الأربعاء، 22 أغسطس 2012

•Emphysema

Emphysema is a long-term, progressive disease of the lungs that primarily causes shortness of breath due to over-inflation of the alveoli (air sacs in the lung). In people with emphysema, the lung tissue involved in exchange of gases (oxygen and carbon dioxide) is impaired or destroyed. Emphysema is included in a group of diseases called chronic obstructive pulmonary disease or COPD (pulmonary refers to the lungs). Emphysema is called an obstructive lung disease because airflow on exhalation is slowed or stopped because over-inflated alveoli do not exchange gases when a person breaths due to little or no movement of gases out of the alveoli.


Emphysema changes the anatomy of the lung in several important ways. This is due to in part to the destruction of lung tissue around smaller airways. This tissue normally holds these small airways, called bronchioles, open, allowing air to leave the lungs on exhalation. When this tissue is damaged, these airways collapse, making it difficult for the lungs to empty and the air (gases) becomes trapped in the alveoli.
Normal lung tissue looks like a new sponge. Emphysematous lung looks like an old used sponge, with large holes and a dramatic loss of “springy-ness” or elasticity. When the lung is stretched during inflation (inhalation), the nature of the stretched tissue wants to relax to its resting state. In emphysema, this elastic function is impaired, resulting in air trapping in the lungs. Emphysema destroys this spongy tissue of the lung and also severely affects the small blood vessels (capillaries of the lung) and airways that run throughout the lung. Thus, not only is airflow affected but so is blood flow. This has dramatic impact on the ability for the lung not only to empty its air sacs called alveoli (pleural for alveolus) but also for blood to flow through the lungs to receive oxygen.
COPD as a group of diseases ranks as the fourth leading cause of death in the United States. Unlike heart disease and other more common causes of death, the death rate for COPD appears to be rising

Causes of Emphysema
Most emphysema causes involve repeated breathing in of fumes and other things that irritate and damage the lungs and airways.
 
Specific causes of emphysema can include:
 
  • Cigarette smoking
  • Pipe, cigar, and other types of tobacco
  • Certain fumes or dust
  • Genetic factors.
     
Smoking
Cigarette smoking is the most common irritant that causes emphysema. Pipe, cigar, and other types of tobacco smoking can also cause emphysema, especially if the smoke is inhaled.
 
Fumes and Dust
Breathing in other fumes and dusts over a long period of time may also cause the disease. The lungs and airways are highly sensitive to these irritants. They cause the airways to become inflamed, narrowed, and destroy the elastic fibers that allow the lung to stretch, then come back to its resting shape. This makes breathing air in and out of the lungs more difficult.
 
Other things that may irritate the lungs and contribute to emphysema include:
 
  • Working around certain kinds of chemicals and breathing in the fumes for many years
  • Working in a dusty area over many years
  • Heavy exposure to air pollution
  • Being around secondhand smoke (smoke in the air from other people smoking cigarettes).
     
Genetic Factors
Genes (tiny bits of information in your body's cells passed on by your parents) may play a role in developing emphysema.
 
In rare cases, emphysema is caused by a gene-related disorder called alpha-1 antitrypsin deficiency. Alpha-1 antitrypsin is a protein in your blood that inactivates destructive proteins in the blood. People with antitrypsin deficiency have low levels of alpha-1 antitrypsin; the imbalance of proteins leads to the destruction of the lungs. If people with this condition smoke, the disease progresses more rapidly.
 

Emphysema Risk Factors

Most people with emphysema are smokers or were smokers in the past. People with a family history of emphysema are more likely to get the disease if they smoke. The chance of developing emphysema is also greater in people who have spent many years in contact with lung irritants such as:
 
  • Air pollution
  • Chemical fumes, vapors, and dusts usually linked to certain jobs.
     
A person who has had frequent and severe lung infections, especially during childhood, may have a greater chance of developing lung damage that can lead to emphysema. Fortunately, this is much less common today, thanks to antibiotic treatments
 
Symptoms
 

Emphysema Symptoms: Breathlessness Most Common

Shortness of breath is by far the most common of emphysema symptoms. Most people with emphysema first notice something's wrong when they become winded during a previously routine activity. This might be climbing stairs or mowing the lawn.
The shortness of breath in emphysema results from structural changes in the lungs. These occur over years in response to lung damage, usually from smoking:
  • The linings between air sacs are destroyed, creating air pockets in the lungs.
  • Air is trapped in these air pockets and is difficult to breathe out.
  • The lungs slowly enlarge, and breathing takes more effort.
In people with emphysema, the muscles responsible for breathing have to work harder, and tire out sooner. The result is feeling breathless -- at first with activity -- and at rest in advanced emphysema.

Other Emphysema Symptoms

Virtually everyone with emphysema experiences shortness of breath, especially with exertion. Many people with emphysema develop some of the other emphysema symptoms:
  • Wheezing: This symptom of emphysema is shared with asthma. Wheezing often improves with inhaled medicines called bronchodilators.
  • Cough: A large proportion of people with emphysema experience a cough. Often this is related to smoking. However, cough can persist as one of the symptoms of emphysema after quitting smoking.
  • Chest tightness or pain: These may be symptoms of emphysema or of coexisting heart disease. Chest tightness occurs more often with exercise or during periods of breathlessness.
People with emphysema may also face some other less common emphysema symptoms:
  • Loss of appetite and weight loss
  • Depression
  • Poor sleep quality
  • Decreased sexual function
These symptoms of emphysema occur more often in its advanced stages.

Symptoms of Emphysema Are Slowly Progressive

Symptoms of emphysema are progressive, meaning they can be expected to get worse over time. The rate at which breathlessness worsens depends mainly on whether someone with emphysema continues to smoke.
The lungs slowly lose function with age, even in nonsmokers. In people with emphysema, smoking accelerates this loss of lung function. If a smoker with emphysema quits, he or she can reduce the rate of decline to that of a nonsmoker.
Most people experience the onset of emphysema slowly and gradually. In smokers who develop emphysema, symptoms usually begin between age 45 and 60.
It's difficult to predict the rate of progression of emphysema symptoms. Much is unknown about why emphysema occurs and in whom.
In some people, emphysema symptoms progress faster than in others. It's believed that genetic factors make some people more vulnerable to developing emphysema. Genetics may also cause some people's emphysema symptoms to progress more rapidly.
The majority of people with emphysema, though, can expect relatively slow progression of emphysema symptoms, provided they quit smoking.

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