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Chronic Obstructive Pulmonary Disease
Emphysema and Chronic Bronchitis
Chronic obstructive pulmonary disease (COPD) is a progressive and debilitating lung disease. The disease is characterized by irreversible airflow limitation in the lungs. The umbrella of COPD encompasses the following conditions:
* Emphysema, in which the alveoli in the lungs, the tiny sacs where oxygen transfer takes place, are destroyed and enlarged
* Chronic bronchitis, or the permanent inflammation of airways, accompanied by a chronic cough
COPD exacts a tremendous toll on society. It affects more than 16 million people in the United States, and by 2020 it is expected to rise from the sixth- to the third-most-common cause of death in the world (Kasper DL et al 2005). Unfortunately, there is no single safe and effective treatment. However, because COPD is an inflammatory disease in which sufferers are subjected to high levels of oxidative stress, high doses of antioxidants and natural anti-inflammatories may be able to slow the disease's progression and reduce the amount of prescription medication needed.
Inflammation and Airway Restriction
The major cause of COPD in the United States is cigarette smoking, although it has also been linked to other factors, such as hyperresponsive airways, respiratory infections, and exposure to dust and environmental pollutants. The longer and more heavily people smoke, the more likely they are to develop COPD.
COPD is usually a progressive disease that develops slowly, often over the course of decades. In a typical case, a cigarette smoker would experience declining lung function for many years before being diagnosed with COPD and receiving therapy. During those years, while the disease is developing, the lungs are undergoing several changes characteristic of the disease.
The bulk of lung tissue is composed of alveoli, or tiny sacs, where the exchange of oxygen and carbon dioxide takes place. One of the primary factors in COPD is emphysema, which occurs when alveoli enlarge and cluster. This process destroys the very sensitive areas where gases are exchanged across thin walls. Emphysema occurs in stages. First, chronic exposure to an irritant, such as cigarette smoke, causes inflammatory cells (such as macrophages and neutrophils) to gather in the airspaces of the lung. These inflammatory cells release chemicals that damage the extracellular matrix of the lung, that is, the proteins that are responsible for providing structure to the lungs. Finally, the ability of the lung to repair the extracellular matrix is compromised, resulting in the coalescence of alveoli into larger, less efficient air chambers.
People with emphysema also suffer from airway obstruction, especially in airways less than 2 mm in diameter. A number of changes occur in these airways that aggravate the disease, including hypertrophy of smooth muscle cells, the formation of scar tissue in the airway walls (fibrosis), and the infiltration of inflammatory cells.
Underlying all this damage is an inflammatory response mounted by the immune system. In a typical case, cigarette smoke in the lungs would come into contact with macrophages (immune system cells) that normally patrol the airspace. In response to the toxins in the smoke, the macrophages release inflammatory chemicals and begin to recruit more immune-system cells, which in turn release more inflammatory chemicals, as well as enzymes that degrade the extracellular matrix.
These changes in the lung are detectable but incremental. Symptoms appear gradually and may actually have been present for many years before a patient seeks medical treatment. Coughing, sputum production, and breathlessness are the characteristic symptoms associated with COPD. Early in the disease, the patient's physical examination may even be normal. Later in the disease, however, patients sometimes develop the classic “barrel chest” associated with COPD. It occurs because residual air is trapped in the lungs, leading to their hyperinflation. In addition, the increased effort required to exhale can produce wheezing, while pursed lips or grunting respirations may signal the patient's efforts to keep the airways open by increasing pressure at the beginning of expiration (Lim TK 1996).
COPD is a variable condition, with some patients having more symptoms of emphysema, such as breathlessness and “air hunger,” while others manifest more symptoms of chronic bronchitis or asthma, such as wheezing and air trapping (Kasper DL et al 2005). The manifestations of COPD are not limited to the lungs. COPD also puts patients at increased risk of atherosclerosis and osteoporosis. Poor lung function and poor nutrition may cause muscle weakness, abnormalities in fluid and electrolyte balance, and depression.
Now, people with COPD (including emphysema), their bodies have learned to compensate for lack of oxygen and an increase of CO2 (carbon dioxide). Giving oxygen in the wrong amounts, whether by nasal cannula, mask, or exercise, wipes out the drive to breathe, making it harder for the patient to actually get good O2 saturations.