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Asthma is a chronic respiratory condition where the airway is inflamed and narrowed causing breathlessness, wheezing, chest tightness and coughing. Symptoms come as recurrent episodes called asthmatic attacks more commonly during the night and early morning. Asthma is usually diagnosed in childhood and lasts for life.
Anatomy of asthma
Our lungs consist of millions of air tubes or airways (bronchi and smaller bronchioles) bringing air in and out of the body. Each tube ends with a cluster of air sacs (alveolus, plural alveoli) where the gas exchange process takes place. The airways have a layer of smooth muscle in their wall which enables them to constrict or dilate. In response to the body’s higher demand of air, such as during exercise, the airways dilate to increase air flow. In response to presence of pollutants in the air, they constrict to prevent the lungs from being polluted. In people suffering from asthma these airways are inflamed, narrowed and become more sensitive to certain substances. Asthmatic attack (or exacerbation) happens when the airways react to these substances. During the attack smooth muscle contracts squeezing the airways making them even narrower, mucus secretion increases further obstructs the airways.
Causes of asthma
Causes of asthma are complex and not fully understood but likely involve a combination of genetic and environmental factors. Family history is a known risk factor for asthma. There are at least over twenty genes associated with asthma of which many are involved in the immune system. Most people who have asthma also have allergies. Many environmental factors such as air pollution, chemicals, smoking, allergens have been associated with development of asthma or triggering of asthmatic attacks.
Triggers of asthmatic attack
Triggers are factors that initiate the attack, these can be very different from person to person. Common triggers include :
– allergens (pollen, animal fur, pet dander, sulfites in preserved food..)
– irritants (cigarette smoke, industrial chemicals, dust, household chemicals,..)
– some medication (aspirin, beta blockers,..).
– physical activity, exercise.
Treatments
There is no cure for asthma. The most effective way to manage symptoms is to identify the triggers of asthmatic attack and avoid them.
There are two main classes of medication:
– bronchodilators – substances that dilate bronchi and bronchioles – are used as short-term relief of symptoms.
– inflammation moderators such as corticosteroids are used as long-term treatment.
Asthma inhalers are used to deliver medication to the lungs.
Associated conditions
A number of conditions tend to occur more frequently in people with asthma:
– Allergies : eczema and hay fever. These individuals are considered hyperallergic (high tendency to develop allergic reactions). The combination of these conditions is called atopy or atopic symdrome.
– Gastroesophageal reflux disease (GERD): a condition in which stomach acid backs up and damages the mucosal lining of the esophagus. GERD may worsen asthma symptoms and medications for asthma often worsen GERD symptoms. Treating GERD usually improves asthma and must be included in asthma treatment plan.
– Obstructive sleep apnea (OSA): asthmatic patients tend to develop OSA. The mechanism is not fully understood but it’s likely due to nasal obstruction. Click on the link to read more about OSA.
– Sinusitis: inflammation of paranasal sinuses. Sinusitis commonly worsens asthma symptoms and makes treatment less effective.
