ASTHMA  
  INTRODUCTION  
 
Asthma is a chronic respiratory condition that affects people of all ages.
 
At present there is no known cure, but it can be treated and controlled.
 
It is most common in childhood but is being diagnosed more and more in adults.
 

It affects twice as many boys as girls in childhood; more girls than boys develop asthma as teenagers, and in adulthood, the ratio becomes 1:1 males to females.

  

Asthma affects people in varying degrees, from very mild (only during vigorous exercise) to very severe. Those with severe asthma may have symptoms every day that may cause some lifestyle restriction; in these people symptoms occur more easily and more frequently.

 

There is a general trend of increased deaths and hospitalisations from asthma recorded in all the industrialised countries of the world, Canada included.

 

In Canada about 3 million people are affected, and approximately 20 children and 500 adults die each year from asthma. However, with adequate treatment most deaths from asthma can be prevented.

 
 
  What Is Asthma?  
  Asthma is a chronic lung condition characterised by difficulty in breathing. People with asthma have extra sensitive or hyperresponsive airways. The airways react by narrowing or obstructing when they become irritated. This makes it difficult for the air to move in and out. This narrowing or obstruction can cause one or a combination of the following symptoms:  
 
wheezing  
coughing  
shortness of breath  
chest tightness  
 
  This narrowing or obstruction is caused by:  
 
Airway inflammation (meaning that the airways in the lungs become red, swollen and narrow)  
Bronchoconstriction (meaning that the muscles that encircle the airways tighten or go into spasm)
Airway Inflammation		  
 
  Airway Inflammation  
 

The picture shows the opening of a normal airway on the left. In the centre is a picture of an airway which has been exposed to a certain stimuli (i.e. inhaled allergen like grass pollen). It has become swollen and plugged with mucus, thus making the airway opening considerably smaller, and therefore more restrictive to airflow. The aim of treatment is to reduce this inflammation and prevent further injury to the airway.

 
 
 
  Bronchoconstriction  
 
On the right is a picture of an airway which has been exposed to a certain stimulus (such as cold air or vigorous exercise). The muscle fibres surrounding the airway have contracted, thus making the airway opening considerably smaller. The aim of treatment is to reduce this constriction and prevent further injury to the airway.