NHS Direct Online Health EncyclopaediaEncyclopaedia Topic: Bronchitis

Introduction

Bronchitis is an inflammation of the lining of the air tubes of the lungs, the bronchi. Acute bronchitis usually followsa cold, a sore throat or influenza, most often in winter. It is very common as a winter flare-up in people withchronic bronchitis. It may also be brought on by breathing a polluted atmosphere or by smoking.

In most cases the condition settles within a week or two, but there is always the risk, especially in cigarettesmokers, that the condition may progress to chronic bronchitis with inevitable winter flare-ups.

The lining cells of the air tubes in healthy lungs are tall (columnar). The surfaces nearest the inside of the tube arecovered with fine hairs (cilia), which move together in a manner similar to the effect of wind blowing across a fieldof ripe corn.

The hair movement acts to carry dust and other foreign material upwards and away from the deeper parts of thelungs. This is one of the bodys protective processes and, without it, a good deal of unwanted material in the airwe breathe would find its way into the delicate air sacs.

Chemical irritants such as cigarette smoke or other environmental or industrial pollutants damage the ciliatedcells, eventually destroying the action of the hairs altogether. They also cause the glands in the air passages toproduce too much mucus. Because the cilia are not working properly, this mucus accumulates in the tubes.Coughing can usually clear this material. Irritants also interfere with the white blood cell mechanism that combatsinfection in the lungs. This is the condition of chronic bronchitis.

Coughing often becomes less effective when the circular muscles in the wall of the bronchial tubes contract, socausing the tubes to narrow. This is called bronchospasm and causes wheezing, another sign of chronicbronchitis.

Chronic bronchitis is one of the forms of chronic obstructive lung (pulmonary) disease (COPD).In the early stageschronic bronchitis may be a comparatively mild disease. But, with time and continued abuse, it is likely to progressto chronic obstructive airway disease (COAD), in which large numbers of the tiny lung air sacs break down to forma smaller number of larger air spaces. The total surface area now available for transferring oxygen to the blood ismuch less, so you become short of oxygen. In addition, the smaller bronchial tubes become inflamed, narrowedand partially blocked by mucus. The result is increased breathlessness.

Smoking is especially dangerous if you have a persistent, productive cough. Chronic bronchitis and other forms ofCOPD affects 18 per cent of male smokers and 14 per cent of female smokers.

Chronic bronchitis and emphysema may so restrict the movement of oxygen from the atmosphere to your bloodthat the blood does not get enough. Blood without enough oxygen is blue, in contrast to its usual bright red colour,and gives a bluish tinge to the skin. This is called cyanosis.At the same time, these diseases may greatly increasethe resistance to blood pumped through the lungs by the right side of the heart. This causes the muscle of theright heart to enlarge, and this extra pumping power may meet the need for a while.

Eventually, however, the right side of the heart may fail and be unable to maintain enough blood flow from the rest

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of the body, via the veins. The result is a general increase of fluid in the tissues (oedema), characteristic of rightheart failure.

Symptoms

The symptoms of acute bronchitis usually develop quickly over 24-48 hours and may include:

An irritating, persistent cough that is at first dry but later with increasing production of clear sputum. Central chest pain on coughing. Breathlessness, tightness of the chest and wheezing. Slight fever. Blood-streaked sputum is fairly common and does not necessarily, or even usually, mean that something

potentially life-threatening is happening. In about 80 per cent of cases it is a sign of bronchitis.

Those with a long-term heart or lung disease or those who cough up discoloured sputum, indicating a secondaryinfection, should contact the GP.

Causes

Acute bronchitis in a previously healthy person is usually caused by a viral infection, such as a common cold thathas spread from the nose, throat, or sinuses.

However smokers and those who have an existing lung disorder, or those who are exposed to high levels ofindustrial atmospheric pollution, are more prone to attacks.

Diagnosis

The diagnosis is made on the basis of the symptoms, the sputum and the response to treatment.

In chronic bronchitis, there are flare-ups every winter, and often at other times. Cough with sputum productionoccurs on most days for at least three months of the year. Chronic bronchitis is virtually confined to cigarettesmokers.

A stethoscope will reveal added sounds. Superimposed on the breath sounds are wheezes, crackles and musicalnotes of different pitches indicating spasm of the bronchial tubes.

Peak expiratory flow measurement is a test widely used to assess the degree of any kind of obstruction to the airpassages, especially of the kind caused by asthma and chronic bronchitis. The test gives a valuable indication ofthe severity of the disease and of response to treatment.

Usually an individual who breathes out as forcibly as possible through the mouth, the rate of flow of air risesrapidly to a peak and then declines steadily to zero. Usually there is a peak breathe out rate of up to 8 litres asecond, but in certain lung diseases, such as bronchitis, the figure is much lower because the bronchial tubes arenarrow or partially blocked.

Provided there is no gross weakness in the respiratory muscles, a lowered peak flow rate indicates probabledisease of the air passages. This could be asthma, bronchitis or bronchiectasis, or a lung disorder, such asemphysema or fibrosis that affects the natural recoil of the lungs.

Treatment

Acute bronchitis, in a previously healthy person is caused by a viral infection and usually resolves itself within afew days. Any secondary infection is treated with antibiotics and usually responds well. Taking painkillers, such as

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paracetamol, may be suggested. It is important to give up smoking.

There is no cure for chronic bronchitis, but healthy living, especially the avoidance of smoking, will help.

Various other drugs can improve symptoms:

Acetylcysteine is a drug used to reduce the stickiness and viscosity of mucus. It is known as a mucolytic, and is useful for freeing sputum in bronchitis. Rimiterol is a bronchodilator drug used in the treatment of bronchitis. Salbutamol is another bronchodilator drug used to treat chronic bronchitis. Sulfametopyrazine is a sulphonamide drug taken weekly to control infection in chronic bronchitis.

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