Medicine
(Department)
Chronic obstructive pulmonary disease
Introduction of Chronic Obstructive Pulmonary Disease (COPD)
COPD is among the commonly occurring lung diseases in which the person feels difficulty in breathing (Lynn, Harrold, and Schuster, 2011). There are two main types of COPD:
- Chronic bronchitis in which there is a persistent cough with mucus,
- Emphysema in which there is damage to the lungs with the passage of time.
Most of the patients of COPD have a combination of both of the conditions.
Causes and reasons of COPD
Smoking is found to be among the top most important causes of COPD. Moreover, chances of developing COPD increases with increased smoking. However, in rare cases people may smoke for years and never develop COPD. On the other hand, it has also been found that nonsmokers, who don’t have the protein known as alpha-1 antitrypsin can have the problem of emphysema (Hillerdal and Mindus, 2011). Other risk factors for COPD may include;
- Exposure of the person to certain fumes or gases in the workplace,
- Exposure of the person to large amounts of smoke from other smokers or from pollution, or
- Regular use of cooking fire without any appropriate ventilation
Pathophysiology of COPD
In COPD, there is chronic inflammation of the airways, pulmonary blood vessels, and the lung tissues. This inflammation is caused by the exposure to inhaled irritants such as dust or smoke particles.
Researchers have found that these irritants and smoke can result in the accumulation of inflammatory cells such as CD8+ T-lymphocytes, neutrophils, macrophages, and B-cells (Fishman, et al., 2008). Upon stimulation, these cells result in an inflammatory reaction that causes the release of inflammatory mediators (Barnes, et al., 2009) as, for example, tumor necrosis factor alpha (TNF-α), matrix-metalloproteinases (MMP-6, MMP-9), interferon gamma (IFN-γ), interleukins (IL-1, IL-6, IL-8), C-reactive protein (CRP), and fibrinogen. These inflammatory mediators can prolong the inflammatory process resulting in the damage to the tissues along with a number of other systemic effects. This chronic inflammation also affects the structure of the lungs that is responsible for further limitation in airflow.
If we consider the structural changes, we can find that there is narrowing of airways as a result of inflammation. There are three important factors that are involved in this phenomenon;
- accumulation of scar tissue from injury or harm to the airways,
- peribronchial fibrosis, and
- over-multiplication of the epithelial cells present in the lining of the airways.
During the diseased condition, parenchymal destruction is related to the loss of lung tissue elasticity, which is due to the damage to the supporting structures of the alveoli resulting in emphysema. This shows that small airways fail to work during the process of exhalation resulting in stoppage of airflow and trapping of the air in the lungs, thereby decreasing the lung capacity.
Signs and Symptoms
Initially, COPD may show no signs and symptoms or slight level of symptoms, but with the passage of time the disease can get worse and symptoms may become severe. Some people don’t know that they are having COPD. Commonly assessed signs and symptoms of COPD are as follows:
- Ongoing form of cough with mucus or without mucus. It is also known as “smoker’s cough”,
- Several respiratory problems and shortness of breath especially with some physical activity. This problem shows progress of the disease towards severity,
- Fatigue,
- Wheezing, i.e. a kind of squeaky or whistling sound upon breathing, and
- Chest tightness.
Sometimes, patients of COPD may also have colds or the flu (influenza). These symptoms are not necessarily present in every patient of COPD. Some symptoms of COPD are similar to other diseases, and the physician can rule out these conditions after proper testing or medical checkup.
Severity of symptoms depends on the level of damage to the lung or lungs. In the presence of smoking, damage to the lungs is faster than in the absence of smoking, and symptoms can be more severe. Severe cases of COPD can also result in other symptoms such as inflammation in ankles, legs, or feet; loss of weight, and lower muscle endurance. Some severe symptoms may also require treatment in hospitals. Emergency care is necessary, if;
- There is extreme difficulty in breathing,
- The color of lips or fingernails is changed into blue or gray, which is the sign of low oxygen level in the blood,
- The patient is not mentally alert, or
- There is very fast heartbeat.
Exams and Tests of COPD
Lung function test known as spirometry is considered as the best test for COPD. This test involves blowing out with maximum efficiency into a small machine that checks the lung capacity. Results of the test can be checked instantaneously.
Stethoscope can also be used to listen to the proper function of lungs. However, this is not a good test as the lungs may sound normal but the person still has COPD. Similarly, X-rays and CT scans, which are imaging tests of the lungs, can also be used, but they are also not successful in every case of COPD. Sometimes, the measurement of oxygen and carbon dioxide in the blood of the patient can also be done. This blood test is known as arterial blood gas.
Prognosis of COPD
COPD is a chronic type of illness that can last for longer times. According to the National Heart Lung and Blood Institute (NHLBI), over 12 million American adults have been reported to have the problem of COPD and nearly the same numbers of people have COPD but are unaware of the problem (Doney, et al., 2014). COPD is fourth leading cause of mortality in the U.S.
Exact prediction of life after the onset of COPD is not present in medical science. However, it can decrease the lifespan of the patients. In this regard, overall health and the presence of other diseases such as diabetes and heart disease also play an important role.
Researchers have worked on a number of ways to measure life expectancy after the start of disease. “Staging”, i.e. determination of the severity of the problem, is considered to be one of the most commonly used methods. In this regard, The “Global Initiative for Chronic Obstructive Lung Disease” (GOLD) has provided a measurement system known as the GOLD system. In this system, forced expiratory volume (FEV1) is used to determine the amount of air that can be forcefully exhaled by the person, and severity of COPD is determined on the basis of this factor and divided into four stages;
- Stage 1 shows mild type of COPD with FEV1 about 80% or more of normal,
- Stage 2 shows moderate COPD with FEV1 in the range of 50%-80% of normal,
- Stage 3 shows severe emphysema with FEV1 in the range of 30%-50% of normal,
- Stage 4 shows very severe COPD with lower FEV1 as compared to Stage 3.
Usually, prognosis worsens with increase in the stage of COPD.
Another method of measuring the severity of COPD is BODE index that is not dependent only on FEV1. In this index, the word “BODE” has been developed from “b” of “body mass”, “o” in “airflow obstruction”, “d” in “dyspnea”, and “e” in “exercise capacity”. In this way, this method considers an overall picture of the affect of COPD on life.
- Body mass index helps in the determination of being overweight, obese, or too thin. People who are too thin are considered to have worse prognosis,
- Airflow obstruction can be considered as FEV1 that is also found in GOLD system,
- Dyspnea refers to difficult or troubled breathing. Research has shown that people with troubled breathing have least chance of survival as compared to those people who have a better ability to breathe,
- Exercise capacity refers to the ability to exercise. This is usually measured with the help of a test known as the “six minute walk test”.
Prevention and Treatment of COPD
Prevention is among the best strategies to get rid of problems of the body. People can do some things to prevent worsening of the problem as, for example, avoidance from very cold air, avoidance of smoking of any person in the home, and reduction in air pollution by getting rid of any kind of smoke producers such as fireplace, and other irritants. Healthy eating habits such as the inclusion of fish, fruits and vegetables in the food can also help in living a better life. Eating small frequent meals can help in increasing the food intake in case of eating problems. Learning the methods of improving the breathing with exercises such as pursed lip breathing can also help the patients in proper breathing.
Presently, the disease is without any proper treatment, but many things can be done to relieve the different symptoms of the disease and to reduce the chances of worsening of the condition. One of the first steps in treatment strategy is to quit smoking. Some medicines can also be used to get relief from the problems of COPD (Behera, 2010) as, for example,
- Bronchodilators can be used to open up the airways. Bronchodilators are usually given with inhalers,
- Steroids through inhalation or oral route can also be used to decrease the lung inflammation,
- Anti-inflammatory drugs can also be used to decrease swelling in the airways.
Antibiotics are also used during severe conditions of COPD as infections can worsen the condition. Although, pulmonary rehabilitation has nothing to do with the treatment of COPD, it can help in breathing in a different way.
Surgery can also be used for the treatment of COPD but it can help only a few patients. Surgery may include:
- Removal of diseased parts of the lung that can help in better working of other normal parts of the lungs of patients with emphysema,
- Transplantation of lungs in severe cases of the disease.
Terminology
Alpha-1 antitrypsin: It is a protease inhibitor that protects tissues from enzymes of inflammatory cells.
B-cells: These are types of lymphocytes that are involved in production of antibodies against antigens.
C-reactive protein (CRP): It is the protein whose level rises in response to inflammation.
CD8+ T-lymphocytes: These are T-cells that are involved in the killing of cancer cells, cells that are infected with viruses, or other kind of damaged cells.
Emphysema: It refers to the abnormal condition of the lungs that is characterized by reduced respiratory function. It is usually associated with smoking, old age, or chronic bronchitis.
Fibrinogen: Fibrinogen is a protein that is involved in the formation of blood clots.
Fibrosis: It refers to the development of excessive fibrous connective tissue in an organ.
Interferon gamma (IFN-γ): It is the protein that is related to the adaptive and innate immunity against viruses.
Interleukins: These are the proteins, and functions in most of the immune system.
Macrophages: These are the type of white blood cells that are involved in the process of phagocytosis of foreign substance or cancer cells.
Matrix-metalloproteinases: These are the proteins that are involved in degradation of all kinds of extracellular matrix proteins.
Neutrophils: These are the types of white blood cells that are recruited to the site of injury.
Tumor necrosis factor alpha (TNF-α): These are the proteins that are involved in systemic inflammation. They also regulate immune cells.
References
Barnes, P. J., Drazen, J. M., Rennard, S. I. and Thomson, N. C. 2009. Asthma and COPD: Basic Mechanisms and Clinical Management, Elsevier Science.
Behera, D. 2010. Textbook of Pulmonary Medicine, Jaypee Brothers Medical.
Doney, B., Hnizdo, E., Dillon, C. F., Paulose-Ram, R., Tilert, T., Wolz, M. and Beeckman-Wagner, L.-A. 2014. Prevalence of Airflow Obstruction in US Adults Aged 40-79 Years: NHANES Data 1988-1994 and 2007-2010. COPD: Journal of Chronic Obstructive Pulmonary Disease.
Fishman, A., Elias, J., Fishman, J., Grippi, M. and Pack, A. 2008. Fishman's Pulmonary Diseases and Disorders, Fourth Edition, Mcgraw-hill.
Hillerdal, G. and Mindus, S. 2011. One year follow-up of intrabronchial lung volume reduction in alpha-1-antitrypsin deficiency and severe emphysema. European Respiratory Journal, 38, p3538.
Lynn, J., Harrold, J. and Schuster, J. L. 2011. Handbook for Mortals: Guidance for People Facing Serious Illness, OUP USA.
