Chronic obstructive pulmonary disease (COPD) is a term used to describe chronic lung diseases that cause limitations in lung airflow. The chronic airflow limitation characteristic of COPD is caused by a mixture of small airway disease (obstructive bronchiolitis) and parenchymal destruction (emphysema), the relative contributions of which vary from person to person.
COPD is preventable, but not curable. Treatment can slow the progress of the disease, but it worsens slowly over time. Because of this, it is most frequently diagnosed in people aged 40 years or older. Chronic bronchitis and emphysema are terms that are no longer used and are now included within the COPD diagnosis. It is not a simple smoker’s cough, but an under-diagnosed, life threatening lung disease.
At one time, COPD was more common in men, but because of increased tobacco use among women in high-income countries and the higher risk of exposure to indoor air pollution (such as biomass fuel used for cooking and heating) in low-income countries, the disease now affects men and women almost equally.
If urgent action is not taken to reduce underlying risk factors, especially tobacco use and air pollution, then total deaths from COPD are projected to increase in next twenty years. According to WHO, COPD will move from fifth leading cause of death in 2002, to fourth place in the rank projected to 2030 worldwide.
Symptoms
The most common symptoms of COPD are:
- Breathlessness or a “need for air”
- Abnormal sputum (a mix of saliva and mucus in the airway),
- Chronic cough,
- Daily activities, such as walking up a short flight of stairs or carrying a suitcase, can become very difficult as the condition gradually worsens.
Systemic Features of COPD (extra-pulmonary effects) and co-morbidities:
- Cachexia: loss of fat free mass
- Skeletal muscle wasting
- Osteoporosis
- Depression
- Anemia
- Increased risk of cardiovascular disease
- Lung cancer
- Metabolic diseases and Diabetes mellitus
Stages of COPD- according to symptoms:
Mild COPD – Symptoms of chronic cough and sputum production may be present, but not always. At this stage, the individual is usually unaware that his or her lung function is abnormal.
Moderate COPD- shortness of breath typically developing on exertion and cough and sputum may be present. This is the stage at which patients typically seek medical attention because of chronic respiratory symptoms or an exacerbation of their disease.
Severe COPD– greater shortness of breath, reduced exercise capacity, fatigue, and repeated exacerbations that almost always have an impact on patients’ quality of life.
Very Severe COPD –presence of chronic respiratory failure
Causes
Risk factors for COPD:
(I) Genes: COPD is a polygenic disease. The genetic risk factor that is best documented is a severe hereditary deficiency of alpha-1 antitrypsin.
(II)Environmental factors:
(a)Tobacco smoke: The primary cause of COPD is tobacco smoke (including second-hand or passive exposure). Cigarette smoking is most commonly encountered risk factor for COPD. Apart from cigarettes, people from India smoke tobacco using bidis, hookahs and chillums among several other forms of smoking. Bidis are more harmful than cigarettes (although they contain only one fourth the amount of nicotine, they produce four to five times more tar than cigarettes, making one bidi as harmful as one cigarette), hookahs are more harmful than bidis and the chillum is the most harmful of the lot. Smoking during pregnancy may also pose a risk for the foetus, by affecting lung growth and development of the foetus.
Passive exposure to cigarette smoke (also known as environmental tobacco smoke or ETS) may also contribute to respiratory symptoms and COPD.
(b) Indoor air pollution: Biomass (wood, animal dung, crop residues) and coal are used as the main source of energy for cooking, heating, and other household needs by some communities. In these communities, indoor air pollution is responsible for a greater fraction of COPD risk than smoking or outdoor air pollution. The other common indoor air pollutant is the burning of mosquito coils at homes to get rid of mosquitoes. Burning one mosquito coil in the night emits as much particulate matter pollution, as that is equivalent to around 100 cigarettes.
(c) Outdoor air pollution: Outdoor air pollution mainly from emission of pollutants from motor vehicles and industries is an important public health problem. High levels of urban air pollution are harmful to individuals with existing heart or lung disease.
(d) Occupational dusts and chemicals (such as vapours, irritants, and fumes)
(e) Lung growth and Development-Any factor that affects lung growth during gestation and childhood has the potential for increasing an individual’s risk of developing COPD.
(f) Oxidative Stress (excess of oxidants and/or depletion of antioxidants are termed oxidative stress): An imbalance between oxidants and antioxidants is considered to play a role in the pathogenesis of COPD.
(g) Infections: Infections (viral and bacterial) may contribute to the pathogenesis and progression of COPD. A history of severe childhood respiratory infection has been associated with reduced lung function and increased respiratory symptoms in adulthood. Tuberculosis is recognized as a risk factor for COPD.
(h)Socioeconomic Status: There is evidence that the risk of developing COPD is inversely related to socioeconomic status. It is not clear, however, whether this pattern reflects exposures to indoor and outdoor air pollutants, crowding, poor nutrition, or other factors that are related to low socioeconomic status.
(i)Nutrition: The role of nutrition as an independent risk factor for the development of COPD is unclear. Malnutrition and weight loss can reduce respiratory muscle strength and endurance, apparently by reducing both respiratory muscle mass and the strength of the remaining muscle fibers.
(j)Asthma: Asthma may be risk factor for the development of COPD, although the evidence is not conclusive.
The causes for COPD have opposite patterns according to the geographic areas. In high- and middle-income countries tobacco smoke is the biggest risk factor, meanwhile in low-income countries exposure to indoor air pollution, such as the use of biomass fuels for cooking and heating, is the main risk factor.
Diagnosis
Diagnosis of COPD should be considered in any patient who has symptoms of a chronic cough, sputum production, dyspnoea (difficult or labored breathing) and a history of exposure to risk factors for the disease.
COPD is confirmed by a diagnostic test called “spirometry”. It measures how much air a person can inhale and exhale, and how fast air can move into and out of the lungs. Because COPD develops slowly, it is frequently diagnosed in people aged 40 or older.
Where spirometry is unavailable, clinical symptoms and signs, such as abnormal shortness of breath and increased forced expiratory time, can be used to help with the diagnosis.
Chronic cough and sputum production often precede the development of airflow limitation by many years; although not all individuals with cough and sputum production go on to develop COPD.
Management
An effective COPD management plan includes four components: (1) assess and monitor disease; (2) reduce risk factors; (3) manage stable COPD; (4) manage exacerbations.
Assess and monitor disease:
A clinical diagnosis of COPD should be considered in any patient who has dyspnoea, chronic cough or sputum production, and /or a history of exposure to risk factors for the disease. The diagnosis should be confirmed by spirometry.
Reduce risk factors:
Tobacco smoke, occupational exposures, indoor and outdoor air pollution and irritants are various risk factors for COPD. Reductions of total personal exposure to these risk factors are important goals to prevent the onset and progression of COPD.
(a)Tobacco smoke –
Health care workers should encourage all patients who smoke to quit, even those patients who come to the health care provider for unrelated reasons and do not have symptoms of COPD. Counseling delivered by physicians and other health professionals significantly increases quit rates over self-initiated strategies. Pharmacotherapy is recommended in persons when counseling is not sufficient to help patients quit smoking.
(b)Occupational exposure –The main emphasis should be on primary prevention, which is best achieved by the elimination or reduction of exposures to various substances in the workplace. Secondary prevention, achieved through surveillance and early case detection, is also of great importance.
(c) Indoor and outdoor air pollution- Reduction of exposure to smoke from biomass fuel, particularly among women and children, is a crucial goal to reduce the prevalence of COPD worldwide. Public policy to reduce vehicle and industrial emissions to safe levels is an urgent priority to reduce the development of COPD.
Manage stable COPD:
The overall approach to managing stable COPD should be individualized to manage symptoms and thereby improvement in the quality of life. The approach consists of health education, medications, pulmonary rehabilitation, oxygen therapy, ventilatory support, surgical treatment.
(i)Health education– For patients with COPD, health education can play a role in improving skills, ability to cope with illness, and health status. It is effective in accomplishing certain goals, including smoking cessation. Education also improves patient response to exacerbations.
(ii)Pharmacologic treatment– Pharmacologic therapy is used to prevent and control symptoms, reduce the frequency and severity of exacerbations, improve health status, and improve exercise tolerance.
a) Bronchodilators (medications that cause widening of airway) are given on an as-needed basis or on a regular basis to prevent or reduce symptoms.
b) Glucocorticosteroids:The role of Glucocorticosteroids in the management of stable COPD is limited to specific indications.
c) Other pharmacological treatments–
Vaccines– Influenza vaccines containing killed or live, inactivated viruses are recommended to COPD cases. Pneumococcal polysaccharide vaccine is recommended for COPD patients 65 years and older.
Alpha-1 antitrypsin augmentation therapy– It may be used in young patients with severe hereditary alpha-1 antitrypsin deficiency and established emphysema.
Antibiotics– antibiotics should be used for treating infectious exacerbations of COPD and other bacterial infections.
Mucolytic (mucokinetic, mucoregulator) agents- Although a few patients with viscous sputum may benefit from mucolytics, the overall benefits seem to be very small. Widespread use of these agents is not recommended.
Antitussives- Cough, has a significant protective role, thus the regular use of antitussives is not recommended in stable COPD.
(iii)Non-pharmacologic treatment–
a) Rehabilitation– Comprehensive pulmonary rehabilitation programme includes exercise training, nutrition counseling, and education.
- Exercise training– All patients with COPD benefit from exercise training programs, improving with respect to both exercise tolerance and symptoms of dyspnoea and fatigue.
- (b)Nutrition counseling– Nutritional state is an important determinant of symptoms, disability, and prognosis in COPD; both overweight and underweight can be a problem.
(iv) Oxygen Therapy- Oxygen therapy, one of the principal non pharmacologic treatments for patients with Severe COPD. It can be administered in three ways: long term continuous therapy, during exercise, and to relieve acute dyspnoea.
The long-term administration of oxygen (> 15 h per day) to patients with chronic respiratory failure has been shown to increase survival.
(v)Ventilatory support– Noninvasive ventilation (using either negative or positive pressure devices) is now widely used to treat acute exacerbations of COPD.
(vi)Surgical treatment-
- Bullectomy,
- Lung volume reduction surgery (LVRS),
- Lung transplantation.
(vii) Manage exacerbations:
Exacerbations of respiratory symptoms requiring medical intervention are important clinical phases in COPD. The most common causes of an exacerbation are infection of the tracheobronchial tree and air pollution, but the cause of approximately one-third of severe exacerbations cannot be identified.
Inhaled bronchodilators (particularly inhaled B2-agonists or anticholinergics), theophylline, and systemic, preferably oral, glucocorticosteroids are effective for treatments for acute exacerbations of COPD.
Patients experiencing COPD exacerbations with clinical signs of airway infection (e.g., increased volume and change of color of sputum, or fever) may benefit from antibiotic treatment.
Noninvasive positive pressure ventilation (NIPPV) in acute exacerbations improves blood gases and pH (a measure of acidity and alkalinity), reduces in-hospital mortality, decreases the need for invasive mechanical ventilation and intubation, and decreases the length of hospital stay.
Complications
(a)Hypoxemia- It is low concentration of oxygen in blood.
(b)Cor pulmonale-Progressive pulmonary hypertension may lead to right ventricular hypertrophy and eventually to right-side cardiac failure (cor pulmonale).
(c) Exacerbations–
An exacerbation of COPD is defined as an event in the natural course of the disease characterized by a change in the patient’s baseline dyspnoea, cough, and/or sputum that is beyond normal day-to-day variations. It is acute in onset, and may warrant a change in regular medication in a patient with underlying COPD.
The most common causes of an exacerbation are infection of the tracheobronchial tree and air pollution, but the cause of about one-third of severe exacerbations cannot be identified.
Causes of death in patients with COPD are mainly cardiovascular diseases, lung cancer, and, in those with advanced COPD, respiratory failure.
Prevention
Primary prevention (Prevent COPD before it starts):
Primary prevention of COPD requires the reduction or avoidance of personal exposure to common risk factors (Tobacco smoke, occupational exposures, indoor and outdoor air pollution and irritants), to be started during pregnancy and childhood.
Direct and indirect exposure to tobacco smoke should be avoided.
Other shared risk factors that include low birth weight, poor nutrition, acute respiratory infections of early childhood, indoor and outdoor air pollutants, and occupational risk factors should be addressed.
The population and individual at risk must be fully informed about a healthy lifestyle, such as healthy nutritional habits, regular exercise and avoidance of tobacco, airway irritants and allergens. Those who are at high risk should avoid vigorous exercise outdoors during pollution episodes. Other sectors within a community must be actively engaged.
Secondary and tertiary prevention:
Secondary and tertiary prevention which involves early detection of COPD cases, smoking cessation, pulmonary rehabilitation and reduction of personal exposure to noxious particles and gases can reduce symptoms, improve quality of life, and increase physical fitness. It helps in slow progression of COPD and its complications.
Use of Influenza vaccination and Pneumococcal Vaccination in COPD cases helps in decreasing exacerbations.
Persons with advanced COPD should monitor public announcements of air quality and staying indoors when air quality is poor may help reduce their symptoms.
References-
www.who.int/mediacentre/factsheet
www.who.int/respiratory/copd/burde
www.who.int/respiratory/copd/en/
www.who.int/gard/publications/chronic