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Chronic Obstructive Pulmonary Disease (COPD) / Lung Emphysema - Part 1


Chronic obstructive pulmonary disease, or COPD, is known as a group of lung diseases that cause air flow limitations and problems related to breathing. The progressive disease affects roughly 15 million adults and is the fourth leading cause of death in the United States. While the leading cause of COPD is smoking, approximately 20% of adults with COPD have never smoked. The two most common conditions of COPD are chronic bronchitis and emphysema. Diagnosis of the disease is crucial to starting treatment as soon as possible and can vary from patient to patient. An early diagnosis may prevent any further lung function loss and the symptoms can be successfully managed. Although there are different options for managing the symptoms and the treatment of COPD, there is currently no cure for the disease.

What are the causes of COPD?

The most common cause of COPD is smoking. Although roughly one in four patients diagnosed with COPD have no history of smoking. COPD can eventually limit routine and basic activities of the patients such as walking due to poor quality of air circulation. Typically, those who are over the age of 65 are at a higher risk for developing COPD.

Smoking causes roughly 90% of all COPD cases as tobacco smoke will irritate the airways, triggering inflammation that will cause the airways to narrow. The cilia can also become damaged, allowing for mucus and trapped particles to remain in the airways. When a cigarette is in use, it burns more than 7,000 chemicals that are harmful to a person. These chemicals ultimately weaken the lungs again infections, infecting the air sacs in the lungs. Secondhand smoke, air pollution, workplace exposures, and a genetic condition known as AAT deficiency are other known causes of COPD. AAT, or alpha-1 antitrypsin deficiency, is an inherited disorder that has the potential to lead to emphysema. Since alpha-1 antitrypsin is responsible for protecting the lungs, patients experiencing AAT deficiency do not produce enough of the enzyme. The lungs of the patient with COPD are likely to experience damage from exposure to irritating substances. Occupational and life exposures can increase the risk of developing COPD later in life.

What is the pathology of COPD?

COPD is a common and uncurable disease of the lungs that is progressive and associated with a chronic inflammatory response in airways and the lungs. Patients who are diagnosed with COPD experience less air flow entering and exiting the airways, leading to breathing complications. There are three types of mechanisms that result in limitations of the airways which includes a partial block of the lumen, thickening of the airway wall, and abnormalities of the tissues surrounding the airways. The two common conditions of COPD that are characterized by the previous mechanisms are that chronic bronchitis involves a partial block of the lumen and emphysema results in radial traction loss.

COPD will vary from person to person; however, most patients will experience both chronic bronchitis and emphysema while coping with COPD. With emphysema, the walls of the air sacs in the lungs become damaged. Lungs are typically elastic to allow the air sacs to inflate and deflate when breathing. As the air sacs lose elasticity, it becomes harder for the lungs to move air out of the body leading to breathing complications. Elastin, a protein that provides elasticity to the lungs, is lost in emphysema, causing permanent destruction of elastic fibers and hyperventilation. The exact cause of emphysema is not fully understood, but various mechanisms such as protease-antiprotease imbalance, ROS activity, inflammation, and mechanical forces are believed to contribute. The pathophysiology of COPD involves the degradation of elastic fibers in lung tissue by specific enzymes, including MMP-2, -9, -12, neutrophil elastase, and cathepsins. This leads to fibrosis, as the tissue cannot regenerate the elastin matrix, and remodeling or regeneration of the elastin matrix rarely occurs [1]. Collagen remodeling results in fibrosis, and the inability of lung tissue to regenerate elastic fibers leads to progressive worsening of emphysema.

What are the symptoms of COPD?

COPD is known to present no or only mild symptoms at the beginning of the disease. Since the disease progresses, the symptoms will usually develop in severity over time. There are millions of patients living with COPD, but many are unaware that they have the disease. People tend to change their lifestyles to help improve breathing before seeking medical help. The common signs and symptoms of COPD consist of a constant and chronic cough, shortness of breath that worsens with daily activities, inability for deep breathing, wheezing, and excess sputum. As the symptoms gradually worsen over time, treatment can help to slow the progression. It is common for periods of time when symptoms suddenly worsen, which is known as a flare-up or exacerbation. The flare-ups are more common in the winter but can happen a few times a year. Examples of less common symptoms include weight loss, tiredness, chest pain, and coughing up blood tend to only occur in the advance stage of COPD.

Image of Chronic Obstructive Pulmonary Disease (COPD)
Image from Cleveland Clinic, describing COPD visually

But how is COPD diagnosed and what are treatment options? Find out in part 2, which will be published next week!




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