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Chronic obstructive pulmonary disease

Description

An in-depth report on the causes, diagnosis, treatment, and prevention of COPD -- emphysema and/or chronic bronchitis.

Alternative Names

COPD; Alpha-1 antitrypsin deficiency; Bronchitis - chronic; Chronic bronchitis; Emphysema

Complications

In 2002, chronic obstructive lung disease was responsible for 120,000 deaths. COLD costs in the U.S. in 2004 reached $37.2 billion. It is the fourth leading cause of death in the U.S., and its death rates are increasing. Some evidence suggests that these death rates may be higher than current estimates, because COLD patients are at greater risk for life-threatening conditions, notably heart attack and pulmonary embolism.

Chronic obstructive lung disease is progressive; however, when patients stop smoking the disease often levels off.

• Outlook for Patients with Emphysema. If emphysema is detected before causing symptoms, there may be some chance of reversing it, although permanent changes in the alveoli usually occur, even in young smokers. Patients with the inherited form of early-onset emphysema are at risk for early death unless the disease is treated and its progression halted or slowed. Emphysema patients who experience severe involuntary weight loss (which indicates muscle wasting) have a poorer outlook, regardless of lung function.
• Outlook for Patients with Chronic Bronchitis. Chronic bronchitis does not cause as much lung damage as emphysema, although the airways become blocked by mucous plugs, and narrow due to inflammation. Thus poor air exchange causes reduced levels of oxygen, and high carbon dioxide levels. This state of poor gas exchange can lead to serious, life-threatening conditions that include severe breathing difficulty and heart failure.

Acute Exacerbations

Acute exacerbations are episodes that occur with both types of COLD. The airways suddenly become obstructed, and symptoms worsen. Such events are associated with inflammation in the airways and are triggered by infections about 80% of the time. They are not due to other complications of COLD, including pneumonia, heart failure, or a collapsed lung.

A new study found that 25% (one quarter) of people with COLD, who have an acute exacerbation with no known cause, actually suffer from pulmonary embolism (a blood clot in the lung). The risk for pulmonary embolism was higher in patients who had blood clot problems in the past and patients with cancer. The risk was also increased in patients whose carbon dioxide pressure in the alveoli was significantly reduced, compared to their usual levels.

Acute exacerbations include the following symptoms:

• Worsened shortness of breath. This is the most common and distressing acute symptom.
• Increased volume of sputum, which is also typically thicker and greenish in color.
• Wheezing.

Acute exacerbations occur, on average, between two and three times a year in patients with moderate to severe COLD. In about 80% of the cases, they are triggered by infections. Smokers have more episodes than nonsmokers do. Acute exacerbations resolve on their own, but they are still the most common cause of hospitalization in these patients. Patients with frequent acute exacerbations of COLD are at higher risk for disease deterioration, including reduced quality of life and increasing rates of hospitalizations. Furthermore, in patients who are hospitalized, the morality rates are 11%. Survivors of a first hospitalization have a 50% change of rehospitalization within 6 months.

A new study looked at physical activity levels of patients recovering from an acute exacerbation of COLD. The study found that such patients have very low levels of physical activity while in the hospital and after being discharged. The study found that patients with lower physical activity 1 month after discharge were more likely to be hospitalized within a year, for another episode of acute exacerbation. The researchers recommend adding appropriate amounts of exercise to the treatment of such patients.

Effect on Quality of Life and Mood

Nearly half of patients with COLD report that daily activities are limited. They have trouble walking up stairs or carrying even small packages. Breathing becomes hard work. More than half of patients with COLD often suffer from insomnia. Such impairment in quality of life can greatly impair mood. If patients with COLD become anxious or depressed, they may have a poorer outlook than those without these emotional problems. Even low-level depression can impair health. Of some concern was a 2003 study reporting a higher rate of suicidal thoughts in patients with COLD or asthma than in those with any other major chronic illness, including arthritis, diabetes, heart disease, and cancer. More research is needed on this subject. Certainly, however, psychological interventions may be particularly helpful for people with COLD.

Medical Complications from Oxygen Deprivation

Over time, both varieties of COLD cause low oxygen levels ( hypoxia ) and high levels of carbon dioxide ( hypercapnia ) in the body. In order to boost oxygen delivery, the body compensates in a number of ways:

• The rate of breathing increases.
• More red blood cells are produced to increase the blood's oxygen-carrying capacity.
• The heart rate increases to pump more blood.
• Blood vessels in the lung constrict to force blood and oxygen through the circulatory system. This leads to high blood pressure in the lungs ( pulmonary hypertension ).

Eventually these activities can lead to very serious and even life-threatening conditions:

• Patients with prolonged and severe hypoxia and hypercapnia are at risk for acute respiratory failure, which can cause heart rhythm abnormalities or other life-threatening conditions if not treated immediately.
• Abnormally high blood pressure in the lungs can cause a complication called cor pulmonale , in which the right ventricle of the heart enlarges, eventually leading to heart failure.
• The effects of COLD can threaten the heart. Chronic bronchitis itself is associated with a 50% higher risk of death from coronary artery disease, even after considering the effects of smoking.
• Low oxygen levels can also impair mental functioning and short-term memory.

Effects of Respiratory Infections

Any disease that affects the lungs is dangerous for COLD patients. Pneumonia can cause acute attacks of chronic bronchitis. This may precipitate acute respiratory failure, which is life threatening for COLD patients. Viral or bacterial infections in the lungs, seasonal changes, certain medications, and exposure to irritants in the air may also trigger serious lung events.

Other Serious Medical Problems Associated with COLD

The smoking that causes COLD is also associated with high risks of pneumonia, lung cancer, stroke, and heart attacks.

Lung Cancer. Patients with a 30-year history of smoking, who have indications of airflow limitation (in other words, most patients with COLD), are at high risk for lung cancer. In such patients, the incidence of this cancer is 2%. Computed tomography (CT) screening is making it easier to detect this deadly cancer in earlier stages, and such patients should consider having this test.

Sleep Apnea. About half of those with severe COLD experience obstructive sleep apnea, a condition in which breathing stops and starts many times each night. This condition is more serious than previously thought. It has been associated with an elevated risk for hypertension (high blood pressure), stroke, dementia, and pulmonary hypertension.

Osteoporosis. Osteoporosis is a significant problem in patients with COLD. Many conditions associated with COLD (smoking, vitamin D deficiencies, a sedentary lifestyle, the use of corticosteroids) put people at risk for bone density loss and osteoporosis.

• Review Date: 4/28/2006
• Reviewed By: Harvey Simon, M.D., Editor-in-Chief, Associate Professor of Medicine, Harvard Medical School; Physician, Massachusetts General Hospital

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