What is Chronic obstructive pulmonary disease ?
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.
Chronic obstructive pulmonary disease 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
Chronic obstructive pulmonary disease 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.
Chronic obstructive pulmonary disease 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.
Chronic obstructive pulmonary disease 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.
Chronic obstructive pulmonary disease 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. The National Tobacco Control Programmewas launched by Ministry of Health and Family Welfare (MoHFW), Government of India in 2007- 08, with the objective to bring about greater awareness about the harmful effects of tobacco use and Tobacco Control Laws.
Under the Quit Tobacco Programme supported by Government of India, mobile technology is being utilized in an initiative named as “mCessation Programme- QUIT TOBACCO FOR LIFE”. The aim of this programme is to reach out and support the tobacco users of all categories who want to quit tobacco use.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.