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Bronchial asthma: Pathophysiology, Clinical features, Management

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Bronchial asthma is a chronic inflammatory condition of the respiratory tract characterized by episodic exacerbations of hyperresponsiveness and reversible airway obstruction.


The early phase of bronchial asthma occurs within 15-30 minutes and is marked by bronchoconstriction, primarily due to the release of histamine, leukotrienes, and bradykinin. The late phase occurs after 4-12 hours and is characterized by airway inflammation and increased secretion.

bronchial asthma

Asthma triggers

Asthma triggers encompass a variety of factors:

  • Allergens: including house dust mites, mold, pollen, and certain drugs.
  • Environmental factors: such as smoke, dust, strong odors/fumes, and exposure to cold air.
  • Physical activity.
  • Emotional triggers.

Clinical features


  • Intermittent dry cough, recurrent or nocturnal episodic cough
  • Wheezing (in acute exacerbation or advanced asthma)
  • Breathlessness or shortness of breath
  • Chest tightness (only expressed by older children)
  • Nonspecific
    • Fatigue
    • Exercise intolerance.
    • Poor sleep

General examination

  • Dyspneic
  • Prominent accessory muscles of respiration
  • Air hunger, cyanosis
  • Flaring of alae nasi
  • Altered sensorium in acute exacerbations.

Examination of chest

  • Inspection: Tachypnea, chest hyperinflated, presence of subcostal, suprasternal, and intercostal recessions
  • Palpation: Reduced chest expansion but central trachea
  • Percussion: hyper-resonant
  • Auscultation: Vesicular breath sound with prolonged expiration, rhonchi present.

Differential Diagnosis

  • Bronchiolitis
  • GERD
  • Hypersensitivity pneumonitis
  • Foreign Body inhalation
  • Cystic fibrosis


Generally, diagnosis is based on clinical, but laboratory support has little role.

Clinical evidence

  • Presenting complaints like recurrent cough, breathlessness, wheezing, etc.
  • History of asthma

Laboratory Investigation

  • PEFR: Morning-evening variation>20%
  • Low FEV1
  • FEV1/FVC<0.8
  • Bronchodilator response (beta agonist): Improvement in FEV1≥12%
  • Exercise challenge: Worsening in FEV1 ≥ 15%
  • Chest X-ray: hyperinflation of lungs (low flat diaphragm and more horizontal ribs) and tubular heart
  • Absolute Eosinophil Count (AEC) test: may be increased.
  • Allergy test but limited role



  • Maintain normal activity.
  • Prevent sleep disturbance.
  • Prevent chronic asthma symptoms.
  • Prevent severe exacerbation.
  • Less or No side effects from drug therapy


  • Beta 2 agonist (inhaled): salbutamol, terbutaline
  • Inhaled anticholinergics: Ipratropium bromide
  • Short course systemic steroid: oral prednisolone, Methyl prednisolone.

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