Chronic bronchitis is typi?ed by chronic productive cough for at least three months in two successive years (provided other causes such as TUBERCULOSIS, lung cancer and chronic heart failure have been excluded). The characteristics of emphysema are abnormal and permanent enlargement of the airspaces (alveoli) at the furthermost parts of the lung tissue. Rupture of alveoli occurs, resulting in the creation of air spaces with a gradual breakdown in the lung’s ability to oxygenate the blood and remove carbon dioxide from it (see LUNGS). Asthma results in in?ammation of the airways with the lining of the BRONCHIOLES becoming hypersensitive, causing them to constrict. The obstruction may spontaneously improve or do so in response to bronchodilator drugs. If an asthmatic patient’s airway-obstruction is characterised by incomplete reversibility, he or she is deemed to have a form of COPD called asthmatic bronchitis; su?erers from this disorder cannot always be readily distinguished from those people who have chronic bronchitis and/ or emphysema. Symptoms and signs of emphysema, chronic bronchitis and asthmatic bronchitis overlap, making it di?cult sometimes to make a precise diagnosis. Patients with completely reversible air?ow obstruction without the features of chronic bronchitis or emphysema, however, are considered to be su?ering from asthma but not from COPD.
The incidence of COPD has been increasing, as has the death rate. In the UK around 30,000 people with COPD die annually and the disorder makes up 10 per cent of all admissions to hospital medical wards, making it a serious cause of illness and disability. The prevalence, incidence and mortality rates increase with age, and more men than women have the disorder, which is also more common in those who are socially disadvantaged.
Causes The most important cause of COPD is cigarette smoking, though only 15 per cent of smokers are likely to develop clinically signi?cant symptoms of the disorder. Smoking is believed to cause persistent airway in?ammation and upset the normal metabolic activity in the lung. Exposure to chemical impurities and dust in the atmosphere may also cause COPD.
Signs and symptoms Most patients develop in?ammation of the airways, excessive growth of mucus-secreting glands in the airways, and changes to other cells in the airways. The result is that mucus is transported less e?ectively along the airways to eventual evacuation as sputum. Small airways become obstructed and the alveoli lose their elasticity. COPD usually starts with repeated attacks of productive cough, commonly following winter colds; these attacks progressively worsen and eventually the patient develops a permanent cough. Recurrent respiratory infections, breathlessness on exertion, wheezing and tightness of the chest follow. Bloodstained and/or infected sputum are also indicative of established disease. Among the symptoms and signs of patients with advanced obstruction of air?ow in the lungs are:
RHONCHI (abnormal musical sounds heard through a STETHOSCOPE when the patient breathes out).
marked indrawing of the muscles between the ribs and development of a barrel-shaped chest.
loss of weight.
CYANOSIS in which the skin develops a blue tinge because of reduced oxygenation of blood in the blood vessels in the skin.
bounding pulse with changes in heart rhythm.
OEDEMA of the legs and arms.
Some patients with COPD have increased ventilation of the alveoli in their lungs, but the levels of oxygen and carbon dioxide are normal so their skin colour is normal. They are, however, breathless so are dubbed ‘pink pu?ers’. Other patients have reduced alveolar ventilation which lowers their oxygen levels causing cyanosis; they also develop COR PULMONALE, a form of heart failure, and become oedematous, so are called ‘blue bloaters’.
Investigations include various tests of lung function, including the patient’s response to bronchodilator drugs. Exercise tests may help, but radiological assessment is not usually of great diagnostic value in the early stages of the disorder.
Treatment depends on how far COPD has progressed. Smoking must be stopped – also an essential preventive step in healthy individuals. Early stages are treated with bronchodilator drugs to relieve breathing symptoms. The next stage is to introduce steroids (given by inhalation). If symptoms worsen, physiotherapy – breathing exercises and postural drainage – is valuable and annual vaccination against INFLUENZA is strongly advised. If the patient develops breathlessness on mild exertion, has cyanosis, wheezing and permanent cough and tends to HYPERVENTILATION, then oxygen therapy should be considered. Antibiotic treatment is necessary if overt infection of the lungs develops.
Complications Sometimes rupture of the pulmonary bullae (thin-walled airspaces produced by the breakdown of the walls of the alveoli) may cause PNEUMOTHORAX and also exert pressure on functioning lung tissue. Respiratory failure and failure of the right side of the heart (which controls blood supply to the lungs), known as cor pulmonale, are late complications in patients whose primary problem is emphysema.
Prognosis This is related to age and to the extent of the patient’s response to bronchodilator drugs. Patients with COPD who develop raised pressure in the heart/lung circulation and subsequent heart failure (cor pulmonale) have a bad prognosis.... Medical Dictionary
– masses of fat, in consequence of such an injury as a fractured bone, ?nding their way into the circulation and stopping the blood in its passage through the lungs. (See also PULMONARY EMBOLISM.)... Dictionary of Tropical Medicine
Static lung volumes and capacities can be measured: these include vital capacity – the maximum volume of air that can be exhaled slowly and completely after a maximum deep breath; forced vital capacity is a similar manoeuvre using maximal forceful exhalation and can be measured along with expiratory ?ow rates using simple spirometry; total lung capacity is the total volume of air in the chest after a deep breath in; functional residual capacity is the volume of air in the lungs at the end of a normal expiration, with all respiratory muscles relaxed.
Dynamic lung volumes and ?ow rates re?ect the state of the airways. The forced expiratory volume (FEV) is the amount of air forcefully exhaled during the ?rst second after a full breath – it normally accounts for over 75 per cent of the vital capacity. Maximal voluntary ventilation is calculated by asking the patient to breathe as deeply and quickly as possible for 12 seconds; this test can be used to check the internal consistency of other tests and the extent of co-operation by the patient, important when assessing possible neuromuscular weakness a?ecting respiration. There are several other more sophisticated tests which may not be necessary when assessing most patients. Measurement of arterial blood gases is also an important part of any assessment of lung function.... Medical Dictionary
– and the embolism lodges in the pulmonary (lung) circulation. PULMONARY EMBOLISM is a potentially fatal condition and requires urgent anticoagulant treatment (see ANTICOAGULANTS) and sometimes surgery. Extended periods lying in bed or prolonged sitting in a con?ned position such as a car or aeroplane can cause DVT; venous thromboses in the legs may occur after surgery and preventive anticoagulant treatment with HEPARIN and warfarin is often used. Similar treatment is needed if a thrombus develops. STREPTOKINASE is also used to treat thromboembolism.... Medical Dictionary