis. However, occasionally, x-ray results are normal. Computed tomography (CT) is the most accurate test to identify and confirm the diagnosis and to determine the extent and severity of the disease.
Tests are also done to assess how well the lungs are working (pulmonary function tests). These tests measure how well the lungs are able to hold air, to move air in and out, and to exchange oxygen and carbon dioxide. These tests do not diagnose bronchiectasis but do help determine how severe the lung disorder is and are useful for monitoring its progression over time.
After bronchiectasis is diagnosed, tests are often done to check for disorders that may be causing or contributing to it. Such tests may include the following:
When bronchiectasis is limited to one area—for example, a lung lobe or segment—doctors may do a bronchoscopy (see see Bronchoscopy) to determine whether an inhaled foreign object or lung tumor is the cause.
Genetic testing for cystic fibrosis may be needed when there is a family history, repeated respiratory infections, or other unusual findings in a child or adult, even when other typical features of cystic fibrosis are absent.
Doctors may take a sample of sputum and send it to a laboratory to grow (culture) the bacteria to determine which bacteria are present and what antibiotics are most effective against these bacteria.. This testing can help determine the best antibiotics to use during flares.
Early identification and treatment of conditions that tend to cause bronchiectasis may prevent its development or reduce its severity. More than half the cases of bronchiectasis in children can be accurately diagnosed and promptly treated.
Childhood immunizations against measles and whooping cough, improved living conditions, and good nutrition have markedly reduced the number of people who develop bronchiectasis. Annual influenza vaccines, pneumococcal vaccine, and use of appropriate antibiotics early in the course of lung infections help to prevent bronchiectasis or reduce its severity. Receiving immunoglobulin for an immunoglobulin deficiency syndrome may prevent recurring infections. In people who have allergic bronchopulmonary aspergillosis, the appropriate use of corticosteroids and sometimes an antifungal drug (such as itraconazole) may reduce the bronchial damage that results in bronchiectasis. People with alpha1-antitrypsin deficiency may be given the deficient enzyme to help prevent the disorder from becoming more severe.
Avoiding toxic fumes, gases, smoke, and injurious dusts also helps prevent bronchiectasis or reduce its severity. Inhalation of foreign objects into the airways by children may be prevented by watching what they put in their mouth. Avoiding over-sedation due to drugs or alcohol and seeking medical care for neurologic symptoms (such as impaired consciousness) or gastrointestinal symptoms (such as difficulty in swallowing and regurgitation or coughing after eating) may help to prevent aspiration. Also, drops of mineral oil or petroleum jelly should never be placed in the nose because they can be inhaled into the lungs.
Treatment and Prognosis
Treatment of bronchiectasis is directed toward eradicating infections when possible, preventing certain infections with vaccines, decreasing the build-up of mucus, decreasing inflammation, and relieving airway obstruction. Drugs that suppress coughing may worsen the condition and generally should not be used. Early, effective treatment can reduce complications such as hemoptysis, low oxygen levels in the blood, respiratory failure, and cor pulmonale.
Flares are treated with antibiotics, bronchodilators, and chest physical therapy (see Chest Physical Therapy), all of which promote drainage of secretions and mucus, such as postural drainage and chest percussion (see see Postural drainage). Sometimes antibiotics are given for a long period to prevent recurring infections, especially in people who have frequent flares or cystic fibrosis.
For inflammation and the build-up of mucus, humidification of the air and inhaling a salt water solution may help. Drugs that thin the thick sputum (mucolytics) may also be given to people who have cystic fibrosis. In other people, the effectiveness of mucolytics is uncertain.
To detect and treat a bronchial obstruction, bronchoscopy can be used before severe damage occurs (see see Bronchoscopy). Rarely, part of a lung needs to be surgically removed. Such surgery usually is an option only if the disease is confined to one lung or, preferably, to one lung lobe or segment. Surgery may be considered for people who have recurrent infections despite treatment or who cough up large amounts of blood. Occasionally, doctors use a technique called embolization instead of surgery to stop bleeding in people who have a significant amount of bleeding when they cough. Doctors use a catheter to inject a substance that blocks the vessel that is bleeding. If people have low blood oxygen levels, doctors give oxygen therapy (see Oxygen Therapy). Appropriate use of oxygen may help prevent complications such as cor pulmonale. If people have wheezing or shortness of breath, bronchodilators and sometimes inhaled corticosteroids, often help. If a person has a flare, usually these drugs and an antibiotic are given, and oral corticosteroids are added in severe cases. Respiratory failure, if present, should be treated (see see Respiratory Failure).
Lung transplantation can be done in some people who have advanced bronchiectasis, mostly those who also have advanced cystic fibrosis. Five-year survival rates as high as 65 to 75% have been reported when a heart-lung or a double lung transplantation is used. Pulmonary function (as measured by the amount of air in the lungs and the rate and amount of air moving in and out of the lungs with each breath) usually improves within 6 months, and the improvement may be sustained for at least 5 years.
Prognosis for people with bronchiectasis depends on its cause and on how well infections and other complications are prevented or controlled. People with co-existing conditions, such as chronic bronchitis or emphysema, and people who have complications, such as pulmonary hypertension or cor pulmonale, tend to have a worse prognosis.
Last full review/revision August 2013 by Başak Çoruh, MD; Alexander S. Niven, MD; Brian Pomerantz, MD