Written by DrShailesh Doshi

Bronchial Asthma

Bronchial Asthma is defined as a disease of airways characterized by increased responsiveness of tracheobronchial tree to some stimuli. It is usually present as episodes of breathlessness, chest tightness, wheezing resulting from narrowing of airways by a combination of muscle spasm, mucosal swelling and viscid bronchial secretion.

Types of Bronchial Asthma

1. Allergic Type :- Early onset or Extrinsic type
• starts in childhood or early adult life
• seasonal
• more common in males
• mainly due to hypersensitivity to allergens
• persons are prone to develop IgE antibodies
• patients also suffer from other allergic disorders like allergic rhinitis, eczema etc.
• there is family history of similar disorder
2. Non Allergic Type :- Late onset or Intrinsic type
• develops later in adult life
• external allergens play no part in its pathogenesis
• no personal or family history of allergic disorder

Causes

The stimuli that increase airway responsiveness and precipitate acute episodes of asthma are grouped into seven categories.

Allergens	Pharmacological Causes
Environmental Causes	Occupational Causes
Infectious Causes	Exercise related
Emotional Factors

1. Allergens

Most of the allergens that provoke allergic asthma are airborne and are derived from pollen, mite containing house dust, feathers, animal dander, fungal spores etc. Exposure of susceptible individuals to allergens, leads to production of IgE antibodies. Subsequent exposure to the same allergen leads to antigen-antibody reaction causing release of pharmacologically active substances like histamine, bradikinin etc producing intense inflammatory reaction with broncho constriction, vascular congestion and edema formation, increased mucus production.

2. Pharmacologic Stimuli

The drugs commonly inducing acute asthma are aspirin, coloring agent tartarazene, B-blockers. Aspirin induced asthma is insidious, beginning with rhinitis followed by sinusitis and progressive asthma. Subsequent exposure in small doses precipitates acute and severe bronchospasms.

3. Environment and Air Pollution

Asthma tends to develop in heavy industrial & densely populated urban areas where there is high concentration of atmospheric pollutents and allergens. Cold air, tobacco, smoke, dust and acid fumes are precipitating factors.

4. Occupational Factors

Asthma has been reported to follow exposure to industrial compounds like metals, salts, wood and vegetable dusts, pharmaceutical agents, plastics, animal and insect dusts, serums, secretions.

5. Infections

Respiratory infections, especially viral infection, commonly evoke acute exacerbation of asthma. Inflammatory changes in airway mucosa following a viral infection increases its responsiveness to non specific stimuli.

6. Exercise

In children and young adults, during exercises causes thermal changes within the airway as heat and water are transferred from mucosa to inspired air making it colder and drier precipitating asthma.

7. Emotional Stress

Psychological factors worsen or ameliorate the disease process.

Pathology

• Bronchi shows numerous gelatinous plugs of exudate
• Lungs are overdistended and fail to collapse when pleural cavities are opened
• Histopathological study shows
  • Hypertrophy of bronchial smooth muscles
  • Mucosal edema

Signs and symptoms

The symptoms are

• Dyspnoea, cough and wheezing.
• Typically it is an episodic disease. Attacks often occurs at night.
• Attacks may follow exposure to a specific allergen, physical exertion, viral respiratory infection or emotional excitement.
• At the onset, patient feels a sense of constriction in the chest with a dry cough.
• Respirations become audibly harsh and wheezing during inspiration as well as expiration become prominent.

Chronic asthma

• Symptoms of chest tightness, wheeze, breathlessness on exertion, spontaneous cough and wheeze during the night.
• Cough productive of mucoid sputum with recurrent episodes of frank respiratory infection is common.

Severe Acute Asthma (Status Asthmaticus)

• Life threatening attacks of asthma.
• Patient adopts an upright posture to assist the accessory muscles of respiration.
• There is dry cough which aggravates the respiratory distress.
• In addition there are rapid pulsation, sweating central cynosis etc.

Investigations

• Chest X-Ray
• Pulmonary Function Test
• Skin Hypersensitivity Test

General measures

• Avoidance of allergens:-
Measures should be taken to reduce exposure to the allergen identified as producing asthma.
• Complete bed rest in comfortable position.
• Avoid eating oily and spicy food as it aggravates the cough
• Drink warm water to feel better