Alpha-1 Lung Disease
Not everyone who has A1AD will develop lung problems and researchers are still trying to understand why some people do and some don’t. Factors are smoking, lung infections and workplace exposures to dust and fumes.
When to Suspect Alpha-1 Lung Disease
Alpha-1 Lung Disease should be suspected in people who have early onset Chronic Obstructive Pulmonary Disease (COPD); that is, in people in their forties or younger or in people with COPD who have not smoked or have smoked very little. It should also be suspected if there is a certain pattern of emphysema that shows up on a chest x-ray – basilar emphysema (emphysema in the bottom of the lungs) or a family history of emphysema. Alpha-1 should also be considered in asthma that’s tough to treat particularly if the lung function doesn’t return to normal with treatment. Recurring respiratory infections might be a sign of a different sort of Alpha-1 lung damage known to doctors as bronchiectasis.
How does the lung problem happen?
Imagine the lungs as a country. An enemy (cigarette smoke, including second-hand smoke, infection, or a variety of chemical or environmental pollutants) invades this country. These invaders are immediately detected by the home guard, otherwise known as white blood cells that spring automatically into action. The white blood cells release an enzyme, called neutrophil elastase (NE), which storms into battle. It has one mission and that is to destroy anything in its way – cigarette smoke, infection, etc. This is the good news. The bad news is that it doesn’t know when to stop. Once it has destroyed all enemy invaders, it will begin to attack and destroy healthy lung tissue.
It is the job of Alpha-1 Antitrypsin (AAT) to stop, or inactivate, the NE when it has done its job. People with Alpha-1 do not have enough AAT to protect them from the destructive tendencies of NE. It seems strange that NE, something that was initially so helpful, can become extremely harmful without proper controls. That proper control is sufficient AAT.
Lung Function Tests
Aside from the tests to detect Alpha-1, there are a number of tests to determine lung function. Among the most frequently used are:
These tests determine how much air can be breathed in and out (volume) and how rapidly the movement of air can be (flow rate) especially during exhalation. Normal or predicted values are determined through studies of people who have no lung disease and who are the same height, sex, ethnic background and age as the patient.
The patient is asked to blow into a machine as deeply and forcefully as possible and the best score of three or four attempts is recorded. Often, the patient is given a bronchodilator and the tests are repeated about fifteen minutes later. The pre- and post-bronchodilator tests are compared to see if there has been any change. Results are recorded as actual scores and as percentages when compared normal or predicted values. The most common measures are:
Forced Expiry Volume in one second (FEV1)
This is the amount of air that can be blown out in the first second. A lower result than that expected (that is, in comparison with the reference group of people of the same sex, height, etc) may indicate problems.
Forced Vital Capacity (FVC)
This is the total amount of air that can be blown out. It is registered on the computer as a graph showing the flow volume curve or loop. The shape of this graph can help determine the type of lung disease, if any, that may be present.
Ratio of FEV1 to FVC (FEV1/FVC)
This is reported as a percentage and is determined by dividing the actual FEV1 by the actual FVC. The normal ratio ranges from 70-85% but declines with age. In obstructive diseases, such as Alpha-1, the ratio is usually lower than normal.
This test measures how efficiently the lungs, and specifically the alveoli (air sacs), are taking in oxygen. For people with Alpha-1 the diffusing capacity will be lower than normal as there is less lung surface available for the gas exchange to take place.
Arterial Blood Gas
A sample of blood is drawn from an artery (usually one near the wrist) to determine how well oxygen is getting into the blood and carbon dioxide is getting out.
95 – 98 mmHg
less than 55 mmHg
Carbon Dioxide (PaCO2)
37 – 43 mmHg
more than 50 mmHg
Acid Base Balance (pH)
7.37 – 7.43
less than 7.30
(Reference: Hodder & Lightstone, p. 56)
Pulse Oximetry (SaO2)
This test is done with a finger or ear probe and determines the percentage of oxygen in the blood. A reading of 93-100% is considered within normal range. Critical levels are considered to be less than 85-88%. The pulse oximeter is not as accurate as the arterial blood test but is much easier to administer.
For More Information
There are many good web sites that cover Alpha-1, among the better ones is the Alpha -1 Foundation. Hodder & Lightstone’s book, Every Breath I Take: A Guide to Living with COPD (see the Publications Section for details) is also an excellent source of information.