Definition:  

Asthma is a chronic inflammatory disorder of the airway that is characterized by

• Clinically by recurrent episodes of wheezing breathless chest tightness and cough particularly at night or early morning
• physiologically by widespread reversible narrowing of the bronchial airways and a marked increase in bronchial responsiveness

According to CDC more than 25 million Americans, including 6.8 million children under age 18 suffer from asthma

Asthma is associated with mast cell eosinophils and lymphocytes mast cell are the allergy-causing cell that releases chemical like histamine  is the substance that causes nasal stiffness and dripping in the cold and hay fever constriction of airways in asthma and itchy area in the skin allergy eosinophils are the type of white blood cell-associated  with allergy disease T lymphocytes are also white blood cell associated with allergy and inflammation.

Classification :

• Atopic /extrinsic /allergic (70%)
  • IgE mediated immune response  to environmental antigens
• Non-atopic /intrinsic /non-allergic
  • Triggered by non-immune stimuli patient have a negative skin test to common inhaled allergens and normal serum contraction of IgEasthma may be triggered by aspirin pulmonary infection, cold stress, or inhaled  irritants

Precipitating factor

• Allergens
• Cold air
• Virus infection
• Drug
• Exercise
• Food
• Air pollutants
• Physical factor
• Stress
• Occupational factor
• GERD (gastroesophageal reflux  disordered )

Pathophysiology of Bronchial Asthma

Precipitating factor

            ↓

inflammatory cell

• Mast cell
• Eosinophils
• TH2 cell
• Basophils                     MEDIATION                  EFFECTS
• Neutrophils       →   Histamine          →           Bronchospasm
• Platelets                     Lukotriness                      Plasma exudations

Cytokines                          Mucus secretion

Chemokines                     AHR- Airway hyperresponsiveness

Structural Changes

Structural cell

• Epithelial cell
• Smooth muscle cell
• Endothelial cell nerve

Summary of Pathophysiology of Bronchial Asthma

Clinical presentation :

• Wheezing, dyspnea, and cough (variable – both spontaneously and with therapy
• Sputum worse at night or early morning
• Limitation of  activity
• Mucoid Sputum

Sign:

• Increase respiratory rate with the use of accessory  muscle
• Hyper resonant percussion note
• Expiratory wheeze, expiration, is longer than Inspiration
• During very severe attacks  airflow may be insufficient to produce wheeze (silent chest )
• No finding when asthma is under control of under control

Investigation :

• Pulmonary function test -spirometry
  • Estimate degree of obstruction
  • >12% increase in FEV1, 15 minutes after  B2 antagonist inhalation
• Chest x-ray hyperinflation,pneumothorax , emphysema
• Arterial blood gas analysis- hypoxia and hypocarbia
  • Severe acute asthma -hypocarbia
• Skin hypersensitivity test
• Sputum examination
• Complete blood count eosinophils
• Elevated serum IgE level

Management of Bronchial Asthma:

Patients educations

• Avoidance of  precipitating factor
  • Avoid allergens
  • Avoid pollutants
  • Avoid drugs

Drug therapy

• Bronchodilator
  • Beta2 antagonist
  • Anticolingegcis
  • Methylxanthines
• Antiinflammatory
  • Corticosteroid, mast cell stabilizer, and leukotriene antagonist
• Inhaled corticosteroid
  • Use of beta 2 agonists more than two times a week indicate the need for ICS
  • Beclomethasone
  • Budesonide
  • Fluticasone
  • Triamcinolone
• Leukotrienes antagonist
  • Sodium cromoglycate

Classification of Bronchial Asthma

The severity of Bronchial Asthma can be classified according to the Global Initiative for Asthma – GINA severity grade as following:

Stepwise Approach to Asthma:

We can do a stepwise approach to treat bronchial asthma as shown in the chart below.

Status  asthmaticus:

• K/a severe acute asthma
• Severe airway obstructions
• Symptoms persist despite initial standard acute asthma therapy
• Severe dyspnea unproductive cough
• Patient updates upright position fixing shoulder griddle to assist accessory muscle of respiration
• Sweating control  cyanosis tachycardia

Management of Status Asthmaticus:

• High concentration of oxygen through a facemask
• Ipratropium + salbutamol + NS in the ratio of 1:1:2 nebulized in the oxygen who don’t respond within 15-30 minute
• Inj. hydrocortisone 200 mg iv stat followed by 100 mg iv TDS
• Iv antibiotics -board spectrum
• monitor ABG
• Iv fluid – k supplementation may be required
• ET incubations and mechanical ventilation if the above treatment fails.

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Reference: WHO