Chronic obstructive pulmonary disease (COPD) is a term referring to two lung diseases, chronic bronchitis and emphysema, that are characterized by obstruction to airflow that interferes with normal breathing. 

Both chronic bronchitis and emphysema frequently co-exist, hence physicians prefer the term COPD.

COPD does NOT include other obstructive diseases such as asthma.

COPD is not well understood or recognized – most Americans have not heard of it, not even those who may be living with the condition.

The diagnostic process for COPD includes a thorough medical history as well as one or more of the following diagnostic procedures.

• Pulmonary Function Tests
• Oximetry
• Radiological Procedures
• Arterial Blood Gases
• Alpha-1-Antitrypsin Level

History and Examination
Patients with COPD usually are current or past smokers over the age of 40 with a history of shortness of breath upon physical exertion and chronic productive cough. The physical examination may show a barrel chest, decreased breath sounds, and wheezing. Signs of right-sided heart failure, such as edema, tender liver, and distended abdomen (caused by fluid accumulation in the abdomen; called ascites) may be noted as well. COPD is a diagnosis of history (in the case of chronic bronchitis), or a diagnosis of anatomy (in the case of emphysema). Clubbing of the fingers rarely occurs in COPD and warrants investigation for other causes.

Pulmonary Function Tests (PFTs)
Pulmonary function tests are the primary diagnostic tools for COPD, after the medical history and physical examination. These tests demonstrate characteristic abnormalities in lung function that, in the proper clinical context (i.e., medical history, physical examination, chest x-ray) confirm or support the diagnosis of COPD and give some idea of the degree of impairment and prognosis. Lung biopsy is rarely used to diagnose emphysema.

There are four components to pulmonary function testing:

• spirometry,
  
• postbronchodilator spirometry,
  
• lung volumes, and
• diffusion capacity.
  

• Spirometry. The most reliable way to determine reversible airway obstruction is with spirometry, a procedure that measures the amount of air entering and leaving the lungs. This simple test can be performed in most physicians' offices, with the patient sitting comfortably in front of the spirometry machine.Those most commonly used for interpretation are (1) forced expiratory volume after 1 second [FEV1], (2) forced vital capacity [FVC], and (3) forced expiratory flow at 25%-75% of maximal lung volume [FEF25-75]. They are expressed as percentages of what is predicted for normal lung function, depending on the variables of height, age, race, and sex. COPD produces characteristic results in this test. The amount of air exhaled (forced vital capacity, or FVC) is reduced, compared to a person with normal lung function. Futhermore, the amount of air exhaled during the initial 1 second (FEV1) is reduced and is reduced to a greater degree than the entire FVC. Therefore, the ratio of air exhaled after 1 second is low compared to the total amount of air exhaled. In healthy lungs, 70%-75% of all the air exhaled after maximum inhalation (FVC) is exhaled within the first second (FEV1), known as the FEV1/FVC ratio. In lungs with COPD, the FEV1/FVC ratio falls below 70%-75%.  The absolute value of the FEV1 is also reduced. The FEV1 can be reduced in another disease process, termed restrictive ventilatory defects. However, in restrictive ventilatory defects the FVC is reduced proportionally, preserving a normal FEV1/FVC ratio. The FEV1 is used to quantify the severity of obstruction with a FEV1 < 70% of what is predicted for age, height, weight and race considered mild; < 50% to 69%, moderate; < 35%-49%, severe; and < 35%, very severe. Sometimes the only abnormality is a reduction in the FEF25-75. Isolated reduction in the FEF25-75 is considered an early detector of very mild obstruction. It can also be a normal variant.     
• Postbronchodilator Spirometry. Spirometry is often repeated after giving the patient a bronchodilator, such as an inhaled beta-agonist. If the FEV1 (forced expiratory volume after 1 second) improves more than 12%, the obstruction may be reversible or partially reversible. This procedure provides some information on the potential responsiveness of the airways to medication. It is also useful for determining whether steroid treatment has been beneficial, a few weeks after initiating therapy.
• Peak expiratory flow rate (PEFR). PEFR can be compared with readings the patient obtains at home with a peak flow meter. A peak flow meter is a portable device that consists of a small tube with a gauge that measures the maximum force with which one blows air through the tube.
• Lung Volumes.  Lung volumes are measured in two ways, gas dilution or body plethysmography. The gas dilution method is performed after the patient inhales a gas, such as nitrogen or helium. The amount of volume in which the gas is distributed is used to calculate the volume of air the lungs can hold. Body plethysmography requires the patient to sit in an airtight chamber (usually transparent to prevent claustrophobia) and inhale and exhale into a tube. The pressure changes in the plethysmograph are used to calculate the volumes of air in the lungs. The most important measurements obtained are residual volume and total lung capacity (TLC). These measurements vary with age, height, weight, and race and are usually expressed as an absolute number and a percentage of what is predicted for a person with normal lung function. A high TLC demonstrates hyperinflation of the lungs, which is consistent with emphysema. Increased residual volume signifies air trapping. This demonstrates an obstruction to exhalation.
• Diffusion Capacity. Diffusion capacity is a measurement of gases transfered from the alveoli to the capillary. The patient inhales a very small amount (very safe) of carbon monoxide. How much of it is taken into the blood is measured. A reduced diffusion capacity is consistent with emphysema but is seen in a many other lung diseases as well.
• Oximetry.This noninvasive method determines the oxygenation of the blood (O2 sat; normal is greater than 90%) by measuring the amount of light transmitted through an area of skin. The device must be able to read pulsatile flow, so it must pick up a pulse to be accurate. Oximetry is not as accurate as the measurement of arterial blood gases. It is commonly used during exercise and sleep. Exercise oximetry can determine if a patient's oxygen decreases during activity. If so, oxygen therapy with activity may be beneficial. Overnight oximetry is done to see if oxygen concentrations decrease during sleep.
• Radiology. Chest x-ray is an imprecise method of diagnosis of COPD. It is only consistently abnormal in severe cases and should be performed in the initial evaluation to exclude other lung diseases. Findings characteristic of COPD in chest x-ray are hyperinflated lungs with flattened diaphragm, hyperlucent lungs (chest film shows greater than normal film blackening from increased transmission of x-rays), and central pulmonary artery enlargement. Bullae, areas of destroyed lung tissue that create large dilated air sacs, may be seen as well.
• CT scan. A CT scan may be used to more accurately diagnose emphysema. This is usually not necessary, however, and abnormal lung anatomy is not always detected.
• Arterial Blood Gases. Arterial blood gases are measured using blood drawn from an artery, usually in the wrist. Blood is usually drawn from a vein, but venous blood is inaccurate for these measurements. Drawing blood from an artery, unfortunately, causes more discomfort.Arterial blood gases are measured to determine the amount of oxygen dissolved in the blood (pO2), the percentage of hemoglobin saturated with oxygen (O2 sat), the amount of carbon dioxide dissolved in the blood (pCO2), and the amount of acid in the blood pH. The oxygen measure may be used to determine whether a patient needs oxygen therapy. The carbon dioxide measure gives some idea of lung function and is especially important to know when starting oxygen therapy (see Oxygen).
• Alpha-1-Antitrypsin Level. A person suspected of having a genetic deficiency of this enzyme will undergo this test. Alpha-1-antitrypsin deficiencies can also cause liver disease in children, and the level may be measured for that as well. If the level is low, a genetic probe may be used to determine the cause.

Treatment

Treatment for COPD should be PD is based on the patient's general medical condition and severity of the disease. Options usually include a combination of the following treatments. Proper treatment of COPD can result in improvements in exercise capacity, activity levels, quality of life, less hospitalization, and longer survival.

Smoking Cessation

The most important and effective treatment for COPD is smoking cessation.  The benefits of quitting smoking apply regardless of age, amount smoked or severity of COPD. Quitting smoking also reduces the risk of sudden cardiac death, heart attacks, strokes and lung cancer.

Medications

1. Short-acting bronchodilators, both beta agonists and anticholinergics, are the mainstay of therapy for COPD.
2. Long-acting bronchodilators are indicated for moderate to severe COPD. Currently two beta agonists are available. A long-acting anticholinergic is under consideration for approval by the U.S. Food and Drug Administration.
3. Inhaled corticosteroids are recommended for patients with moderate to severe COPD with frequent exacerbations (incidents which worsen symptoms).
4. Systemic corticosteroids (IV or pills) are beneficial for treatment of severe exacerbations.
5. Antibiotics may be beneficial for treatment of exacerbations.
6. Theophylline in low doses may reduce frequency of exacerbations in patients who tolerate it (it has many side effects).

Home oxygen therapy

Supplemental oxygen is prescribed to correct hypoxemia (low blood oxygen) to improve the physical and mental functioning of patients. Several studies have shown greater long-term survival in patients with severe COPD who received oxygen therapy.

Pulmonary rehabilitation

For those who have difficulty completing daily tasks, pulmonary rehabilitation may be very beneficial. This type of treatment can improve exercise capacity, reduce the hospitalization rate and improve overall quality of life for patients.

Surgery

Lung transplants are sometimes performed in severe cases of COPD.

Another option is lung volume reduction surgery (LVRS). In LVRS the surgeon removes small wedges of damaged tissue, usually 20 to 30 percent of each lung. Removing some damaged air sacs reduces the size of the lungs. As a result, the diaphragm contracts and relaxes more effectively and efficiently, and air exchange improves.

Results of a large clinical trial, called the National Emphysema Treatment Trial  showed that LVRS can improve the lung function of many people with emphysema. The findings of the five-year trial were published in the May 22, 2003, edition of the New England Journal of Medicine.

The success of LVRS varied widely in the study:

• In people whose emphysema occurred primarily in the upper lobes of their lungs and whose exercise capacity was still low after they had undergone several weeks of pulmonary rehabilitation, survival rates were longer and lung function was better after they underwent LVRS compared with people with similar preoperative findings who did not have the surgery.
• However, for people who did not have emphysema in the upper lobes of their lungs and who had a greater exercise capacity after pulmonary rehabilitation, the surgery lowered survival rates and did not result in higher lung function.