What is asthma?

Asthma is a disease of the large airways in the lungs. These airways are called bronchi. In asthma, the bronchi have the tendency to become blocked and, as a result, to prevent air from flowing freely in and out of the lungs. This blockage is caused a combination of changes that occur within the bronchi. First of all, muscle around the bronchi can constrict and narrow the bronchi. This process is called bronchospasm. Secondly, the inner lining of the bronchi can swell and, as a result, will also narrow the bronchi. In addition, excessive mucous can be produced within the bronchi, which also contributes to occluding the airway. The swelling and the excessive mucous production are part of a process called inflammation.

Another very common feature of asthma is its reversibility. This means that the bronchospasm and the inflammation can disappear either spontaneously or after treatment. However, this also means that both the bronchospasm and the inflammation can recur. Unfortunately, in some patients, these changes are not completely reversible.

What are the symptoms of asthma?

The typical symptoms of asthma are wheezing, shortness of breath, and cough. Wheezing is a whistling sound that occurs during exhalation (breathing out). It is caused by the narrowing of the bronchi. This narrowing makes breathing more difficult, like breathing through a straw. As a result, a person with asthma can have shortness of breath. These symptoms are often accompanied by cough.

All of these symptoms are usually worse at night than during the day.

What makes asthma worse?

A number of triggers have been identified that can make asthma worse.

In young children, the most common trigger is an upper respiratory infection such as the common cold. Other triggers include exercise, cigarette smoke and environmental allergies such as allergy to pollens, dust mites, and animals. The most common animal to be associated with allergic asthma appears to be the cat.

In a patient with asthma who is taking medications on a daily basis to keep the asthma under control, decreasing or stopping these medications may lead to worsening symptoms of asthma.

Other triggers include barometric changes (weather changes), and cold air.

How can asthma be controlled?

1. Prevention
   The first and most important approach to controlling asthma is to try to identify possible triggers, and to eliminate them if possible.
    
   Exposure to cigarette smoke is, by far, the most important trigger to eliminate as it can contribute to the development of chronic asthma and more permanent damage to the lungs. A useful general rule to follow is that if it smells like cigarette smoke, then cigarette smoke is present even if no one has smoked in the area for hours or days. This means that a parent who smokes should never smoke in any environment where the asthmatic child might be present, such as the home and the family car. In addition, a person who has smoked recently will have cigarette smoke on his/her breath for some time afterwards. Simply having a conversation with someone who has recently smoked can trigger symptoms of asthma. As well, cigarette smoke tends to linger on the smoker's clothing and can also contribute to worsening of asthma symptoms.
    
   There is also mounting evidence that indicates that smoking cigarettes during pregnancy can lead to the development of asthma in the baby.
    
   The next most preventable trigger is exposure to environmental allergies. A person with asthma who is also allergic to an animal, such as a cat, should avoid contact with that animal. This usually means removing the animal from the home. It is not always obvious that contact with that animal is making the asthma worse. Frequently, a person with asthma may be having few symptoms of asthma as long as he/she continues to take asthma medications to keep it under control. However, if that person has a pet to which he/she is allergic, removing that animal from the home may result in being able to reduce the dose of asthma medications needed. In addition, the continued presence of the animal in the home may result in a gradual increase in the dose of asthma medications needed and worse control of the asthma over time.
    
   These same arguments are true with other forms of environmental allergies.
    
   Finally, preventing respiratory infections can greatly influence how well asthma is controlled. It is highly recommended for any person with lung disease, such as asthma, to receive the influenza vaccine. In order to prevent other forms of respiratory infections, frequent hand washing is very effective in reducing the number of infections that one can develop.
    
   Realistically, it is almost impossible to prevent young children, particularly toddlers, from catching the common cold from their playmates or from the general population in public spaces. By nature, toddlers put everything into their mouths! However, among children who have significant problems with asthma despite regular use of asthma medications, it may become necessary to remove them from environments, such as daycare, where they are in contact with numerous other children.
    
   Although exercise is a known trigger of asthma symptoms, it is generally not recommended to avoid exercise as long as the asthma is being appropriately treated. If a child is unable to participate in sports because of asthma symptoms, then the asthma must be treated in order for him to be able to participate sports normally. Restricting exercise is not generally recommended.
    
2. Medications
   There are two main categories of medications available to treat asthma. The first category is bronchodilators. The most commonly used bronchodilator is albuterol. Bronchodilators open up the bronchi rapidly by relaxing the muscles that have tightened up around the bronchi during an asthma exacerbation. This allows air to flow more normally through the bronchi. The effect of the bronchodilators can last up to 4 hours. They help to rapidly relieve shortness of breath, wheezing and even cough. However, once the effect of the bronchodilator has worn off, the muscle around the bronchi can contract again and tighten, making the airways narrow again. The inflammation which is causing the swelling and excessive mucus production within the bronchi is still present. This is what is contributing to ongoing bronchospasm or the contraction of muscles around bronchi.
    
   The second category of medications is anti-inflammatory agents. These agents target the inflammation, and help to decrease the swelling and excessive mucus production. Once this inflammation is under control, the bronchospasm is much less likely to recur.
    
   There are two forms of anti-inflammatory agents. The most effective agents are corticosteroids, which we can refer to simply as steroids. Steroids have been used for decades to treat a multitude of diseases caused by inflammation, including asthma.This is the most effective treatment known to date. Unfortunately, with long-term use, systemic steroids can lead to serious side effects. To treat acute asthma attacks, systemic steroids are used, either in oral form as a pill or liquid, or in the intravenous form, because they can act rapidly. However, for less severe symptoms and to prevent asthma attacks, the preferred treatment is with inhaled steroids, such as budesonide (Pulmicort) and fluticasone (Flovent). These allow for long term use of steroids with very few side-effects. Most patients can be treated with doses of inhaled steroids which are not associated with side-effects. These doses can be given on a daily basis for years without difficulty. It is important to note that in order for inhaled steroids to be effective, they must be given on a daily basis without interruption. The goal is prevention of all symptoms of asthma.
    
   The second form of anti-inflammatory agents used in treating asthma are leukotriene antagonists, such as montelukast (Singulair). These agents appear to be somewhat less effective that inhaled steroids are, but can be very useful. They appear to play a greater role in treating asthma which is triggered by allergies. As with the use of inhaled steroids, leukotriene antagonists are only effective when used on a daily basis without interruption. As with inhaled steroids, the goal is prevention of all symptoms of asthma.
    
   The usual treatment plan includes both an anti-inflammatory agent and a bronchodilator. The anti-inflammatory agent is used daily. The bronchodilator should always be available in order to treat sudden onset of symptoms such as wheezing, shortness of breath or cough. A useful rule of thumb, to help determine whether the asthma is being well controlled or not, is to keep track of the frequency with which the bronchodilator is being used. If the bronchodilator is being used more frequently than usual, this is a good indication that the asthma may be out of control. This often means that the dose or the type of anti-inflammatory agent needs to be changed. Therefore, the physician should be contacted.
    
3. Evaluation of asthma
   Regular follow-up with a physician is extremely important in maintaining adequate control of asthma. For older children, it is very useful to perform pulmonary function testing. These tests consist of blowing into a machine which measures the amount of air exhaled, and the speed with which the air is exhaled.
    
   For the physician, the single most important method of evaluating a patient's long-term control of asthma is the taking of a history from the patient. This consists of identifying symptoms, their duration and frequency, and recording the patient's use of medications.

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