First draft. Informed comment is invited.
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WHAT IS ASTHMA?
Asthma is a physical condition causing mild to severe difficulties with breathing. The condition involves narrowing of the airways into the lungs, reducing the flow of air.
Strictly speaking, asthma is a difficulty breathing out, and other conditions cause other breathing problems. Collectively, asthma and related conditions are referred to as COPD, or
Strictly, we should say "asthma and COPD". The main diseases of COPD are chronic bronchitis, and emphisema.
There are various other lung diseases (as well as cancer) which involve damage to the membrane between the air and the bloodstream inside the lung. This is where the transfer of oxygen to the blood and carbon dioxide from the blood take place. These are not our primary concern, but we plan to include links for further information. (when information is available)
There are various causes of asthma attacks (which may range from a mild annoyance to life-threatening). Most are allergic reactions. Asthma may also be induced by excercise, when the airways are irritated by the faster flow of air. This is often seasonal, and worst in cold or hot DRY air.
A common allergen is house dust mite. Others include pets, tobacco smoke, and various forms of pollution including diesel fumes.
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SYMPTOMS
The main symptoms of asthma are :-
It is possible for severe asthmatics to have over-inflated lungs, because the restricted flow means they do not empty their lungs properly when breathing out. Most people can exhale about 75% of the air in their lungs, leaving about 25% residual. Some asthmatics breathe out only as little as 25%, leaving 75% residual air in their lungs. One consequence is that they have limited transfer of fresh oxygen to their bloodstream.
Breathlessness and chest pain are also symptoms of heart problems. If you have these symptoms and have not yet seen your Doctor, it may be time to go and get a proper diagnosis.
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MEASURING ASTHMA
There is a simple measurement for Asthma which provides some guide to its severity. PEAK FLOW is the highest flow rate which can be achieved breathing out. The peak flow meter is a simple device which measures this. It is available on prescription, or may be bought for under £10. The chest clinic has more accurate equipment for measuring peak flow and other aspects of lung function.
The unit of measurement is litres per minute. Roughly speaking, children have peak flows in the range 200 to 500, while adults are in the range 400 to 700. Some patients with severe asthma can have peak flows around 200. This is not normal, but a disabling level of asthma, requiring high levels of medication to survive.
The basic value of peak flow is different in different people, and you should get used to your own reading. For example, someone may have a usual peak flow reading of 650, and may feel uncomfortably asthmatic with a reading of 550. But 500 may be someone else's normal peak flow.
The variation in peaks flow is the indicator of severity of asthma. Check your peak flow regularly, and note the value. Agree with your Doctor how much of a drop is acceptable, and how much should be taken as a warning to seek medical advice. In general, if your peak flow has dropped by 20% or more you should consult your Doctor. Normal daily variations may be 5%, occasionally 10%. But a drop of 10% is a clear warning sign.
It can be instructive to measure your peak flow every hour for a day. Most people have a lower peak flow when they wake up in the morning than for the rest of the day. But exposure to particular triggers may reveal what can cause you to have an asthma attack. Along with your record of hourly peak flow, note anything you think may have caused variations. Note also what medication you have taken since the last reading.
Your doctor may also have an instrument called a spirometer. This is more sophisticated than a simple peak flow meter and is capable of measuring both how much air you can breath out (in one breath), and how much you breath out in the first second. (This measurement is called FEV 1. (one)). This and other lung testing instruments are used at specialist chest clinics.
We hope to have available a more comprehensive paper from an expert on lung function measurements. This is an interesting topic for wider study.
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TREATMENT
There is no cure for asthma, but there are many treatmants to relieve the symptoms.
The main types of medication are:-
Most are inhaled, but there are a few which are taken in tablet or solution.
Preventers are usually packaged in brown containers (but other colours including white and green are also used). They should be used daily. Their main function is to reduce the sensitivity of the airways to the trigger factors which cause asthma attacks.
Relievers are usually packaged in blue containers. They should be used as required, and may also be used before using preventers. They reverse the narrowing of the airways, allowing more normal air flow into and out of the lungs. Using a reliever about 5 minutes before taking inhaled preventers allows more of the preventer medication to reach the lungs.
In some cases, a small machine called a nebuliser is required to deliver the medication. Your Doctor and Asthma Support Nurse will make sure that you know the proper method of taking your medication.
Your doctor will assess and prescribe your normal dose of medication, which depends upon how severe your asthma is. This should not be changed except as instructed by your doctor. When asthma is controlled by medication, it is tempting to reduce the dose of medication. This increases the risk of a serious asthma attack.
For more information, see
Using Inhalers
Types of Asthma
COPD
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Please contact us to share your experience or any information which may help others.
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May 2000