Asthma is a chronic condition characterized by frequent bouts of breathlessness. In an asthmatic attack the bronchi become narrowed because their walls contract, and the resulting partial obstruction causes difficulty in breathing, often accompanied by wheezing. The narrowing can occur suddenly, sometimes in a few minutes, and there may also be a slow swelling (oedema) of the mucous membrane lining the bronchi, along with the secretion of a thick and sticky mucus.
A common type of asthmatic attack begins with a feeling of tightness in the chest, sometimes preceded by a dry irritating cough or blocked nose. During an attack, the depth of breathing increases and may reach the maximum level of full inspiration. This stretches the narrowed bronchi so that the necessary amount of air can enter the lungs. Wheezing is caused by the turbulence of the air as it passes through the narrowed air passages. If the attack is severe the sufferer has to devote all his or her energy to the task of breathing, is unable to sleep or eat, and can drink only a little. The symptoms often subside of their own accord: breathing gradually becomes easier, the wheezing declines, and a little sticky colorless sputum may be coughed up.
The development, duration and severity of attacks varies between individuals. The attack may develop in minutes or take hours to reach its peak; it may cause only minor discomfort and breathlessness or may be severe enough to cause total incapacity and require hospitalization. Intervals between attacks can vary from a few days to many months. In anyone person the pattern tends to be consistent, although it may change over several years. Death from an asthmatic attack is rare except in elderly people who have other diseases as well.
There is sometimes no obvious cause of asthma, but in many cases attacks are triggered by an allergic reaction to a substance harmless to most other people. Such substances, called allergens, include airborne panicles such as pollen, house dust and animal fur or feathers. People who have allergies, for example hay fever or eczema, are also more likely to have asthma.
Asthma may occur mainly at home because of house dust, or mainly at work because of dust from occupational materials. Pollen grains and mold spores are often an important source of asthma in a similar way to hay fever. In house dust the main cause is the house mite which feeds principally on tiny scales of human skin shed from the body. The mite is microscopic and occurs in great numbers in the dust on the surfaces of mattresses, and in carpets and soft furnishings. Anything that throws house dust into the air, such as bed-making or cleaning, is likely to bring on an attack of wheezing in an asthmatic sensitive to house dust. These mites thrive in warm, damp conditions, and their numbers increase in August, September and October. Also present in house dust, but less important in causing asthma, are mold spores, algae, bits of feathers, kapok, and horsehair. Dandruff and hair from animals, especially from cats and dogs, are a common cause, and other pets such as rabbits, hamsters, mice and birds may also be allergenic.
Certain foods and drinks can in certain people provoke an asthmatic attack Milk, eggs and wheat may be the cause, particularly in children, and at any age, fish. eggs, chocolate and nuts may be responsible. Although drugs can cause allergic reactions they rarely cause asthma.
A wide range of dusts, gases. vapors and fumes emitted by industrial processes may be responsible for asthma: polyurethane paint sprays, toluene diisocyanate (used in making polyurethane foam), sulphur dioxide, phtalic anhydride (used in PVC production) and platinum salts (used in electroplating) have all been suspected of causing asthma.
Emotional and psychological stresses may also provoke asthmatic attacks in certain people; for example parents may be over-protective or over-ambitious towards their children and this can contribute towards the development of asthma. Physical stress, for example in some forms of exercise, is also a possible triggering factor for asthma.
The first stage of treatment is to find the cause of the asthma, by taking a detailed history of the affected person, which will include information on the environment at home and at work, allergies, chest infections and emotional stresses. Skin tests, which involve applying small amounts of different allergens to the skin by pricking or scratching the surface, may be carried out. It is possible to make up to twenty-five tests on the skin of the arm or the back at one session. If the patient is sensitive to a substance a small reaction, in the form of a weal or flare, will occur at that particular site, thus indicating the cause or causes of the asthma.
Once the allergen has been identified, treatment involves avoiding exposure to it. In any case, most asthmatics are helped if the amount of dust in their house is reduced, by limiting carpets or soft furnishings, and by vacuum-cleaning thoroughly. Any dampness in the structure of the home should also be repaired, so as to reduce the possibility of mold spores in the air. Feathers in pillows and quilts should be replaced by plastic foam. Pets and domestic animals, if shown to be the cause, should be removed. If certain foods, drinks or drugs are the cause of the allergy, it is important to make sure that mixtures containing them are avoided.
There are many drugs available which will prevent attacks occurring or reduce their severity. Bronchodilators, drugs which relax the muscles of the bronchus when it has gone into spasm, can bring relief during an asthmatic attack Drugs which have this effect may be inhaled or swallowed and new types are constantly being developed. Relief is most rapid when the drug in the form of a fine spray is inhaled through the mouth, since this is the fastest way for the drug to reach the lungs. Several types of inhalers are available but if you find them difficult to use (because the release of the spray must coincide with taking a deep breath), devices are available to make this easier. Alternatively, these drugs may be swallowed. For severe, recurrent attacks of asthma there are steroid drugs that help to prevent attacks. These are also usually inhaled. In a particularly severe or life-threatening attack, the drug may be injected.
Where anxiety is a main cause of asthma, tranquillizers may help, and psychotherapy has been used when emotional problems are responsible. In severe cases, hospital treatment with oxygen and mechanical breathing aids may be needed.