Chronic Obstructive Pulmonary Disease(COPD)

What is COPD ?

Chronic obstructive pulmonary disease, or COPD, is a long-lasting obstruction of the airways that occurs with chronic bronchitis, emphysema, or both. This obstruction of airflow is progressive in that it happens over time.

Chronic bronchitis is defined as a chronic (ongoing, long-term) cough not caused by another condition that produces sputum (mucus) for 3 or more months during each of the 2 consecutive years.

In chronic bronchitis, the mucous glands in the lungs become larger. The airways become inflamed, and the bronchial walls thicken. These changes and the loss of supporting alveolar (air space) attachments limit airflow by allowing the airway walls to deform and narrow the airway lumen (the inside of the airway tube).

Emphysema is an abnormal, permanent enlargement of the air spaces (alveoli) located at the end of the breathing passages of the lungs (terminal bronchioles). Emphysema also destroys the walls of these air spaces.

There are 3 types of emphysema: centriacinar emphysema, panacinar emphysema, and distal acinar emphysema or paraseptal emphysema.

Causes :

• Cigarette smoking or exposure to tobacco smoke
• Air pollution
• Airway hyperresponsiveness
• Alpha1-antitrypsin (AAT) deficiency

Symptoms :

Most people with COPD have smoked at least 10-20 cigarettes per day for 20 or more years before experiencing any symptoms. Thus, COPD is typically not diagnosed until the fifth decade of life (in people aged 40-49 years).

[Enlarged view of lung tissue showing the difference between healthy lung and COPD]

Common signs and symptoms of COPD are as follows:

• A productive cough or an acute
  
  
• Breathlessness or being short of breath (called dyspnea) is the most significantsymptom, but it does not usually occur until the sixth decade of life (in people aged 50-59 years).
  
  
• Wheezing is a musical, whistling, or hissing sound with breathing. Some people may wheeze, especially during exertion and when their condition worsens.

The following may occur as COPD worsens:

• Intervals between acute periods of worsening of dyspnea (exacerbations) become shorter.
  
  
• Cyanosis (discoloration of the skin) and failure of the right side of the heart may occur.
  
  
• Anorexia and weight loss often develop and suggest a worse prognosis.

The American Thoracic Society (ATS) recommends the following clinical staging of COPD severity according to lung function:

• Stage I is FEV₁ of equal or more than 50% of the predicted value.
  
  
• Stage II is FEV₁ of 35-49% of the predicted value.
  
  
• Stage III is FEV₁ of less than 35% of the predicted value.

Diagnosis :

To figure out if you have COPD, your doctor may do one or many of these diagnostic tests:

Ask questions about your health history

Your doctor may ask:

• What is your smoking history?
• Do you suffer from shortness of breath?
• What makes your shortness of breath worse?
• Do you cough?
• Do you bring up sputum (phlegm, mucus), and if so, what does it look like?
• What is your family history of lung disease?

Spirometry and other lung function testing

Spirometry is a common and effective diagnostic test that can easily be done in your doctor's office or at a nearby hospital or clinic. You will be asked to blow, as long and hard as you can, into a small tube attached to a machine. The machine measures how long it takes to blow out all the air from your lungs. The more blocked your airways, the longer it takes to blow the air out. Spirometry is the most reliable way to test your lungs for COPD.

Chest x-ray

The x-ray will help the doctor see if there is damage to your lungs.

Blood test

This test measures the amount of oxygen and carbon dioxide in your blood.

Medical Treatment :

The 3 major goals of the comprehensive treatment of COPD are as follows:

• Lessen airflow limitation
  
  
• Prevent and treat secondary medical complications (eg, hypoxemia, infection)
  
  
• Decrease respiratory symptoms and improve quality of life

You may need to be hospitalized if you develop severe respiratory dysfunction, if your disease progresses, or if you have other serious respiratory diseases (eg, pneumonia, acute bronchitis). The purpose of hospitalization is to treat symptoms and to prevent further deterioration.

You may be admitted to an intensive care unit (ICU) if you require invasive or noninvasivemechanical ventilation or if you have the following symptoms:

• Confusion
  
  
• Lethargy
  
  
• Respiratory muscle fatigue
  
  
• Worsening hypoxemia (not enough oxygen in the blood)
  
  
• Respiratory acidosis (retention of carbon dioxide in the blood)

Medication :

Smoking cessation using nicotine replacement therapies

The supervised use of medications is an important adjunct to smoking cessation programs.

Nicotine is the ingredient in cigarettes primarily responsible for the addiction. Withdrawal from nicotine may cause you to have unpleasant side effects, such as anxiety, irritability, difficulty concentrating, anger, fatigue, drowsiness, depression, and sleep disruption. These effects usually occur during the first several weeks after you stop smoking.

Nicotine replacement therapies reduce thesewithdrawal symptoms. If you require your first cigarette within 30 minutes of waking up, you are most likely highly addicted and would benefit from nicotine replacement therapy.

Several nicotine replacement therapies are available.

Nicotine polacrilex is a chewing gum. Chewing pieces come in 2 strengths (ie, 2 mg, 4 mg). If you smoke 1 pack per day, you should use 4-mg pieces. If you smoke less than 1 pack per day, you should use 2-mg pieces. You should chew hourly and also chew when needed for any initial cravings within the first 2 weeks. You should gradually reduce the amount chewed over the next 3 months.

Transdermal nicotine patches are also available. Patches are well tolerated. The most common side effect is slight skin irritation where the patch is placed. Nicotine replacement therapy patches are sold under the following trade names: Nicoderm, Nicotrol, and Habitrol. Each product has a scheduled decrease in nicotine over 6-10 weeks.

The use of the antidepressant bupropion (Zyban) is effective. It is a nonnicotine aid to smoking cessation. Bupropion may also be effective for those people who have not been able to quit smoking with nicotine replacement therapies.

Inhaled steroids

Some people with COPD who respond well to oral corticosteroids can be maintained on long-term inhaled steroids.

The use of these drugs is widespread, despite little evidence of efficacy in the treatment of COPD. Inhaled corticosteroids do not slow the decline in lung function. They do, however, decrease the frequency of exacerbations and improve disease-specific and health-related quality of life issues for some people with COPD.

Inhaled corticosteroids have fewer side effects than oral steroids, but they are less effective than oral steroids, even at high doses.

Beta2 Agonists - Bronchodilators

Inhaled beta2-agonist bronchodilators relax and open the breathing passages. They work rapidly, typically within minutes.

Beta2 agonists are primarily used to relieve symptoms of COPD. Inhaled beta2 agonists are the treatment of choice for acute exacerbations of COPD.

Two long-acting beta2 agonists (ie, formoterol, salmeterol) are available. They may be useful if you frequently use short-acting beta2-bronchodilators or if you experience symptoms at night.

Anticholinergic agents - Bronchodilators

Maintenance treatment with aerosolized anticholinergic agents (eg, ipratropiumbromide) may be more effective than beta2 agonists for people with COPD, particularly in relieving shortness of breath.

Ipratropium bromide opens the breathing passages and has minimal side effects.

It is administered by a metered-dose inhaler, at 2-4 puffs 4 times a day. Beta2 agonists can be added as needed.

Although it is slower to take effect (eg, 30-60 min) than inhaled beta2 agonists, ipratropium bromide lasts longer. Because of this, it is less suitable for use on an as-needed basis.

People undergoing exacerbations of COPD respond well to inhaled beta2-agonists and anticholinergic aerosols (eg, ipratropium bromide). Treatment usually begins with an inhaled beta2-agonist delivered via a spacer or a nebulizer, which creates a mist of the drug. Delivering the drug this way also reduces the side effects. Inhaled ipratropium bromide is also usually added.

Long-acting bronchodilators

Methylxanthines, such as theophylline, are a group of medications chemically related to caffeine. They work in COPD by opening the breathing passages. In addition, methylxanthines reduce inflammation, improve respiratory muscle function, and stimulate the brain respiratory center.

Adding theophylline to the combination of bronchodilators can be beneficial, although the response to theophylline may vary among people with COPD. Their use has decreased over the last decade because of the risks of unwanted side effects. Side effects include anxiety, tremors, insomnia, nausea, cardiac arrhythmia, and seizures.

Oral steroids

Corticosteroids are used for people who do not improve sufficiently after trying other drugs or who develop an exacerbation.

Oral steroids have been used successfully to treat acute exacerbations. They improve symptoms and lung function in this circumstance. Oral corticosteroids are generally not recommended for long-term use because of their potential side effects.

Antibiotics

In people with COPD, chronic infection of the lower airways is common. The goal ofantibiotic therapy is not to eliminate organisms but to treat acute exacerbations.

This therapy is most beneficial for people whose exacerbations are characterized by at least 2 of the following (ie, Winnipeg criteria): increased shortness of breath, increased sputum production, and increased sputum purulence.

First-line treatment choices include amoxicillin, cefaclor, or trimethoprim/sulfamethoxazole. Second-line treatment choices includeazithromycin, clarithromycin, and fluoroquinolones.

Mucolytic agents

Mucolytic agents not only reduce sputum viscosity (resistance to its flow) but also improve sputum clearance.

Oxygen therapy

COPD is commonly associated with worsening oxygenation of the blood (hypoxemia).

Surgery :

Over the past 50-75 years, various surgical approaches have been tried to improve symptoms and to restore lung function in people with emphysema. These are:

• Bullectomy
• Lung volume reduction surgery
• Lung transplantation

Prevention :

COPD cannot be cured but it can be prevented. To prevent COPD:

• Do not smoke, and, if you do smoke, quit.
  
  
• Eliminate your exposure to smoke by not allowing people to smoke in your home and by sitting in designated nonsmoking areas when out in public. You should also avoid wood smoke and cooking smoke.
  
  
• Limit air pollutants in your home.
  
  
• Try to avoid getting respiratory infections during cold and flu season. You should also frequently wash your hands becauseviruses can be passed through hand-to-mouth contact.
  
  
• Fight for clean air to prevent those cases of COPD due to air pollution.

COPD At A Glance :

• Chronic obstructive pulmonary disease (COPD) is characterized by chronic obstruction of airflow out of the lungs.
  
  
• COPD is comprised primarily of two related diseases - chronic bronchitis and emphysema.
  
  
• In chronic bronchitis there is inflammation and swelling of the lining of the airways that leads to their narrowing and obstruction.
  
  
• In emphysema there is permanent enlargement of the alveoli due to the destruction of the walls between alveoli.
  
  
• COPD causes poor gas exchange in the lungs leading to decreased oxygen levels in the blood, increased carbon dioxide levels, and shortness of breath.
  
  
• The major cause of COPD is smoking. Other less common causes include air pollution, repeated lung damage from infections, and inherited disease (alpha-1 antitrypsin deficiency).
  
  
• Treatment consists of cessation of smoking, medications to open the airways and decrease inflammation, prevention of lung infections, oxygen supplementation, and pulmonary rehabilitation.