Asthma

Asthma

Normal airway with relaxed muscles.

Constricted airway in allergic reaction, with muscles around the airway contracting.

	With exposure to particular allergens or predisposing factors, asthma patients experience difficulty in breathing due to obstruction in the airways. The causes of air flow obstruction in asthma include:

		Swelling of the airways
		Excessive mucus production
		Inflammation of the airways
		Contraction of the airway smooth muscles that closes the airway

	People with asthma have to breathe at the top of their lungs, which is exhausting and feels terrible. This is because they trap up to 2 litres of air in their chests. As they breathe in air, they open up their chests and this allows air to move around the airway obstructions. When they try to breathe out the air, these obstructions close, therefore the air is trapped inside the lungs, causing a lot of discomfort.

	Asthma patients should avoid the allergens to which they are sensitive. In addition, they should not smoke. Parents with asthmatic children should also stop smoking. It is recommended that al asthmatics should exercise, though the exercise regime should be carefully planned as some patients have exercise-induced asthma.

What Causes Asthma

The causes of asthma includes allergy, infections, industrial chemical exposures, complications from drugs and chemicals, exercise, vasculitis (inflammatory disease of the blood vessels), and idiopathic causes (i.e. unknown causes).

1. Allergy and Infections

The most common cause of asthma is allergy. It may also be caused by infections such as bronchiolitis., which is a wheezing disease that affects children less than 2 years old and is caused by a viral infection of the airways.

Age of patients with asthma	Percentage with allergies
< 16 years old	90%
< 30 years old	70%
> 30 years old	50%

2. Drugs and chemicals

Common drugs like aspirin cause asthma in 10% of asthmatics.

3. Sulphiting agents (or sulfiting agents)

Sulphiting agents are chemicals added to processed foods to keep them from turning brown due to oxidation. It is another common cause of asthma. Foods with sulphiting agents include dried fruits, fruit / vegetable juices, and wines. These sulphiting agents mix with acids in the stomach and become sulphuric acid, which is a gas. The gas travels up through the oesophagus. Part of it is breathed in, and provokes asthma.

4. Chemical causes

It is estimated that as many as 15% of asthmatics develop asthma in response to industrial exposure to chemical allergens. The most common cause of occupation-related asthma is the inhalation of chemical substances like toluene di-isocyanates, trimellitic anhydrides, and enzymes. On smoggy days, the exhaust from motor vehicles or factories significantly worsens the asthmatic symptoms of sufferers.

5. Exercise

Exercise is a potent cause of asthma. As one exercise, one increases ventilation by taking rapid and shallow breaths. Such hyperventilation cools the airways. A reflex reaction to this cooling of the airways is contraction of the airway smooth muscles, resulting in asthma for certain patients. A proper warm-up period would reduce exercise-induced asthma. Therefore, people with asthma should still have exercise carried out in appropriate ways.