What is emphysema?
Emphysema is a condition that forms part of chronic obstructive pulmonary disease (COPD) and involves the enlargement of the air sacs in the lung.2-4
The alveoli at the end of the bronchioles of the lung become enlarged because of the breakdown of their walls. The fewer and larger damaged sacs that result mean there is a reduced surface area for the exchange of oxygen into the blood and carbon dioxide out of it.2-4
The damage is permanent - not reversible - and it causes reduced respiratory function and breathlessness. The damage takes a number of forms - the sacs can be destroyed, narrowed, collapsed, stretched or over-inflated.2-5
Causes of emphysema
The biggest known cause or risk factor for emphysema - and for COPD - is smoking.4,6-8 Cigarette smoking is responsible for around 90% of cases of COPD.7However, COPD will develop only in smokers who are genetically susceptible - smoking does not always lead to the disease.Other inhaled toxins also lead to emphysema and COPD, including work-related ones. In developing countries, smoke from indoor cooking and heating is also an important cause.7,8
While the following are not as important as primary cigarette smoke exposure, they are minor contributory risk factors:4,7,8
- Low body weight
- Childhood respiratory disorders
- Exposure to passive cigarette smoke
- Air pollution
- Occupational dust (mineral dust, cotton dust, for example)
- Inhaled chemicals (coal, grains, isocyanates, cadmium, for example).
Genetics are responsible for a rare form of COPD - emphysema can be caused by ?1-antitrypsin deficiency. The protein is necessary for protecting the lungs against neutrophil elastase destruction of alveolar tissue.8,9 The deficiency is congenital - that is, people are born with it.
The genetic disease affects non-smokers, explaining some of the cases, with onset earlier in life, of COPD that are not caused by smoking. Smoking does, however, accelerate genetically predisposed cases of emphysema.8
Symptoms of emphysema
Two symptoms are the main markers of emphysema and present early on:4,9,10
Shortness of breath is also known as dyspnea and gives the feeling of being unable to catch a breath. This symptom may be present only during physical exertion but as the disease progresses may be present during rest, too - emphysema and COPD take years to develop and progress.8-10
Other symptoms may be experienced, especially in more advanced lung disease:4,6,8,10
- Frequent lung infections
- Producing a lot of mucus (phlegm or sputum)
- Reduced appetite
- Weight loss
- Blueness of the lips or fingernail beds (from cyanosis caused by poor respiration)
- Anxiety, depression
- Sleep problems
- Morning headache signals nighttime breathing difficulty (nocturnal hypercapnia or hypoxemia)
Many of the symptoms of emphysema and COPD are shared by other medical conditions; it is important to seek a doctor's examination and diagnosis.
Tests and diagnosis of emphysema
Specific tests are used to identify emphysema and COPD, and doctors also perform physical examinations and "take histories" (ask questions about the problem) to support a diagnosis. This also helps to differentiate it from other conditions such as asthma and heart failure.8
If the cause of the emphysema is thought to be a rare case of ?1-antitrypsin deficiency - there has been no smoking or other typical risk factor, for example, or a close relative has the deficiency - a laboratory test can be ordered to diagnose this.11
Lung function tests
Lung function tests - also called pulmonary function tests - are used to confirm a diagnosis of emphysema.8,10 They measure the capacity of the lungs to exchange respiratory gases and include spirometry.
Lung function testing is used to:8
A chest X-ray may be ordered during diagnosis.
- Confirm airflow limitation
- Quantify the severity and reversibility (in response to drugs) of the limitation
- Differentiate COPD from other respiratory disorders.
Lung function tests also help to monitor the progression of the disease and to assess response to treatment.8
Spirometry assesses airflow obstruction and is measured according to the reduction in forced expiratory volume after bronchodilator treatment.7
For the test, patients blow as fast and hard as possible into a tube attached to a machine that measures the volume and speed of air blown out.6
Forced expiratory volume in one second is abbreviated to FEV1. Four stages of COPD from mild to severe are determined by the percentage of predicted (average healthy) values.7
Other tests used by doctors in the process of diagnosing COPD and emphysema include imaging of the lungs via chest X-ray or CT scanning (computed tomography), and arterial blood gas analysis to assess O2/CO2 exchange.6,10