Chronic obstructive pulmonary disease
CHRONIC OBSTRUCTIVE PULMONARY DISEASE
CHRONIC OBSTRUCTIVE PULMONARY DISEASE DEFINITION
Chronic obstructive pulmonary disease (COPD) is a chronic inflammatory lung disease that causes obstructed airflow from the lungs. Symptoms include breathing difficulty, cough, sputum production and wheezing. It’s caused by long-term exposure to irritating gases or particulate matter, most often from cigarette smoke. People with COPD are at increased risk of developing heart disease, lung cancer and a variety of other conditions.
Emphysema and chronic bronchitis are the two most common conditions that contribute to COPD. Chronic bronchitis is inflammation of the lining of the bronchial tubes, which carry air to and from the air sacs (alveoli) of the lungs. It is characterized by daily cough and sputum production. Emphysema is a condition in which the air sacs (alveoli) at the end of the smallest air passages (bronchioles) of the lungs are destroyed as a result of damaging exposure.
COPD is treatable. With proper management, most people with COPD can achieve good symptom control and quality of life, as well as reduced risk of other associated conditions.
CHRONIC OBSTRUCTIVE PULMONARY DISEASE CAUSES
COPD is most often caused bysmoking. Most people with COPDare long-term smokers, and research shows that smokingcigarettes increases the risk of getting COPD:
- Some studies show that up to half of long-term smokers older than age 60 get COPD.
- Smoking both tobacco andmarijuana increases the risk of COPD more than smoking either one.
CHRONIC OBSTRUCTIVE PULMONARY DISEASE PATHOPHYSIOLOGY
Pathologic changes in chronic obstructive pulmonary disease (COPD) occur in the large (central) airways, the small (peripheral) bronchioles, and the lung parenchyma. Most cases of COPD are the result of exposure to noxious stimuli, most often cigarette smoke. The normal inflammatory response is amplified in persons prone to COPD development. The pathogenic mechanisms are not clear but are most likely diverse. Increased numbers of activated polymorphonuclear leukocytes and macrophages release elastases in a manner that cannot be counteracted effectively by antiproteases, resulting in lung destruction.
The primary offender has been found to be human leukocyte elastase, with synergistic roles suggested for proteinase-3 and macrophage-derived matrix metalloproteinases (MMPs), cysteine proteinases, and a plasminogen activator. Additionally, increased oxidative stress caused by free radicals in cigarette smoke, the oxidants released by phagocytes, and polymorphonuclear leukocytes all may lead to apoptosis or necrosis of exposed cells. Accelerated aging and autoimmune mechanisms have also been proposed as having roles in the pathogenesis of COPD.
Cigarette smoke causes neutrophil influx, which is required for the secretion of MMPs; this suggests, therefore, that neutrophils and macrophages are required for the development of emphysema.
Studies have also shown that in addition to macrophages, T lymphocytes, particularly CD8+, play an important role in the pathogenesis of smoking-induced airflow limitation.
To support the inflammation hypothesis further, a stepwise increase in alveolar inflammation has been found in surgical specimens from patients without COPD versus patients with mild or severe emphysema. Indeed, mounting evidence supports the concept that dysregulation of apoptosis and defective clearance of apoptotic cells by macrophages play a prominent role in airway inflammation, particularly in emphysema. Azithromycin (Zithromax) has been shown to improve this macrophage clearance function, providing a possible future treatment modality.
In patients with stable COPD without known cardiovascular disease, there is a high prevalence of microalbuminuria, which is associated with hypoxemia independent of other risk factors.
Mucous gland hyperplasia (as seen in the images below) is the histologic hallmark of chronic bronchitis. Airway structural changes include atrophy, focal squamous metaplasia, ciliary abnormalities, variable amounts of airway smooth muscle hyperplasia, inflammation, and bronchial wall thickening.
CHRONIC OBSTRUCTIVE PULMONARY DISEASE SYMPTOMS
Symptoms of COPD often don’t appear until significant lung damage has occurred, and they usually worsen over time, particularly if smoking exposure continues. For chronic bronchitis, the main symptom is a daily cough and sputum production at least three months a year for two consecutive years.
Other signs and symptoms of COPD include:
- Shortness of breath, especially during physical activities
- Chest tightness
- Having to clear your throat first thing in the morning, due to excess mucus in your lungs
- A chronic cough that produces sputum that may be clear, white, yellow or greenish
- Blueness of the lips or fingernail beds (cyanosis)
- Frequent respiratory infections
- Lack of energy
- Unintended weight loss (in later stages)
People with COPD are also likely to experience episodes called exacerbations, during which their symptoms become worse than usual day-to-day variation and persist for at least several days.
CHRONIC OBSTRUCTIVE PULMONARY DISEASE DIAGNOSIS
Chronic obstructive pulmonary disease (COPD) is usually diagnosed after a consultation with your GP, as well as breathing tests.
If you are concerned about the health of your lungs and have symptoms that could be COPD, see your GP as soon as you can.
Being diagnosed early means you will receive appropriate treatment, advice and help to stop or slow the progression of COPD.
At a consultation, your doctor will ask about your symptoms, how long you have had them, and whether you smoke, or used to smoke. They will examine you and listen to your chest using a stethoscope. You may also be weighed and measured to calculate your body mass index (BMI).
CHRONIC OBSTRUCTIVE PULMONARY DISEASE TREATMENT
A diagnosis of COPD is not the end of the world. Most people have mild forms of the disease for which little therapy is needed other than smoking cessation. Even for more advanced stages of disease, effective therapy is available that can control symptoms, reduce your risk of complications and exacerbations, and improve your ability to lead an active life.
The most essential step in any treatment plan for COPD is to stop all smoking. It’s the only way to keep COPD from getting worse — which can eventually reduce your ability to breathe. But quitting smoking isn’t easy. And this task may seem particularly daunting if you’ve tried to quit and have been unsuccessful.
Talk to your doctor about nicotine replacement products and medications that might help, as well as how to handle relapses. It’s also a good idea to avoid secondhand smoke exposure whenever possible.
Doctors use several kinds of medications to treat the symptoms and complications of COPD. You may take some medications on a regular basis and others as needed.
These medications — which usually come in an inhaler — relax the muscles around your airways. This can help relieve coughing and shortness of breath and make breathing easier. Depending on the severity of your disease, you may need a short-acting bronchodilator before activities, a long-acting bronchodilator that you use every day, or both.
Short-acting bronchodilators include albuterol (ProAir HFA, Ventolin HFA, others), levalbuterol (Xopenex), and ipratropium (Atrovent). The long-acting bronchodilators include tiotropium (Spiriva), salmeterol (Serevent), formoterol (Foradil, Perforomist), arformoterol (Brovana), indacaterol (Arcapta) and aclidinium (Tudorza).
Inhaled corticosteroid medications can reduce airway inflammation and help prevent exacerbations. Side effects may include bruising, oral infections and hoarseness. These medications are useful for people with frequent exacerbations of COPD. Fluticasone (Flovent) and budesonide (Pulmicort) are examples of inhaled steroids.
Some medications combine bronchodilators and inhaled steroids. Salmeterol and fluticasone (Advair) and formoterol and budesonide (Symbicort) are examples of combination inhalers.
For people who have a moderate or severe acute exacerbation, short courses (for example, 5 days) of oral corticosteroids prevent further worsening of COPD. However, long-term use of these medications can have serious side effects, such as weight gain, diabetes, osteoporosis, cataracts and an increased risk of infection as well as increased mortality associated with COPD.
A new type of medication approved for people with severe COPD and symptoms of chronic bronchitis is roflumilast (Daliresp), a phosphodiesterase-4 inhibitor. This drug decreases airway inflammation and relaxes the airways. Common side effects include diarrhea and weight loss.
This very inexpensive medication helps improve breathing and prevents exacerbations. Side effects may include nausea, headache, fast heartbeat and tremor. Side effects are dose related, and low doses are recommended.
Respiratory infections, such as acute bronchitis, pneumonia and influenza, can aggravate COPD symptoms. Antibiotics help treat acute exacerbations, but are not generally recommended for prevention. However, a recent study shows that the antibiotic azithromycin prevents exacerbations, but it isn’t clear whether this is due to its antibiotic effect or its anti-inflammatory properties.
Doctors often use these additional therapies for people with moderate or severe COPD:
- Oxygen therapy. If there isn’t enough oxygen in your blood, you may need supplemental oxygen. There are several devices to deliver oxygen to your lungs, including lightweight, portable units that you can take with you to run errands and get around town. Some people with COPD use oxygen only during activities or while sleeping. Others use oxygen all the time. Oxygen therapy can improve quality of life and is the only COPD therapy proven to extend life. Talk to your doctor about your needs and options.
- Pulmonary rehabilitation program. These programs typically combine education, exercise training, nutrition advice and counseling. You’ll work with a variety of specialists, who can tailor your rehabilitation program to meet your needs. Pulmonary rehabilitation may shorten hospitalizations, increase your ability to participate in everyday activities and improve your quality of life. Talk to your doctor about referral to a program.
Even with ongoing treatment, you may experience times when symptoms become worse for days or weeks. This is called an acute exacerbation, and it may lead to lung failure if you don’t receive prompt treatment.
Exacerbations may be caused by a respiratory infection, air pollution or other triggers of inflammation. Whatever the cause, it’s important to seek prompt medical help if you notice a sustained increase in coughing, a change in your mucus or if you have a harder time breathing.
When exacerbations occur, you may need additional medications (such as antibiotics or steroids or both), supplemental oxygen or treatment in the hospital. Once symptoms improve, your doctor will talk with you about measures to prevent future exacerbations, such as quitting smoking, taking inhaled steroids, long-acting bronchodilators or other medications, getting your annual flu vaccine, and avoiding air pollution whenever possible.
Surgery is an option for some people with some forms of severe emphysema who aren’t helped sufficiently by medications alone:
- Lung volume reduction surgery. In this surgery, your surgeon removes small wedges of damaged lung tissue from the upper lungs. This creates extra space in your chest cavity so that the remaining healthier lung tissue can expand and the diaphragm can work more efficiently. In some people, this surgery can improve quality of life and prolong survival.
- Lung transplant. Lung transplantation may be an option for certain people who meet specific criteria. Transplantation can improve your ability to breathe and to be active, but it’s a major operation that has significant risks, such as organ rejection, and it obligates you to take lifelong immune-suppressing medications.