Asthma is a chronic inflammatory obstructive lung disease characterized by:
1. Airway obstruction that is reversible either spontaneously or with treatment
2. Airway inflammation.
3. Increased airway responsiveness to a variety of stimuli.
Stimulus could be: physical, chemical, immunological, pharmacological or pathological (ex: Allergens, viral infection, cold air, dry air, smoke, pollutants, methacholine).
Asthma has two phases: Early Phase
Early phase: immediate and spontaneous bronchoconstriction after inhaling a specific allergen. This phase improves over an hour is reversed easily by inhalation of bronchodilators.
Late phase: occurs 4-12 hours later, more severe and prolonged, difficult to reverse with bronchodilators. Inflammation is a key factor here.
Why are we interested in these phases?
Knowing these phases helps determine what drug we need, for example:
Cromolyn blocks both phases.
Bronchodilators (B2-agonists) blocks early phase.
Corticosteroids blocks late phase.
Expiratory wheezing, dyspnea and coughing.
Chest pain (due to the abnormal utilization of accessory muscles of respiration).
Atelectasis (collapse of pulmonary alveoli or of a segment of the lung).
Asthma could be mild, moderate or severe according to the frequency of symptoms. (See table)
Goals of therapy:
1. Maintain normal activity levels including exercise.
2. Maintain near normal pulmonary function rates.
3. Prevent chronic and troublesome symptoms (nocturnal symptoms, exacerbation on exercise).
4. Prevent recurrent exacerbation of asthma.
5. Avoid adverse effect from asthma medications.
How can we achieve such goals?
By a complex procedure including patient education, environmental control, comprehensive pharmacologic therapy, and objective monitoring measures.
Remember: the most common cause of death from asthma is under treatment....