Chronic Obstructive Pulmonary Disease (COPD)
Chronic Obstructive Pulmonary Disease (COPD) is the name for a spectrum of chronic lung diseases, including chronic bronchitis and emphysema, characterised by obstruction of airflow. The most common symptoms are breathlessness and persistent “wet” (sputum-producing) cough.
As it takes years for the inflammation in the lungs to have an effect, COPD is primarily a disease of the elderly, affecting adults over 45.
All of us experience a decline in lung function with age, as our lungs lose elasticity. However, in COPD patients, inflammation within the lung leads to more rapid deterioration. As the condition worsens, even daily activities such as walking up a short flight of stairs, washing or dressing become difficult. In their final years, patients are severely short of breath, often unable to lead a normal life, and need to access healthcare services regularly.
COPD is a major global health problem. Five percent of global deaths are estimated to be due to this disease; 90% occur in low and middle-income countries. Figures are rising alarmingly, especially among women, and it’s estimated that COPD will be the 3rd leading cause of death globally by the year 2030.
It seems that chronic inhalation of noxious particles and gases stimulates inflammation in the lung. The white blood cells, which are the body’s defence mechanism against invasive substances, start attacking normal lung tissue. Unlike the acute inflammation of infection or trauma, this inflammation smoulders on for decades, resulting in progressive damage.
Cigarette smoking is the major risk factor for COPD, and much of the increase in COPD is associated with increased tobacco use, especially in the developing world. Starting smoking at a young age, the "total pack years" (the number of cigarettes smoked per year multiplied by the number of years of smoking) and the person's current smoking status all contribute to respiratory impairment.
However, only an estimated 20% of smokers develop the disease, and many cases of COPD occur in non-smokers.
Other risk factors for the development of COPD include:
- Environmental tobacco smoke exposure (passive smoking)
- Exposure to smoke from coal and wood fires
- Exposure to dust, chemicals, fumes and vapours
- Outdoor air pollution
- Childhood illness
- Tuberculosis (TB)
- Respiratory infections
- Genetic susceptibility
- Poor lung growth and development
- Poor nutrition
- Low socio-economic status
Several risk factors may have a combined effect to increase the likelihood of the disease. For example, low socio-economic status may entail other risk factors, such as childhood illness, TB, and the indoor burning of coal and wood. HIV infection, either alone or together with other opportunistic infections, may be an independent risk factor for the development of COPD.
In the early phases of COPD, symptoms may be slight or unrecognised. Patients may have respiratory symptoms, like cough with sputum production, but may have no exercise impairment or may not be physically active enough for their shortness of breath to become evident. The majority of COPD patients (up to 70%) therefore remain undiagnosed.
Depending on which part of the lung is affected, patients may develop one or both of two sub-types of COPD:
- Chronic bronchitis – when the inflammation affects mainly the large airway walls, leading to mucus over-production and swelling of the inner layers of the airways, causing obstruction to airflow.
- Emphysema – when the damage involves the tiny sacs in the lungs called alveoli, responsible for oxygen uptake. This damage can cause severe exercise impairment.
Destruction of the fine elastic fibres that support lung tissue leads to an inability to empty the lungs normally. Thickening of the bronchial walls, formation of scar tissue and destruction of the alveoli all impair airflow, the uptake of oxygen and the removal of carbon dioxide.
The disease is not confined to the lungs; it has systemic (whole-body) effects that result in, for example, weight and appetite loss, and particularly a decrease of muscle mass in the limbs of severely ill patients.
When the inflammatory response has, over years, caused extensive damage, patients may experience conditions that require hospitalisation:
- Respiratory failure. A blue tongue and lips indicate severe impairment of oxygen uptake.
- Heart failure. Failure of the right ventricle of the heart is characterised by swollen ankles and legs, an enlarged liver and elevated neck veins.
Symptoms are frequently precipitated or exacerbated (made worse) by a respiratory infection, usually during the wintertime when influenza and colds are endemic. COPD patients may become acutely ill. Smokers usually have a much longer recovery time than non-smokers and experience more severe symptoms during acute exacerbations of COPD.
Acute exacerbations are characterised by marked worsening of the symptoms of COPD, including:
- Increased shortness of breath
- Increased wheezing
- Increased sputum production
- Change in sputum colour (often becoming yellow or green)
- In severe cases, respiratory or heart failure
COPD should be considered in any patient who has a chronic cough, sputum production, shortness of breath and/or a history of exposure to risk factors. If diagnosed early, patients can take preventative measures.
However, because symptoms can be slight, regular measurement of lung function in at-risk patients can be the only way to detect the disease in its early stages.
Lung function is measured by spirometry: a test in which patients are asked to breathe fully in and out, as fast as they can. Measurements include the amount of air blown out in one second, the total amount of air blown out, and ratio between the two. Normal lungs can almost completely empty in one second, but when airflow obstruction is present, the time taken to empty the lungs is longer.
There are ways to control COPD symptoms, prevent exacerbations and improve quality of life. Quitting smoking is the most important of these: it is the only significant intervention that can slow the decline in lung function. Secondary cigarette smoke can also be avoided, as well as exposure to noxious fumes, gases and dust.
Further treatment of COPD will depend on its severity. (COPD can be classified as mild, moderate, severe or very severe.) Medications include:
These include anticholinergics and beta-agonists, both available in short or long-acting preparations, and oral theophylline. Where short-acting bronchodilators alone or in combination are insufficient, or with more advanced disease, long-acting inhaled bronchodilators can be added.
Chronic antibiotic therapy may help patients with a chronic bronchial infection called bronchiectasis.
Oral and inhaled corticosteroids
For patients with continuing symptoms, advanced disease or repeated exacerbations, inhaled corticosteroids can be added. Many patients with severe COPD will take long-acting anticholinergics, long-acting beta-agonists and inhaled corticosteroids – so-called “triple-inhaler therapy”.
Patients with COPD need to be protected from respiratory infections. They should be vaccinated against the predominant viral strains every year – in particular seasonal and pandemic influenzas. All patients with chronic respiratory disease should also receive a pneumococcal vaccination every 5 - 10 years.
Other treatments may include:
- Enhanced nutrition. More than 30% of patients with COPD have protein-calorie malnutrition, and loss of weight is an important symptom in late-stage COPD. High-calorie diets and appetite stimulants have been used in an effort to combat malnutrition.
- Pulmonary rehabilitation. This involves strengthening the arm and leg muscles, as well as the muscles of respiration. This enables patients to cope with moderate exercise and to carry on with their daily routine in spite of loss of lung function and low blood-oxygen concentrations.
- Long-term oxygen therapy. All patients with severe COPD feel better on oxygen, and this therapy has been shown to decrease mortality in patients with chronically low blood-oxygen concentrations. However, the provision of home oxygen is expensive, and it is vital that patients on this therapy have stopped smoking.
- Lung volume reduction surgery. This can be of benefit to certain patients who have predominantly upper-lobe emphysema, low exercise capacity and no other serious disease. The surgery works by excising parts of the lung, allowing the adjacent non-involved lung to inflate better.
In exacerbated COPD, treatment may include: oxygen therapy for hypoxia; bronchodilators to improve airflow; antibiotics for 7 - 14 days to reduce infection and phlegm production; oral or injected corticosteroids for 5 - 10 days to reduce inflammation; non-invasive ventilation in the case of respiratory failure; and mechanical ventilation in ICU if the above measures fail.
Public education about COPD risk factors is crucial in prevention. Preventing smoking at school level is a much more cost-effective method of combating the disease than trying to convert smokers, or treating symptoms when they occur.
In a number of occupations, including mining and industry, enforcement of protective measures –such as wearing masks and monitoring levels of dust and toxic fumes – have minimised and in some cases abolished the danger of industrial exposure.
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