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Asthma is a disease that affects the airways (bronchi). In asthma sufferers, the airways become inflamed and produce more secretions. With every breath we take, air flows through the bronchi to the alveoli. The exchange of gases occurs in the alveoli as oxygen flows to the bloodstream to nourish the body and carbon dioxide is expelled from the lungs.
The causes of asthma are not yet fully understood. A family history of asthma and other factors such as allergies are thought to be associated with asthma.
Asthma is an exaggerated response by the airway (bronchi) to foreign substances (allergens) such as dust or pollen, resulting in inflammation. Factors such as smoke, air pollution and respiratory tract infections (cold, flu) can also cause inflammation.
The bronchi are surrounded by a layer of muscle. These muscles, which become more sensitive when the bronchi are inflamed, react by narrowing or constricting – this is known as bronchospasm. Exposure to very cold air, strong odours, exercise, emotional stress and anxiety are all factors that can cause this type of muscle contraction.
Bronchial inflammation and bronchospasm obstruct the flow of air, causing the following symptoms:
The intensity of asthma symptoms varies from person to person and can vary over time as well. Asthma detected in children often resolves by adolescence.
To properly diagnose asthma, your doctor will conduct a medical examination and will ask questions to gain a better understanding of your symptoms. To confirm the diagnosis, the doctor may also use other diagnostic techniques such as measuring the maximum speed at which you can exhale air (peak expiratory flow – PEF), maximum expiratory volume per second or FEV1 (spirometry) and methacholine and histamine challenge tests which measure the degree of responsiveness of the airways.
Complimentary tests, including skin allergy testing, blood tests and chest x-rays, may also be ordered.
Most asthma treatments focus on the two most prominent components of the disease, namely inflammation and bronchoconstriction (narrowing of the airways due to constriction of the surrounding muscles). Inhaled corticosteroids are considered to be the foundation of asthma therapy. They are commonly referred to as “CONTROLLER” medication. They are used on a regular basis and in addition to helping prevent asthma symptoms, they prevent symptoms from worsening and reduce hospitalizations and deaths. Acute asthma attacks may require the use of a systemic corticosteroid (ex. prednisone). This type of medication is taken by mouth and travels throughout the body.
Inhaled bronchodilators work by relaxing the muscles in the bronchial tubes. There are two types of bronchodilators: short-acting and long-acting.
Short-acting bronchodilators are used only as needed to treat asthma attacks and to prevent exercise-induced asthma. They are commonly referred to as “RESCUE” or “RELIEVER” medications since they are used to treat sudden asthma symptoms. They are quick acting and their effect is short-lived. Using this type of medication more than 3 times a week, notwithstanding a daily dose before intense physical activity, is indicative of improperly managed asthma.
Long-acting bronchodilators are used on a regular basis. They should be used in combination with an inhaled corticosteroid. Symbicort® and Advair® are inhalers that combine a long-acting bronchodilator and a corticosteroid. Medications such as theophylline (TheoDur®, Uniphyl®) and leucotriene antagonists (Accolate®, Singulair®) can also be added to treatment. They are used as adjunct therapy in combination with other medications.
Dose adjustments can be made in compliance with the action plan established with your doctor, based on close monitoring of symptoms and the frequent measurement of peak expiratory flow (see the handout on ACTION PLAN FOR PERSONS WITH ASTHMA and the handout on PEAK EXPIRATORY FLOW AND PEAK FLOW METER published by Vigilance Santé).
Ensuring a proper inhaling technique is important as it will provide better efficacy. Your pharmacist can show you how to obtain the best results. He or she may also recommend the use of a spacer and metered dose inhaler, making it easier for you to take your medication.
The key to preventing asthma attacks is to avoid your asthma triggers:
Canadian Lung Association
Allergy / Asthma Information Association