ASTHMA
Asthma is a chronic inflammatory disorder of the airways associated with variable (usually reversible) airflow obstruction and enhanced bronchial hyper responsiveness to a variety of stimuli.
Causes
Asthma is characterized by excessive sensitivity of the lungs to various stimuli. There is increasing evidence to suggest genetics play an important role in the etiology of the disease. Apparently, environmental factors interact with inherited factors to increase the risk of asthma. Environmental triggers range from viral infections and allergies, to irritating gases and particles in the air. Each person reacts differently to the factors that may trigger asthma. Physiological factors that may trigger or increase asthma symptoms include:
• Viral upper respiratory infections.
• Heavy exercise.
• Untreated conditions such as rhinitis, sinusitis, and gastroesophageal reflux (GERD).
• Drugs: NSAIDS such as aspirin.
• Ibuprofen, acetaminophen, naproxen sodium and Ketoprophen; statin drugs (cholesterol reducing medications) and other anti- inflammatory drugs.
• Menstrual cycle/hormone changes.
Food Allergy:
Food allergies involve the body’s immune system reacting to proteins found in food. The body treats these proteins the same way as it would be a disease. Different people react to different types of food although some types have a greater chance of becoming a trigger.Based upon causes, the asthma is divided into two types:
a. Intrinsic asthma: Usually develop beyond age 40 and have many causes other than exposure to allergens.
b. Extrinsic asthma: Most commonly develop in childhood and caused by exposure to definite allergens.
Classification of Asthma
Current classification of asthma is based on clinical severity. This allows asthma sufferers and clinicians to better manage treatment choices and clinical outcomes.
1. Mild Intermittent Asthma: It occurs in people with daytime symptoms that occur no more frequently than twice a week and night-time symptoms that occur no more than twice a month.
2. Mild Persistent Asthma: It is characterized by daytime symptoms that occur more than twice a week but less than once a day with night-time symptoms more frequent than twice a month. These people are asymptomatic but have abnormal pulmonary function tests. Exacerbations begin to limit their activity.
3. Moderate Persistent Asthma: It occurs in people who have daytime symptoms every day and night-time symptoms more than once a week.
4. Severe Persistent Asthma: It is characterized by continual daytime symptoms and frequent night-time symptoms. They experience limited physical activity and exacerbations are frequent.
Pathophysiology
The various common allergens are pollens, dust, mites, some food material and certain drugs which precipitate the asthmatic attack. The allergens upon exposure stimulate production of IgE which further bind to mast cells. Upon re-exposure to same allergen, the said allergens readily bind to IgE and result in degranulation of mast cell to release certain inflammatory mediators such as histamine, leukotriens, prostaglandins etc. With exposure to a trigger, a cascade of cellular responses cause:
1. Increased production of thick tenacious mucus with impaired mucocilary function.
2. Mucosal swelling due to increased vascular permeability and vascular congestion. 3. Bronchial smooth muscle contraction
4. These changes cause bronchial hyper responsiveness and obstruction. Airway obstruction increases resistance to air flow and decreases flow rates, including expiratory flow.
6. Untreated inflammation can cause long term airway damage that is irreversible (airway remodelling).
Symptoms
• Coughing, especially at night, during exercise or when laughing.
• Shortness of breath. • Chest tightness.
• Wheezing (a whistling or squeaky sound in chest when breathe, especially while exhaling).
• Any asthma symptom is serious and can become deadly if left untreated.
• Symptoms may be triggered by exposure to an allergen (such as ragweed, pollen and pet hair or dust mites), irritants in the air (such as smoke, chemical fumes or strong odours) or extreme weather conditions.
Prevention and Treatment
Prevention of exposure to known triggers is warranted. Hyposensitization may be beneficial if the asthma has an allergic mechanism, in such cases:
• Identify and avoid asthma triggers.
• Identify and treat attacks early and monitor breathing.
• Other measures include dust free house.
• Intake of selective type of food.
• Avoid exposure to extreme cold condition.
• Get vaccinated for influenza and pneumonia.