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Emphysema

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.

Symptoms

Shortness of breath is the most common symptom of emphysema. Cough, sometimes caused by the production of mucus, and wheezing may also be symptoms of emphysema. You may notice that your tolerance for exercise decreases over time. 

 

Emphysema usually develops slowly. You may not have any acute episodes of shortness of breath. Slow deterioration is the rule, and it may go unnoticed. This is especially the case if you are a smoker or have other medical problems that limit your ability to exercise.

 

One of the hallmark signs of emphysema is "pursed-lipbreathing". The person with emphysema struggles to exhale completely, in an attempt to empty trapped air. They purse their lips, leaving only a small opening. Then, when they exhale, the lips block the flow of air, increasing pressure in the collapsed airways, and opening them, allowing the trapped air to empty.

 

People with emphysema may develop a "barrel chest", where the distance from the chest to the back, which is normally less than the distance side to side, becomes more pronounced. This is a direct result of air becoming trapped behind obstructed airways.

Causes

Cigarette smoking is by far the most dangerous behavior that causes people to develop emphysema, and it is also the most preventable cause. Other risk factors include a deficiency of an enzyme called alpha-1-antitrypsin, air pollution, airway reactivity, heredity, male sex, and age. 

 

  • The importance of cigarette smoking as a risk factor for developing emphysema cannot be overemphasized. Cigarette smoke contributes to this disease process in two ways. It destroys lung tissue, which results in the obstruction of air flow, and it causes inflammation and irritation of airways that can add to air flow obstruction.
  1. Destruction of lung tissue occurs in several ways. First, cigarette smoke directly affects the cells in the airway responsible for clearing mucus and other secretions. Occasional smoking temporarily disrupts the sweeping action of tiny hairs called cilia that line the airways. Continued smoking leads to longer dysfunction of the cilia. Long-term exposure to cigarette smoke causes the cilia to disappear from the cells lining the air passages. Without the constant sweeping motion of the cilia, mucous secretions cannot be cleared from the lower respiratory tract. Furthermore, smoke causes mucous secretion to be increased at the same time that the ability to clear the secretions is decreased. The resulting mucous buildup can provide bacteria and other organisms with a rich source of food and lead to infection. 
  2. The immune cells in the lung, whose job it is to prevent and fight infection, are also affected by cigarette smoke. They cannot fight bacteria as effectively or clear the lungs of the many particles (such as tar) that cigarette smoke contains. In these ways cigarette smoke sets the stage for frequent lung infections. Although these infections may not even be serious enough to require medical care, the inflammation caused by the immune system constantly attacking bacteria or tar leads to the release of destructive enzymes from the immune cells. 
  3. Over time, enzymes released during this persistent inflammation lead to the loss of proteins responsible for keeping the lungs elastic. In addition, the tissue separating the air cells (alveoli) from one another also is destroyed. Over years of chronic exposure to cigarette smoke, the decreased elasticity and destruction of alveoli leads to the slow destruction of lung function.

 

  • Alpha-1-antitrypsin (also known as alpha-1-antiprotease) is a substance that fights a destructive enzyme in the lungs called trypsin (or protease). Trypsin is a digestive enzyme, most often found in the digestive tract, where it is used to help the body digest food. It is also released by immune cells in their attempt to destroy bacteria and other material. People with alpha-1-antitrypsin deficiency cannot fight the destructive effects of trypsin once it is released in the lung. The destruction of tissue by trypsin produces similar effects to those seen with cigarette smoking. The lung tissue is slowly destroyed, thus decreasing the ability of the lungs to perform appropriately. The imbalance that develops between trypsin and antitrypsin results in an “innocent bystander” effect. Foreign objects (e.g. bacteria) are trying to be destroyed but this enzyme destroys normal tissue since the second enzyme (antiprotease) responsible for controlling the first enzyme (protease) is not available or is poorly functioning. This is referred to as the “Dutch” hypothesis of emphysema formation.

 

  • Air pollution acts in a similar manner to cigarette smoke. The pollutants cause inflammation in the airways, leading to lung tissue destruction. 

 

  • Close relatives of people with emphysema are more likely to develop the disease themselves. This is probably because the tissue sensitivity or response to smoke and other irritants may be inherited. The role of genetics in the development of emphysema, however, remains unclear. 

 

  • Abnormal airway reactivity, such as bronchial asthma, has been shown to be a risk factor for the development of emphysema. 

 

  • Men are more likely to develop emphysema than women. The exact reason for this is unknown, but differences between male and female hormones are suspected. 

 

  • Older age is a risk factor for emphysema. Lung function normally declines with age. Therefore, it stands to reason that the older the person, the more likely they will have enough lung tissue destruction to produce emphysema.

 

It is important to emphasize that COPD is often not purely emphysema orbronchitis, but varying combinations of both.

Treatment

Treatment for emphysema can take many forms. Different approaches to treatment are available. Generally, a doctor will prescribe these treatments in a step-wise approach, depending on the severity of your condition.

 

  • Stop smoking: Although not strictly a treatment, most doctors make this recommendation for people with emphysema (and everyone). Quitting smoking may halt the progression of the disease and should improve the function of the lungs to some extent. Lung function deteriorates with age. In those susceptible to developing COPD, smoking can result in a five-fold deterioration of lung function. Smoking cessation may return lung function from this rapid deterioration to its normal rate after smoking is stopped. A doctor may be able to prescribe medications to help in breaking theaddiction and can also recommend behavioral therapies, such as support groups. You and your doctor should work to find an approach that results in the successful end to cigarette smoking and, in the process, the beginning of improved lung function and quality of life. 

 

  • Bronchodilating medications: These medications, which cause the air passages to open more fully and allow better air exchange, are usually the first medications that a doctor will prescribe for emphysema. In very mild cases, bronchodilators may be used only as needed, for episodes of shortness of breath. 
  1. The most common bronchodilator for mild cases of emphysema isalbuterol (Proventil or Ventolin). It acts quickly, and 1 dose usually provides relief for 4-6 hours. Albuterol is most commonly available as ametered-dose inhaler or MDI, and this is the form that is used most often for patients with mild emphysema, with intermittent shortness of breath. When used for this purpose, some people refer to their albuterol inhaler as a "rescue" medication. It acts to rescue them from a more serious attack of shortness of breath. 
  2. If you have some degree of shortness of breath at rest, a doctor may prescribe the albuterol to be given at regularly scheduled intervals, either through the MDI, or by nebulization. Nebulization involves breathing in liquid medication that has been vaporized by a continuous flow of air (in much the same way a whole-room vaporizer causes liquid droplets to enter the air by the flow of air through water). Nebulized albuterol may be prescribed once scheduled doses via inhaler are no longer adequate to alleviate shortness of breath. 
  3. Ipratropium bromide (Atrovent) is another bronchodilating medication that is used for relatively mild emphysema. Similar to albuterol, it is available in both an inhaler and as a liquid for nebulization. Unlike albuterol, however, ipratropium bromide is usually given in scheduled intervals. Therefore, it is not usually prescribed for "rescue" purposes. Atrovent lasts longer than albuterol, however, and often provides greater relief. Tiotropium (Spiriva) is a long acting form of ipratropium. This once a day medicine has shown to result in a fewer hospitalizations and possible increased survival in some patients with COPD. 
  4. Methylxanthines (Theophylline) and other bronchodilating medications are available that have varying properties that may make them useful in certain cases. Theophylline (Theo-Dur, Uniphyl) is a medication given orally (tablets). It can have a sustained effect on keeping air passageways open. Theophylline levels must be monitored by blood tests. This medicine is used less frequently today due to its narrow therapeutic window. Too much theophylline can produce an overdose; too little, and there will not be enough relief of shortness of breath. In addition, other drugs can interact with theophylline, altering the blood level without warning. For this reason, doctors now prescribe theophylline after very carefully considering its potential for other drug interactions. If you take theophylline, take the medication as prescribed and check with your doctor before starting any new medication. Some new studies are suggesting that very low dose theophylline may have anti-inflammatory properties as well. Theophylline used to be widely prescribed; currently it is prescribed infrequently and usually only in special circumstances because of its narrow range of effectiveness, necessity of blood level monitoring and its interactions with other drugs.

 

  • Steroid medications: They decrease inflammation in the body. They are used for this effect in the lung and elsewhere and have been shown to be of some benefit in emphysema. However, not all people will respond to steroid therapy. Steroids may either be given orally or inhaled through an MDI or another form of inhaler. 

 

  • Antibiotics: These medications are often prescribed for people with emphysema who have increased shortness of breath. Even when the chest x-ray does not show pneumonia or evidence of infection, people treated withantibiotics tend to have shorter episodes of shortness of breath. It is suspected that infection may play a role in an acute bout of emphysema, even before the infection worsens into a pneumonia or acute bronchitis.
  1. Data now suggests that when patients with COPD have a sudden worsening of their symptoms of cough and shortness of breath (also termed an exacerbation), brief and immediate use of steroids and antibiotics can reduce hospitalizations.

 

  • Oxygen: If you have shortness of breath and go to a hospital's emergency department, you often are given oxygen. It may even be necessary to give oxygen by placing a tube in your windpipe and allowing a machine to assist your breathing (also termed tracheal intubation). In some cases, it may be necessary for you to receive oxygen at home as well. There are home-based oxygen tanks available and portable units that enable you to be mobile and engage in normal day-to-day activities.
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