What is chronic obstructive pulmonary disease (COPD)?

Causes and Symptoms

Patients suffering from chronic obstructive pulmonary disease (COPD), a
combination of chronic bronchitis and emphysema,
have a chronic cough and shortness of breath that progressively limits their
tolerance for physical activity. A physical examination may appear normal in the
early stages of COPD, but as the disease progresses, tachypnea and wheezing occur.
Over time, the occasional cough becomes more frequent, and greater effort is
exerted to breathe. In later stages of COPD, the circulatory system may be
affected because the lungs can no longer supply an adequate amount of oxygen to
the body. Other signs of advanced COPD are a barrel chest, pursed lip breathing,
and a prolonged expiratory phase of respirations. Coughing produces phlegm that
becomes increasingly difficult to expel as it thickens. Persons with advanced COPD
cannot lie flat to sleep and may need to sit in an semiupright position in order
to breathe.

The major risk factor for COPD is cigarette smoking. Other risk factors are
air
pollution (including exposure to mining), occupational
exposures (such as organic and inorganic dusts, chemical agents, and fumes), a
history of childhood respiratory infections, and active asthma. In
chronic bronchitis, the lining of the bronchial tubes become irritated, inflamed,
and filled with mucus that blocks the airways, making it difficult to breathe. In
emphysema, the alveoli become irritated, stiffen, and cannot transfer oxygen and
carbon dioxide in the blood. Thus far, a deficiency of the enzyme
alpha-1 antitrypsin is the best documented genetic cause of
COPD.

COPD is a progressive disease that presents few symptoms until it is well
developed in the lungs. It is usually not identified until the patient is fifty to
sixty years old, although COPD caused by a deficiency of alpha-1 antitrypsin may
be identified by thirty to forty years of age.

Confirmation of the diagnosis of COPD is made by pulmonary function tests (PFTs).
PFTs are helpful in diagnosing COPD in its early stages and may be helpful in
convincing patients to consider smoking cessation, if necessary, to
slow the progression of COPD. Spirometry measures the amount of air
exhaled in one second, or forced expiratory volume (FEV1). The total amount of air
exhaled, or forced vital capacity (FVC), is compared to the FEV1 to determine the
extent of airway obstruction. A peak flow meter can show the severity of breathing
impairment; after a deep breath, the patient blows into the instrument as
forcefully and for as long as possible. Arterial blood gas tests measure the level
of oxygen and carbon dioxide in the blood. Serum alpha-1-antitrypsin levels are
measured by blood samples. Finally, chest X-rays, pulmonary ventilation-perfusion
scans, and chest magnetic resonance imaging (MRI) scans may all help to identify
the degree of lung damage caused by COPD, including bronchial wall thickening,
ill-defined opacities in the parenchyma, and prominent vessels.

Treatment and Therapy

Because no cure exists for COPD, treatment focuses on decreasing symptoms and
reducing complications. Bronchodilator medications, antibiotics, corticosteroids, oxygen therapy, and vaccination against
pneumonia and influenza are used to treat or prevent symptoms, slow the
progression of the disease, and manage any complications. In addition to
corticosteroids, medications for the management of COPD include short-acting
inhaled anticholinergics, short-acting inhaled beta-2 agonists
(SABA), and long-acting beta-2 agonists (LABA). Smoking cessation is vitally
important for slowing the progress of COPD. Nicotine replacement therapy,
antidepressants such as bupropion, and counseling are some of
the methods used to assist in smoking cessation.

Patients with COPD who are hypoxic may require long-term oxygen
therapy to improve their functional status and rate of
survival. The purpose of oxygen therapy is to maintain adequate oxygen levels to
prevent respiratory difficulties.

Pulmonary rehabilitation can help reduce hospitalizations and increase the quality
of life for those with COPD, improving their overall functional status. Pulmonary
rehabilitation includes therapies to enhance breathing, exercise training to
improve muscle strength and stamina, and self-management education. Pursed lip
breathing helps to relieve abnormal breathing (dyspnea) and to slow
respirations.

Lung transplantation and lung volume reduction surgery (LVRS) may be options for
people who suffer from severe emphysema. Lung volume reduction surgery involves
the partial removal of the most damaged areas of the lungs in order to allow for
better lung expansion of the normal areas of the lung. Gene therapy and
alpha-1-antitrypsin augmentation therapy are presently under evaluation as
treatments for alpha-1-antitrypsin deficiency. The American Thoracic Society and
the European Respiratory Society recommend IV alpha-1-antitrypsin augmentation
therapy for alpha-1-antitrypsin deficiency in patients with airflow obstruction or
with acute rejection or infection following lung transplant.

Perspective and Prospects

The primary cause of COPD is tobacco smoke—either through smoking or
secondhand
smoke exposure. According to the American Lung Association,
COPD is the third leading cause of death in the United States, following cancer
and heart disease. The American Lung Association estimates that 12.7 million
American adults have been diagnosed with COPD but holds that COPD is
underdiagnosed in the United States and estimates that as many as 24 million
Americans have evidence of impaired lung function.

According to the World Health Organization (WHO), COPD was the third leading cause
of death worldwide in 2012, following ischemic heart disease and stroke and tied
with lower respiratory infections. The incidence of this disease is increasing
every year; in 2002, COPD was the fifth leading cause of death, according to the
WHO. Those with COPD are prone to recurrent respiratory infections, and their
quality of life gradually declines as the disease worsens. Smoking cessation is
the single most important prevention method. Exposure to indoor air pollution,
particularly from the use of biomass fuels for cooking and heating, is the leading
risk factor for COPD in low-income countries.

Bibliography:

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