Bronchiectasis

NORMAL LUNGS: YOUR LUNGS AS A "TREE"

Your lungs can be likened to a "tree". When you breathe in, air is drawn through the nose and mouth into the windpipe (or trachea). This is the trunk of the tree. From the windpipe, air passes into two large bronchial tubes (bronchi), one supplying air to each lung. These bronchial tubes are the first "branches" of the tree. They divide into smaller and smaller branches, delivering air into tiny air sacs, called alveoli. The alveoli are the "leaves" of the tree. From these alveoli, oxygen is taken from the breathed-in air, and passed into the bloodstream. The oxygen is taken to all the organs of the body, such as the heart and brain.

BRONCHI: THE LUNG'S "CLEARING" MECHANISM

As well as delivering air into the alveoli, the bronchi (branches) also produce a sticky substance called mucus. This traps inhaled bacteria, dusts and other harmful particles, and stops them from entering the lung tissue. Tiny "hairs", called cilia, on the inside wall of the bronchi are beating constantly like grass in the wind, and waft the mucus back up the bronchial tree where it is cleared. These cilia ensure that mucus does not build up in the bronchi. Excess mucus can reduce the flow of air through the bronchi, and also become infected if it is there for a long time.

BRONCHIECTASIS: A DISEASE OF THE BRONCHI ("BRANCHES")

In the condition known as bronchiectasis, the bronchial tubes become wider than usual (or dilated) and the wall of the tube becomes damaged and functions less effectively. The cilia on the wall of the affected tube are destroyed, so that mucus is no longer cleared away and collects in the tube. The collected mucus obstructs the flow of air through the affected bronchi, and also eventually becomes contaminated with bacteria, causing bronchial infection. This infection causes inflammation in the bronchi. This damages the bronchial wall even further, and so we have a vicious circle of damage leading to infection leading to further damage and infection. The inflammation spreads to surrounding bronchi and lung tissue. Bronchiectasis can affect a small area of one lung (focal bronchiectasis) or affect widespread and different areas of the lungs (diffuse bronchiectasis), which is much more common.

DO WE KNOW WHAT CAUSES BRONCHIECTASIS?

In about half of cases, the cause of bronchiectasis is not known. There are, however, some conditions that are knownto cause bronchiectasis. Previous pneumonia, as a child or young adult, can damage that area of the lung where the pneumonia was present. This can lead to bronchiectasis in that area. It is suggested that childhood whooping cough and measles can sometimes result in bronchiectasis. Tuberculosis (TB) can cause bronchiectasis in the affected lung areas. A foreign body trapped in a bronchial tube for a long period, such as an inhaled peanut or other piece of food, can cause bronchiectasis. Viral infections can lower immunity and lead to bronchiectasis. Cystic fibrosis is a common genetic disease in which the mucus in the bronchi is much thicker and stickier than usual, making it very difficult to clear. In addition, the cilia do not function normally. This leads to diffuse bronchiectasis throughout the lungs. Cystic fibrosis is the commonest cause of bronchiectasis in children and young adults, and the cause is usually obvious. However, some people with milder forms of cystic fibrosis may have no problems in early life, but present with bronchiectasis in their 30's or middle age. Abnormally low levels of important certain blood proteins, such as immunoglobulins or alpha-1 antitrypsin can lead to diffuse bronchiectasis. These proteins protect the lungs against infection. If their levels are too low, then the lung can become damaged. The low levels are usually caused by a genetic deficiency. Other causes include a rare genetic disease called primary ciliary dyskinesia, which results in abnormal cilia that do not function properly. Acid reflux from the stomach can sometimes spill over into the bronchial tubes and cause bronchiectasis. Disease such as ulcerative colitis and rheumatoid arthritis are sometimes associated with bronchiectasis.

WHAT ARE THE SYMPTOMS OF BRONCHIECTASIS?

People with bronchiectasis tend to cough up large amounts of phlegm (or sputum) which is usually sticky and discoloured (green usually). Some people could fill a household glass with sputum each day. The phlegm may be foul-smelling, or streaked with blood. People with bronchiectasis are prone to recurrent chest infections. The build-up of mucus in the bronchial tubes causes narrowing of the tubes, making it more difficult to breathe. This leads to wheezing and shortness of breath, similar to that seen in asthma. You may also notice nasal or sinus problems, including nasal stuffiness and sinus infections. Tiredness and depression are common. Males with primary ciliary dyskinesia tend to be infertile.

HOW DO DOCTORS DIAGNOSE BRONCHIECTASIS?

Your doctor may suspect that you have bronchiectasis from your symptoms, especially the daily production of large amounts of sputum. Your doctor will ask you about any illnesses that may cause bronchiectasis. Your doctor may hear noises called "crackles" when he listens to your lungs with the stethoscope. The first test is usually a chest x-ray which may show abnormal thickened bronchi. Far superior to a plain chest x-ray is a highresolution CT scan of the chest. This is a special x-ray of the lungs that gives detailed pictures, and confirms the diagnosis of bronchiectasis, and its extent.

Samples of your sputum will normally be sent to the laboratory to see what bacteria are growing in it. Breathing tests are normally performed to assess if there is narrowing of the bronchial tubes. Further tests may be performed to find the cause of the bronchiectasis. These include blood tests , and a sweat test (which measures the amount of chloride salt in your sweat) to outrule cystic fibrosis. If primary ciliary dyskinesia is suspected, a piece of tissue (biopsy) may be taken from the inside of the nose or from the lung. This is examined under a microscope to see if the cilia are working properly. The lung biopsy is obtained by performing a bronchoscopy. This procedure can be done as a day case, and is painless and safe. The rare complications that can happen will be explained.

HOW IS BRONCHIECTASIS TREATED?

Firstly, you will be referred to a physiotherapist who will teach you postural drainage. This is a technique which allows sputum to drain from the infected tubes with the assistance of gravity. You will then perform this technique on yourself at home. Chest infections are treated with antibiotics, usually given in tablet form, at home. You may have to come into hospital for a short period for antibiotics given through a drip, if there is a serious infection present. Some people who have very frequent chest infections may require continuous antibiotic treatment at home. Your doctor may vary or rotate these antibiotics to prevent antibiotic resistance developing. A number of people with more severe bronchiectasis grow a bacteria in their lungs called pseudomonas aeruginosa. Once present, this bacteria never goes away, but it is important to keep its growth under control.

This is normally done in one of two ways: either by bringing you into hospital at regular intervals for antibiotics through a drip, or by giving a special antibiotic through a nebuliser at home. Obstruction of airflow can be improved with medications similar to those used in asthma. You may therefore receive inhalers, usually a combination of an inhaled steroid (which reduces lung inflammation) and a bronchodilator (a type of medication that makes the bronchi wider and easier to breathe through). People who have specific causes of bronchiectasis, e.g. cystic fibrosis, require specific forms of treatment. Your doctor will discuss these if appropriate Surgery is now rarely required for bronchiectasis.