• What is Asthma ?
• Symptoms
• Known Causes
• Diagnosis
• Conventional Treatment

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What is Asthma?

Asthma is a very common disease, affecting about one in every forty people, and approximately two thirds develop symptoms in early childhood. It is characterized by narrowing of the airways of the lung (bronchi) due to tension or spasm of the muscles in the bronchial walls. The respiratory tract invariably becomes congested with thick sputum. Many patients have elevated levels of certain types of white cells in the blood, eosinophils, which are characteristic of allergic diseases.

Asthma is often divided into two categories, allergic and nonallergic although most patients have elements of each type. The common factor in all asthmatics is a respiratory system which is overly sensitive to various irritants, and causes the airways to go into spasm.

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Symptoms

The bronchial spasm and mucus plugging which occur in asthma can give rise to a variety of symptoms including wheezing, shortness of breath and coughing . Typically the onset of asthma appears sudden, but as the symptoms progress, they go from a mild nuisance to severe breathlessness, fatigue, and even respiratory failure. Approximately 5,000 people die every year in the U.S.A. from asthma.

The typical progress of symptoms begins with minimal shortness on heavy exertion, mild wheezing and coughing. It then progresses to shortness of breath on lesser degrees of exertion, and finally at rest, mild coughing which usually worsens at night, in cold air, or during exercise. There then follows wheezing and mild shortness of breath at rest, and finally severe suffocating cough and breathlessness at rest. In severe and chronic cases, every ounce of energy is spent in ejecting each breath, and the slightest increase in fatigue or sedation can bring about sudden respiratory failure and death.

Allergies - Some asthma sufferers inherit a tendency to develop sensitivities to various substances in the air, such as pollens, molds, house dust and others. Upon exposure, the sufferer's immune system over- reacts, producing copious amounts of an antibody group called immunoglobulin E, and other complex substances. These substances trigger a series of reactions culminating in the production of internal chemicals with bronchospastic properties which brings about the asthma attack. 

Often, where an allergy is the cause, sufferer's will also tend to have other allergic diseases as well (eg. hay fever and eczema). Allergies can be confirmed by blood tests showing high levels of antibodies, eosinophils (see above), and other allergy-related substances

Exercise & Stress - In many asthmatic sufferers, physical exertion can trigger off an attack. Recent research has shown that rapid loss of heat from the respiratory tract is the culprit and, for this reason, cold air alone may often bring on an attack. Similarly, hyperventilation either from mental/emotional stress or other circumstances often triggers an attack.

Common allergens (substances causing allergies) in asthma include:- 

1. Aspirin and its relatives, the "nonsteroidal" drugs like ibuprofen, indomethacin, naproxen and many others can set off severe attacks in some patients. It is thought that this is due in part to the fact that these drugs interfere with the body chemicals called prostaglandins which have an important controlling effect on the lungs in asthmatic sufferers. All it takes in some children is one aspirin tablet to cause a violent asthmatic attack.
2. Yellow food dye - Tartrazine (yellow 5) is thought to cause asthma in some patients. (NB. This is used in many foods included orange squash, commercial cheeses, yellow and orange sweets and many others processed foods). 
3. Foods (see diet & nutrition section)

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Known causes

Direct causes are those that cause asthma through a direct affect on the airways, rather than by producing antibody reactions as in an allergic reaction. 

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Diagnosis

The patient's history is often sufficient in itself to diagnose asthma in most patients, especially when there is a clear link with seasons, pets, chemicals or other factors. However, characteristic lung findings, blood tests, other data can confirm the diagnosis.

The main examination for the diagnosis is pulmonary function testing. In this test the patient breathes into a special machine which measures air flow. If obstruction is noted, an inhaled bronchial relaxing drug is given and the test repeated. This test is by no means 100% confirmatory as some asthmatics have a normal baseline pulmonary function test (especially where cough is the only symptom). 

However, there are other diseases which produce similar symptoms to asthma including blockage of the upper airways by tumour, scars, thyroid enlargement, congestive heart failure and pneumonia. These must be ruled out by the examining physicia before asthma can be confidently diagnosed. 

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Conventional Treatment

Coventional medical treatment focuses on the symptoms rather than potential causes of asthma patients. Immunotherapy (allergy shots) is controversial in asthma treatment as there is little scientific proof of its value.

Drugs are commonly prescribed and there has been a trend in recent years to rely on inhaled agents, which offer increased benefit with fewer side effects than oral or intravenous therapy. 

Common inhalers include Salbutamol and metaproterenol (direct bronchial dilators), cromolyn (blocks allergy-related chemicals from being released in the lung), and beclomethasone (a cortisone -like drug which reduces inflammation and allergic manifestations) but there are side effects associated with these drugs which include tachycardia, hypertension and headaches.(2) 

Oral drugs include theophylline, which dilates bronchial passages but side effects from this drug are common and include nausea, gastro-intestinal disturbances, insomnia, tachycardia and even convulsion.(3) 

Cortisone and prednisone are steroid drugs which are very effective in asthma but they too can produce side effects including decreased resistance to infection, dependence on the drug, stomach problems, osteoporosis, cataracts, and others. (4) 


(1) Impact on Human health & Air Pollution in Europe , World Health Organisation July 1990
(2) British National Formulary
(3) British National Formulary
(4) British National Formulary