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.

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.