Asthma: Epidemiology, Classification, Causes, Pathogenesis, Morphological changes of airway, Signs and Symptoms, Investigations, Treatment/Management, Asthma in pregnancy and Prognosis of Asthma

Asthma is a common chronic inflammatory condition of the airway which is classically characterized by:

Asthma most frequently occurs between
the ages of 3-5 years

1. Airflow limitation which is usually reversible spontaneously or with treatment.
2. Airway hyper-responsiveness to a wide range of stimuli which would cause no ill effects in the normal airways of nonasthmatic individuals.
3. Inflammation of the bronchi/airway with T lymphocytes, mast cells, eosinophils with associated plasma exudation, oedema, smooth muscle hypertrophy, matrix deposition, mucus plugging and epithelial damage.

What happens during an asthma attack?

The underlying genetic basis for hyper-responsive airways is not entirely clear, although significant advances have been made in understanding the pathogenesis and environmental triggers of asthma "attack." In some cases, the attacks are triggered by exposure to an allergen to which the person has been previously sensitized, but often no trigger can be identified.

Typical symptoms of asthma include wheeze (high pitched musical sound), cough, chest tightness and dyspnoea (breathlessness) particularly at night and/or early in the morning.

In chronic asthma, inflammation may be accompanied by irreversible airflow limitation as a result of airway wall remodelling that may involve large and small airways and mucus impaction.