COPD (Chronic Obstructive Pulmonary Disease) (cont.)

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What causes COPD?

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The primary cause of COPD is cigarette smoking or exposure to tobacco smoke. It is estimated that 90% of the risk for development of COPD is related to tobacco smoke. The smoke can also be secondhand smoke (tobacco smoke exhaled by a smoker and then breathed in by a non-smoker).

Other causes of COPD are related to air pollution, such as that seen with burning coal or wood and with industrial air pollutants.

Infectious diseases that destroy lung tissue and patients with hyperactive airways or asthma may also contribute to causing this disease.

The physical changes or causes are airway obstruction by thick mucus or by poor lung tissue compliance (the elasticity, or ability of the lung tissue to expand) that can either block air from entering the alveoli or by not permitting the alveoli to expel CO2 because the elastic tissue becomes nonfunctional. The overall result is that oxygen in the air cannot get by obstructions (for example, thick mucus plugs) to reach alveoli; or as is the case with emphysema or alpha-1 antitrypsin deficiency, the oxygen or air that reaches alveoli cannot be expelled. In either case, the exchange of oxygen and carbon dioxide that usually occurs in healthy alveoli is either inhibited or prevented. Consequently, the person exhibits a progressive difficulty, first coughing to remove obstructions like mucus, and then in breathing, especially with exertion.

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What are the signs and symptoms of COPD?

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COPD is a slowly progressive disease so it is not unusual for the initial signs and symptoms to be a bit different from those in the late stages of the disease. There are many ways to evaluate or stage COPD, often based on symptoms.

Usually the first signs and symptoms of COPD include a productive cough usually in the morning, with colorless sputum (mucus). Individuals who may develop sudden or severe (acute) chest pain should be evaluated at an emergency department to be sure there is no cardiac problem that causes symptoms similar to COPD.

Perhaps the most significant symptom of COPD is breathlessness, termed shortness of breath (dyspnea). Early on, this symptom may occur occasionally with exertion and eventually may progress to breathlessness while doing a simple task such as standing up, or walking to the bathroom. Some people may develop wheezing (a whistling or hissing sound while breathing).

There have been efforts to stage COPD based on symptoms and other measures. One of the most recent efforts is the Global Initiative for Chronic Obstructive Lung Disease program (GOLD). The staging is based on the results of a pulmonary function test. Specifically, the forced expiratory volume in one second (FEV1) of a standard predicted value is measured, based on the individual patient's physical parameters. The staging of COPD by this method is as follows:

  • Stage I is FEV1 of equal or more than 80% of the predicted value
  • Stage II is FEV1 of 50% to 79% of the predicted value
  • Stage III is FEV1 of 30% to 49% of the predicted value
  • Stage IV is FEV1 of less than 30% of predicted value or an FEV1 less than 50% of predicted value plus respiratory failure

Other staging methods are similar but are based on the severity of the shortness of breath symptom that is sometimes subjective. The above staging is measurable objectively, providing the patient is putting forth their best effort.

Medically Reviewed by a Doctor on 3/18/2014

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