Asthma

It's a biggie but a goodie! Asthma is a disease which is common in both children and adults. You need to know about it, how to manage it, how to diagnose it and how to explain Einstein's Special Theory Of Relativity. OK, you don't need to the last of these but it might help...I'll get on with it shall I.

Definition

Chronic, episodic inflammation of the airways caused by hypersensitive reaction to an allergen.

Epidemiology

According to Asthma UK, 5.2 million people, including 1.1 million children in the UK suffer from Asthma. Hence, it is a very important disease.

Pathophysiology

Books have been devoted to describing the pathophysiology of asthma. Put very simply, it's an immune response causing your airways to constrict and inflame. Foreign bodies (stimuli/allergens/crap are all valid terms) such as dust, pollen, smoke... enter the airways. In most people, this causes no problems. Asthmatics however, are hypersensitive and so their bodies mount an immune response. This causes the release of IgE antibodies.

This is important in understanding the bronchoconstriction (the "constrict" bit from above). Smooth muscle (which surrounds airways) have Beta-2 receptors which, when blocked, result in the smooth muscle to constrict. "So they get blocked but what does the blocking, Mr Chowdhury?", I hear you say. Well, this is where IgE comes into it. It blocks it.

The bronchial inflammation (the "inflame" bit from above) is also an immune response. Inflammation is a non-specific defence mechanism of the body and it's no different in the lungs. Except for the whole, blocking the airway and potentially killing you thing. But the biochemistry is pretty much the same (not that I remember it).

Risk Factors

Basically, it comes down to: atopy which are conditions like eczema or hayfever based on that old chestnut, hypersensitivity; family history of asthma or any atopic conditions; being a boy; external factors like smoking, pets, house dust mites etc.

Clinical Features

There are basically four:

• Shortness of breath
• Wheeze
• Chest tightness
• Cough, usually worse at night.

Pretty easy, huh. The shortness of breath comes in episodes accompanied by the chest tightness.