Bronchial Asthma Etiology Pathogenesis Clinical features Treatment of Bronchial Asthma

Bronchial Asthma Etiology Pathogenesis Clinical features Treatment of Bronchial Asthma

  • Asthma is a chronic inflammatory disease of air­ways characterized by increased bronchial re­sponses to a variety of stimuli.
  • There is widespread narrowing of air passages which is relieved by therapy, or by itself.
  • The typical clinical picture is paroxysms of dyspnoea, cough; and wheezing.
  • Most attacks are short-lived, for minutes to hours and patient recovers completely after an attack.
  • The attack comes in episodes lasting for minutes, hours, days or weeks.
  • There are symptom-free periods between attacks.
  • Status asthmaticus severe obstruction persist­ing for days or weeks continuously.
  • Serious attacks can result in death ,
  • Age: Usually occurs before age of 10 years or before 40 years age.
  • Sex: Amongst children, it is more common in males.

Bronchial Asthma 1

Bronchial Asthma Etiology Pathogenesis Clinical features Treatment of Bronchial Asthma

 

History

  • Symptoms of recurrent episodes of airway obstruction or airway hyper-responsiveness may include:
  • Cough (particularly if worse at night)
  • Wheeze
  • Airflow obstruction is at least partially reversible.
  • Alternative diagnoses are excluded.
  • Chest tightness
  • Difficulty breathing
  • Symptoms are typically precipitated or worsened by exercise, viral infections, irritants such as allergens, changes in weather, stress or strong emotions, and/or menstrual cycles.

Bronchial Asthma Etiology

  • It is an atopic disease (genetic) where environ­mental factors have an important role.
  • Allergic asthma is associated with rhinitis, urti-­caria, eczema, increased IgE, and positive reac­tion to intradermal antigens.
  • Some patients have non-atopic asthma (no his­tory of allergy) or idiosyncratic asthma.
  • Asthma of early life usually has allergic basis. Asthma occurring in later life usually has no his­tory of allergy.

Bronchial Asthma Pathogenesis

  • The airways are inflamed, edematous, infiltrated with eosinophils, neutrophils, Iymphocytes.
  • The cells involved in inflammatory and allergic response are masked cells, eosinophils, Iympho­cytes, epithelial lining cells of airways .
  • The IgE response is controlled by T and B Iym­phocytes in allergic asthma.
Stimuli that can cause asthma
  • Allergenic
  •  Drugs
  •  Environmental factors
  •  Occupational factors
  • Infections
  • Exercise
  • Emotions.
Drugs which can cause asthma
  • Aspirin
  • Tartrazine – colouring agent .Y Beta adrenergic antagonists y Indomethacin
  • Ibuprofen
  • Inhalational bronchodilator solutions .v’ IV glucocorticoids.

Pathophysiology Bronchial Asthma

  • There is reduction in airway diameter.
  • FEV1 is reduced to less than 40% of predicted. .y Peak expiratory flow rate (PEFR) is less than 40% of predicted.
  • There is hypoxia and ventilatory failure.
  • There may be hypocapn~ and respiratory alka­I~.
  •  There may be metabolic acidosis in acute se­vere asthma.
  • There may be cyanosis.

Clinical features Bronchial Asthma

  •  There is a triad of dyspnoea, cough, wheezing.
  • · There is tachypnea, sense of constriction in chest,
  • nonproductive cough, wheezing in inspiration and expiration, prolonged expiration, tachycardia”
  • systolic hypertension. •
  • Anteroposterior diameter of thorax is increased.
  • Wheezing is high-pitched and there is loss of an . sOUnds in severe cases.
  • Accessory muscles become active.
  • There is paradoxical pulse due to large negative intrathoracic pressu re.
  • There may be productive cough with mucus of­ten as casts called Curschmann’s spirals. These are laden with eosinophils and Charcot-Leyden crystals.
  • Respiration may change from tachypnea to gasp­ing.
  • Patient then needs ventilatory support.
Complications Bronchial Asthma
  • Atelectasis
  • Spontaneous pneumothorax
  • Pneumomediastinum.

Diagnosis

  •  In asthma there is reversible airway obstruction.
  • Reversibility is a 15% or more increase of FEV1
  • after 2 puffs of beta adrenergic agonist.
  • The FEV and PEFR are reduced.

Treatment OF Bronchial Asthma

  • Quick relief medications: Beta adrenergic agonists, metQylxanthines, anticholinergics.
  • Beta adrenergic agonists :
  • These are catecholamines, resorcinols and saligenins.
  •  Catecholamines e.g. epinephrine, isoproter­enol.
  • They are short acting and given by inhalation or parenterally.
  •  Resorsinols e.g. Fenoterol.
  • Resorsinols have no cardiac side effects.
  • Saligenins e.g. Albuterol (salbutamol).
  • Long acting beta 2 agonists e.g. Terbutaline, Salmeterol, Formeterol.
  • Methyl xanathines e.g.
  • Theophylline Common side-effects of theophylline are ner­vousness, nausea, vomiting, anorexia, headache and even seizures and cardiac arrhythmias.

 Long term control medications:

  • Glucocorti­coids, long acting beta 2 aganists, mast cell stailizing agents, leukotriene modifiers, methylxanthines.
  • Glucocorticoids – have anti-inflammatory and preventive role. Its effects are not immedi­ate and only seen after 6 hrs of administra­tion.
  • Prednisone is given 60 mg every 6 hours.
  • In acute asthma methyl prednisolone IV 120­180 mg is given 6 hrly.
  • Inhaled glucocorticoids : These are b.eclomethasone, budesonide, fluticasone.
  • Mast cell stabilizing agents: Promolin sodium, Nedocromil sodium. Effective in atopic asthma
  • Leukotrine modifiers: These reduce the syn­thesis of leukotrines. E.g. Zileuton, Zafirlukast, Montelukast.

Miscellaneous agents Bronchial Asthma

  • Expectorants, mucolytic agents, IV fluids, tranquiliz­ers.

Approach to a Case of Bronchial Asthma

  • · Evaluation of symptoms.
  • · Monitoring of respiratory parameters.
  • · Avoidance of allergens.
  • · For acute cases use short-acting drugs – Inhaled Albuterol, IV Aminophylline.
  • Beta 2 agonists every 20 minutes by inhalation for 2 – 3 doses.
  • · Anticholinergics like ipratropium may be added.
  • · Inhalational agents may be given by jet nebu­lizer, metered dose inhaler, or dry powder inhal­ers in acute situations.
  • · For respiratory emergency like paradoxical pulse, use of accessory muscles, FEV1 <20% and dis­turbed arterial blood gases-intensive manage­ment,  glucocorticoids, ventilatory support may be required.
  • ·If PaCO2 is elevated, patients need intensive care. In severe airway obstruction 80% helium and 20% oxygen may be useful.
  •  For chronic asthma – mast cell stabilizing agents, g1Ucocorticoids, methylxnnthines, long-acting !5eta 2 agonists may be used.
  • · Cigarette smoking must be stopped in all asthma patients.
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