Chronic obstructive pulmonary disease (COPD)

• What is Chronic Obstructive Pulmonary Disease (COPD)
• Statistics on Chronic Obstructive Pulmonary Disease (COPD)
• Risk Factors for Chronic Obstructive Pulmonary Disease (COPD)
• Progression of Chronic Obstructive Pulmonary Disease (COPD)
• Symptoms of Chronic Obstructive Pulmonary Disease (COPD)
• Clinical Examination of Chronic Obstructive Pulmonary Disease (COPD)
• How is Chronic Obstructive Pulmonary Disease (COPD) Diagnosed?
• Prognosis of Chronic Obstructive Pulmonary Disease (COPD)
• How is Chronic Obstructive Pulmonary Disease (COPD) Treated?
• Chronic Obstructive Pulmonary Disease (COPD) References

What is Chronic Obstructive Pulmonary Disease (COPD)

Chronic obstructive pulmonary disease (COPD) is a disease of the lung. The lungs are the organs found in the chest which are invloved in breathing. Air enters the nose and mouth, then travels to the lungs via the trachea, which divides into smaller airways called bronchi and, subsequently, bronchioles. (See diagram below). The lung tissue itself is a spongy material, consisting of a series of folded membranes (the alveoli) which are located at the ends of very fine branching air passages (bronchioles). COPD is a disease of the smaller airways in the lungs.

Chronic obstructive pulmonary disease (COPD) is a disease that consists of two pathologies:

1. Chronic bronchitis: Defined as chronic cough with mucous production on most days for greater than three months, for at least two consecutive years.
2. Emphysema: Defined as an enlargement of the alveoli and bronchioles, and destruction of the alveolar walls.

These disease processes affect the bronchi and alveolar walls, respectively. The end result of both is the destruction of lung tissue and obstruction of the airways of the lung, leading to impaired gas exchange. The two conditions usually occur together, causing chronic airflow limitation.

Other names for chronic obstructive pulmonary disease (COPD) include chronic obstructive airways disease (COAD), chronic obstructive lung disease (COLD) and chronic airflow limitation (CAL).

Statistics on Chronic Obstructive Pulmonary Disease (COPD)

Chronic obstructive pulmonary disease (COPD) is a major cause of disability, hospital admissions, and mortality in Australia. It is considered to be ranked third in the overall burden of disease (following heart disease and stroke). More than half a million Australians are estimated to suffer from moderate to severe disease. COPD ranks fourth among the common causes of death in Australian men, and sixth in women. The death rates from COPD in Indigenous Australians are up to five times that of non-Indigenous Australians.

The major cause of COPD is smoking. It is thought that around 10-15% of smokers will develop the disease. Furthermore, as rates of smoking-related diseases are increasing in women, it is thought that rates of COPD will also increase in women, perhaps eventually exceeding rates in men.

Risk Factors for Chronic Obstructive Pulmonary Disease (COPD)

• Cigarette smoke is by far the most important factor in the development of COPD. If you smoke 30 cigarettes per day, you are 20 times more likely to die from COPD than non-smokers. The more you smoke, the greater your risk of severe disease. Smoking a pack a day for more than 20 years is considered a significant risk in the development of COPD. COPD is therefore largely preventable if you do not smoke.
• Familial factors: A family history of COPD may increase your risk of having the disease. This may relate to hyper-reactive airways, a feature of asthma.
• Alpha-1-antitrypsin deficiency: This substance is found in several places throughout the body and is important in preventing cells from breaking down, particularly those in the lungs and liver. People who do not have enough of this enzyme are at increased risk of emphysema and cirrhosis of the liver.
• Exposure to air pollution.
• Recurrent airway infections: This may be important in the development and progression of COPD. Prompt use of antibiotics and vaccinations may help reduce the impact of infections.
• Other factors such as urbanization, social class, occupation and diet may also have some impact in the development of COPD, but their overall effect is not known.

Progression of Chronic Obstructive Pulmonary Disease (COPD)

In susceptible smokers, cigarette smoking results in a steady decline in the ability of the lungs to function. Stopping smoking, even late in the course of the disease, may result in mild improvement in lung function and, more importantly, will slow the rate of decline in lung function. Sometimes your lung function can improve back up to the level of a non-smoker.

COPD usually starts when you are in your 50s or 60s. From this point, there is a slow and steady decline in lung function. This can eventually cause disability and impairments, but these are often unrecognised until late in the disease. It is likely that you will require long-term medication treatment. Note that if you are a smoker you may also suffer from lung cancer and cardiovascular disease (such as ischaemic heart diseases) on top of your COPD.

COPD can cause a number of complications:

• Secondary polycythaemia: This is an increase in the number of red blood cells in the blood to try to compensate for reduced oxygen levels. The blood subsequently becomes ‘thicker’ with sluggish flow which can lead to clotting;
• Right heart failure;
• Pneumothorax: This is leakage of air from the lung into the surrounding pleural space due to rupture of a bulla (dilated air space). This can lead to collapse of the lung and may require insertion of a chest drain;
• Respiratory failure: This is often caused by acute infective exacerbations. Death can sometimes occur from a severe decline in respiratory function.

Symptoms of Chronic Obstructive Pulmonary Disease (COPD)

The most common symptoms of COPD include cough, sputum production, wheeze and progressive breathlessness. Usually these symptoms develop gradually over several years before you even notice them. Often patients with COPD go to their doctor due to an acute illness or exacerbation, but careful questioning may reveal that these symptoms may have been present for a longer time. Your doctor will ask you detailed questions about the characteristics of your symptoms, their onset, duration and any precipitating factors.

Patients with COPD often have a smoker’s cough prior to the development of other symptoms. It is important that your doctor knows your smoking history as this helps the diagnosis, and also determines your risk of other disorders such as lung cancer. Certain activities may make you more breathless than others. In particular, activities involving arm movements above the shoulders (such as painting the roof) are difficult for patients with COPD. Walking on a treadmill or pushing a shopping trolley are sometimes easier as they allow you to brace your arms and chest and use other accessory respiratory muscles.

If your disease is advanced, even simple activities of daily living such as dressing can lead to severe breathlessness. Other symptoms may include susceptibility to colds and respiratory infections, and you may notice your breathlessness is worsened by foggy weather and pollution.

Clinical Examination of Chronic Obstructive Pulmonary Disease (COPD)

Your doctor will perform a detailed examination of your respiratory system. This will include undressing your top, inspecting your chest, measuring your chest expansion and listening to your breath sounds. Important signs your doctor will be looking for include:

• Tachypnoea (rapid breathing);
• Prolonged expiratory phase of respiration;
• Use of accessory muscles of respiration, with intercostal in-drawing and pursing of lips on expiration;
• Reduced chest expansion;
• Hyperinflation: Your chest may become barrel-shaped due to air trapping. The front to back distance becomes larger, and the lungs may become so big they overlap the heart and push down the liver;
• Wheeze: This is a musical type sound heard by the doctor through the stethoscope. It represents airway obstruction. Usually wheeze will be heard widely throughout your chest. This may be the only sign in early disease;
• Signs of heart failure, such as peripheral oedema (swelling), may be present in advanced disease;
• Evidence of smoking, such as odour or nicotine staining of the fingernails or teeth.

Patients with COPD are often divided into two classes based on their clinical findings.

Patients with chronic bronchitis are classically described as “blue bloaters” due to the presence of cyanosis (blue discolouration) and oedema. They have reduced levels of ventilation and are not very breathless. There are low levels of oxygen in the blood and high levels of carbon dioxide, which can cause other signs, such as bounding pulse, asterixis (flapping of the hands) and, in severe cases, confusion and growing drowsiness.

Patients with predominantly emphysema, on the other hand, are described as “pink puffers” as they are very breathless and hyperventilate (with pursed lips), but have near normal levels of oxygen and carbon dioxide in the blood. However, these clinical signs aren’t always reliable and do not always correlate with pathology.

How is Chronic Obstructive Pulmonary Disease (COPD) Diagnosed?

Your doctor may perform number of tests to confirm the diagnosis of COPD and determine the severity of airway limitation. Tests may include:

• Blood tests: Specifically looking at the concentration of red blood cells. Haemoglobin levels and the concentration of red blood cells may be increased due to the chronic lack of oxygen in the body (an attempt at compensation). This process is called secondary polycythaemia;
• Chest x-ray: This helps to show hyper-expansion of the lungs. The lung fields will look enlarged and empty and may flatten out the diaphragm. The doctor may also see bulla (dilated airspaces) from emphysema;
• ECG or Echocardiogram: These tests can detect signs of right heart failure (a complication of COPD);
• Lung function tests: Spirometry is the best test to detect airflow limitation and obstruction. Unlike asthma, the airflow limitation is COPD is largely irreversible;
• Blood gases: These may also be normal, but in the later stages of disease you may have low oxygen and high carbon dioxide levels;
• High resolution CT: This is sometimes used in patients with COPD. It is best for detecting emphysema and bullae (big dilated air spaces).

Prognosis of Chronic Obstructive Pulmonary Disease (COPD)

The prognosis of COPD is dependent on a number of factors. The degree of impairment of lung function (measured as FEV1) is probably the most important predictor of mortality. As forementioned, ceasing smoking is the best thing you can do to improve your lung function and chance of survival. Studies have shown that even in the most advanced disease, stopping smoking improves your symptoms and prognosis.

In addition, the presence of complications such as heart failure, respiratory failure and exacerbations are also important in your overall prognosis. In general, COPD is a severe and progressive disease, eventually leading to significant disability and reduced survival. Only about half of patients are still alive five years after the diagnosis of COPD. Death may be due to heart failure or infective exacerbations.

How is Chronic Obstructive Pulmonary Disease (COPD) Treated?

The majority of treatments for COPD are used to improve symptoms. Only quitting smoking and oxygen therapy in patients with advanced disease have actually been shown to alter the course of disease and improve survival. An overview of possible treatments that may be used for your COPD is outlined below:

Quitting smoking

Stopping smoking is the best thing you can do for your health and is considered the most important factor in treatment of COPD. Quitting smoking, regardless of the stage and severity of your disease, will slow down the rate of progression of disease, improve your symptoms and prolong your survival. Your doctor will provide you with education and advice on the importance of quitting smoking. They can also prescribe a drug called bupropion and nicotine replacement therapy (as patches, gum, lozenges, etc) to reduce your cravings. It is also beneficial to be involved in counselling and other supportive measures.

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Drug therapy

Drugs can be used for long-term suppression of symptoms or for treatment of acute exacerbations. Bronchodilators and corticosteroids are used to control symptoms. Your doctor will usually give you a trial of oral steroids to see if you respond before using long-term inhaled steroids. Antibiotics are taken for short-term exacerbations of disease. Your doctor may also prescribe agents to reduce the thickness of your sputum (called mucolytics). Studies have shown these agents may reduce the frequency of exacerbations.

If you have alpha-1-antitrypsin deficiency, you may also be treated with weekly or monthly injections of alpha-1-antitrypsin. However, it is not yet proven whether or not this treatment alters the course of disease.  

Pulmonary rehabilitation

Chest physiotherapy has been shown to help remove fluid in the airways. Various techniques are available such as steam inhalation, which assists sputum removal and improves your ventilation. Your doctor will also enter you into exercise or pulmonary rehabilitation programs which have been shown to increase exercise tolerance, relieve symptoms and improve your quality of life.

Oxygen therapy

If you have severe airflow limitation you may require home oxygen therapy, sometimes for up to 19 hours per day. Oxygen can be administered via nasal prongs (small plastic tubes into your nose) or via a mask. This treatment has been shown to prolong life in patients with severe COPD who have stopped smoking. The best benefit from oxygen treatment is obtained if you have quit smoking. Furthermore, oxygen is flammable, so smoking is in fact dangerous during this treatment.

Surgery

If you have severe COPD which is predominantly of the emphysema form, you may benefit from surgery on your lungs. Different operations are available such as bullectomy (which removes large, dilated bullae compressing on the rest of the lung) and lung reduction surgery (which removes severely affected areas of lung and can improve the elasticity of the remaining lung). Very rarely, patients with severe and terminal disease may get a lung transplantation. In appropriate patients, surgery can improve symptoms, enhance lung function and reduce mortality. Your doctor will be able to discuss whether surgery is suitable for you and your disease characteristics.

Other

• Vaccinations: It is important that you have your yearly influenza vaccination, and pneumococcal vaccine. This will help reduce effective exacerbations from these infections;
• Diuretics: If your chronic bronchitis is complicated by right heart failure, you may be treated with tablets to remove the excess fluid;
• Acute exacerbations of COPD: Acute attacks should be treated with bronchodilators, supplemental oxygen, antibiotics and glucocorticoids;
• Depression: COPD is a chronic disease that may lead to significant disability, so some patients may become depressed. Counselling and antidepressant medications may help you overcome this;
• Weight control: It is important that you maintain a healthy weight and nutrition. In advanced disease you may notice marked weight loss. You should have a high fat content and nutritious diet to prevent muscle wasting. Alternatively, if you are markedly overweight or obese you should try to reduce your weight to a healthy range with diet an exercise, in order to reduce demands on your lung function.

Chronic Obstructive Pulmonary Disease (COPD) References

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