Emphysema

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What is Emphysema?

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Emphysema is a chronic disease affecting the lungs. People have two lungs as demonstrated in the diagram below. The lungs receive air that travels from the nose and mouth, through the trachea (windpipe) and to the smaller airways.

The lungs consist of a series of folded membranes (the alveoli) which are located at the ends of very fine branching air passages (bronchioles). The alveoli are responsible for the absorption of oxygen and removal of carbon dioxide from the body.

Emphysema involves abnormal permanent enlargement of the tiniest airspaces of the lungs, the alveoli and respiratory bronchioles. There is also destruction of the walls of these airspaces. Emphysema usually occurs with chronic bronchitis as part of the disease complex known as Chronic Obstructive Pulmonary Disease (COPD). There is significant overlap between chronic bronchitis and emphysema.

Below is a postmortem lung specimen of a chronic emphysema sufferer.

Who gets Emphysema?

Emphysema, along with chronic bronchitis (together known as COPD) is a major cause of disability, hospital admissions, and mortality. More than half a million Australians are estimated to suffer from moderate to severe disease, and COPD ranks fourth among the common causes of death in Australian men, and sixth in women. The global prevalence is quoted at 7.5% of which 1.8% have emphysema alone.

COPD occurs in 18% of male and 14% of female smokers and in 7% and 6% respectively in people who have never smoked. Emphysema has a strong relationship with cigarette smoking and smokers tend to have more severe disease.

Predisposing Factors

Cigarette smoke is by far the most important factor in the development of emphysema and COPD. Those who smoke 30 cigarettes per day are 20 times more likely to die from COPD than non-smokers.
About 2% of cases of emphysema are due to hereditary deficiency of the alpha-1 antitrypsin gene. This gene abnormality occurs in about 1 in 5000 people, but does not always cause disease. Alpha-1 antitrypsin is an important enzyme in the lung that prevents destruction of the alveoli walls.

Progression

Nearly all sufferers of emphysema are smokers or have smoked in the past. In susceptible smokers, cigarette smoking results in a steady decline in lung function. Smoking cessation, even late in the course of the disease may result in mild improvement in lung function, and more importantly it will slow the rate of decline in lung function.

Emphysema usually presents in about the fifth decade although you may recall some breathing troubles prior to this time. If you have a deficiency in the alpha-1 antitrypsin gene your disease may present even earlier.

In general emphysema gradually causes a decline in function and you may notice you become less capable of performing normal activities. Impairment increases as the disease progresses, but it may go unrecognised until later. In advanced stages of disease patients can become short of breath even at rest which is particularly disabling for patients. Emphysema sufferers also have a lower expected life expectancy than the general population.

Possible complications of emphysema include:

Secondary polycythaemia (abnormally high amount of red blood cells causing sluggish blood flow and an increased risk of clotting).
Right heart failure.
Pneumothorax (escape of air from the lung into the pleural cavity).
Respiratory failure- Often caused by acute infections of the lungs.

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