health

Emphysema is a form of progressive lung disease that is characterized by
chronic shortness of breath and long-term disability. It is sometimes
grouped together with chronic bronchitis under the name of chronic
obstructive pulmonary disease, or COPD. Many people who are diagnosed
with emphysema also have chronic bronchitis.

The High Cost of Emphysema

Emphysema has claimed the lives of many noteworthy
people in the twentieth and twenty-first
centuries:

• Actors: Tallulah Bankhead, Paulette
  Goddard, Robert Mitchum, Vincent Price,
  Barbara Stanwyck, Spencer Tracy
  
• Entertainers: Johnny Carson, Arthur
  Godfrey, Dean Martin, Allan Sherman
  
• Musicians: Leonard Bernstein
  
• Politicians and public figures: William
  O’Neill, Patricia Nixon (wife of President
  Richard Nixon), Coleman Young
  
• Writers and poets: Samuel Beckett,
  William F. Buckley, Jr., Erskine Caldwell, T.
  S. Eliot, Robert Heinlein
  

Emphysema is a lung disease in which a person’s ability to breathe easily
and deeply is steadily weakened over time by the destruction of lung
tissue. The human lung consists of tissue containing millions of tiny air
sacs called alveoli, which are arranged like bunches of grapes around very
small air tubes called bronchioles. There are about 300 million alveoli in
each lung. When a person breathes in air, the air travels from the nose
and mouth through the windpipe and then into the right and left
bronchi, which are the main air passages into each of the two lungs. The
bronchi divide and subdivide repeatedly into smaller and smaller air passages,
finally ending in the bronchioles and alveoli.
In a healthy person, oxygen from the air that has been taken in is
exchanged in the walls of the alveoli for carbon dioxide in the person’s
blood. When the person breathes out, the carbon dioxide leaves the body
in the air that travels out from the lungs and through the upper airway to
the nose and mouth.
To perform its function effectively, the tissue in the lungs that separates
the alveoli from one another needs to be as elastic as possible. The
alveoli contain tiny elastic fibers in their cell walls that allow them to act
like miniature balloons. What happens in emphysema is that smoke or
other irritants causes the alveoli to become inflamed and lose their elasticity.
The bronchioles start to collapse, which traps air inside the alveoli
and overstretches them. In time the alveoli rupture, leading to the formation
of fewer but larger air sacs in the lungs. These larger and less flexible
sacs are less efficient in forcing air out of the lungs when the person
breathes out. As a result, the person has to breathe more frequently or
breathe harder in order to get enough oxygen and get rid of carbon
dioxide.
In addition to the loss of elasticity in the alveoli, the cells in the airways
secrete more mucus than usual, which collects in the airways and
clogs them, making breathing even more difficult.

Emphysema is increasing in the United States and other developed countries
primarily because of cigarette smoking. It is almost entirely a disease
of adults. About 12 million adults in the United States have been diagnosed
with the disease; however, many doctors believe emphysema is
underdiagnosed. Between 4 and 6 percent of male adults and 1 to 3 percent
of female adults are estimated to have emphysema. The number of
women diagnosed with the disease is rising rapidly; the year 2000 was the
first year that more women than men were identified as having emphysema.
About 120,000 people die each year in the United States from
emphysema.
People who develop emphysema as a result of smoking generally start
to have symptoms in their late forties or early fifties. Those who have
emphysema because of a genetic condition (described later) may begin
to have symptoms in their thirties. This genetic condition, known as
alpha 1-antitrypsin deficiency, is more common in Caucasians than in
members of other races and accounts for about 2 percent of all emphysema
cases in the United States.

Some people who do not smoke cigarettes are at increased risk of
emphysema. They include:

• People who work in occupations that expose them to high levels
  of dust from grain or cotton, or chemical irritants. These occupations
  include mining, certain types of agricultural work, and
  lumbering.
  
• People exposed to high levels of automobile exhaust or secondhand
  smoke.
  
• People with certain diseases that affect connective tissue, such as
  Marfan syndrome.
  

Emphysema is caused by a weakening of the tissues in the lungs as a
result of inflammation due to smoke or other chemical irritants in the air,
or a hereditary deficiency of a protein that protects the elasticity of lung
tissue. As the bronchioles in the lungs collapse and the alveoli become
enlarged, the lungs become less efficient in getting rid of carbon dioxide
and the person has to breathe more frequently in order to get enough
oxygen. In addition, the person has to use his or her chest muscles to
expel air from the lungs forcefully rather than being able to rely on the
normal movement of the diaphragm during breathing. This need to use
muscular force leads to the development of a so-called barrel chest; that
is, the person’s chest is almost the same size from front to back as from
side to side.
About 2 percent of cases of emphysema are caused by a deficiency of
a liver enzyme known as alpha 1-antitrypsin, or A1AT. The enzyme ordinarily
protects the alveoli in the lungs from damage by another enzyme
that harms connective tissue. In people with A1AT deficiency, there is
not enough of the protective enzyme to keep the alveoli in good working
condition. A1AT is an inherited condition caused by a mutation in a
gene on chromosome 14.

In addition to shortness of breath, coughing, and wheezing, people
with emphysema often develop the following symptoms:

• Pursed-lips breathing. This is a way of partially closing the lips that
  allows the person to fully exhale. When the mouth opening is
  smaller, the airways that have been weakened by the disease open
  wide and allow the person to expel more air from the lungs.
  
• Greater difficulty exercising or doing work that requires physical
  activity.
  
• Loss of appetite and weight loss. Eating can make it harder to
  breathe because the stomach expands during a meal and pushes
  upward against the diaphragm.
  
• Fatigue. Emphysema leads to a lower level of oxygen in the blood,
  which in turn causes people to feel tired easily.
  
• Slow recovery from such upper respiratory infections as colds
  and flu.

It is important to note that emphysema is a disease that develops gradually;
thus its symptoms may take years to become bothersome enough
to send the patient to their doctor.

Emphysema is most often diagnosed by pulmonary function tests or PFTs.
These are tests in which the patient is asked to breathe into a device called
a spirometer. The spirometer measures how much air the patient’s lungs
can hold and how fast the air moves in and out of the lungs. It can also
be used to determine how well the lungs are exchanging oxygen and
carbon dioxide. Another way the spirometer can be used is to test the effectiveness
of inhaled medications in treating the patient’s emphysema.
Patients are also typically given a chest x ray or computed tomography
(CT) scan to look for damage to lung tissue and the possible presence
of a lung infection. To measure the amount of oxygen and carbon
dioxide in the patient’s blood, he or she may be given a type of blood test
called the arterial blood gases test. This test can help the doctor evaluate
the severity of the patient’s emphysema.

There is no cure for emphysema. Treatment is focused on slowing the
progress of the disease and easing the patient’s symptoms. The first part
of treatment for patients who smoke is to quit the habit.

The next stage in treatment is the use of medications. The doctor
may prescribe one or more of the following types of drugs:

• Bronchodilators. Bronchodilators are drugs that work by
  opening up the airways, which allows for more efficient
  exchange of carbon dioxide and oxygen. Some are taken in tablet
  form while others are dispensed in inhalers. Depending on the
  severity of the person’s emphysema, patients may use the inhaler
  only when needed for shortness of breath or they may take a
  dose of the medication at prescribed regular intervals.
  
• Steroids. This type of medication works by lowering the inflammation
  in the tissues lining the airways. These drugs can also be
  taken in pill form or through inhalers.
  
• Antibiotics. People who have infections in the lungs as well as
  emphysema may be given antibiotics to treat the infections.
  
• Oxygen. Patients who have severe attacks of emphysema may
  need to go to the hospital for oxygen therapy. There are also
  oxygen tanks that can be used in the home; some of these are
  portable units.

Emphysema is sometimes treated surgically. In some cases, part of
the diseased lung is removed. This procedure creates space for the
remaining portions of the lungs; it does improve breathing and quality
of life for some patients. Another surgical option is lung transplantation.
This is a risky procedure, however, and requires the patient to take medications
to prevent the rejection of the transplanted lung. In addition, not
everyone qualifies for transplantation, and those who do are limited by
the short supply of available organs.
Another important part of treatment for emphysema is called pulmonary
rehabilitation. It is aimed at educating patients about their disease
and helping them with lifestyle changes that will slow the
progression of the disease and improve quality of life. Pulmonary rehabilitation
includes a physical exercise program designed to improve the
patient’s physical endurance and energy level. Many patients are also
encouraged to lose weight in order to reduce the burden on their
lungs. One important benefit of pulmonary rehabilitation is psychological:
Patients report that their self-esteem and sense of control over
their life improve when they start to see benefits from the rehabilitation
program.

Emphysema is known to shorten a patient’s lifespan. It is the fourth most
common cause of death in the United States as of 2008, being responsible
for 4.5 percent of all deaths and a contributing factor in another 4.3 percent.
Some patients, however, live longer than others depending on the
cause of their emphysema and the measurement of their lung capacity at
diagnosis. Patients who have smoked twenty cigarettes per day for twenty
years or longer with a severely reduced breathing capacity have the worst
prognosis; only 5 percent survive for twelve years after diagnosis.

Most cases of emphysema can be prevented by simply not smoking or by
quitting smoking as soon as possible and avoiding secondhand smoke.
Emphysema related to genetic factors cannot always be prevented, but its
development can be postponed in people who inherited the defective gene
by avoiding smoking.

Emphysema is likely to continue to rise in the United States because of the
numbers of long-term female smokers who are now getting to the age
when the symptoms of emphysema appear. In addition, the rates of
emphysema around the world are predicted to rise rapidly over the next
few decades as more and more people take up smoking. It is possible that
more effective drugs will be developed to treat emphysema, but a cure for
the disease is unlikely in the near future.