ASTHMA

1. ASTHMA A. K. Nayyar

2. Definition It is a syndrome characterized by AIRFLOW OBSTRUCTION that varies markedly, both spontaneously and with treatment. Narrowing of the airways is usually reversible, but in some patients with chronic asthma there may be an element of irreversible airflow obstruction

3. Cont. It is characterized pathologically by bronchial inflammation with prominent eosinophil infiltration physiologically by bronchial hype-reactivity, and clinically by variable cough, chest tightness and wheeze

4. Epidemiology It affects approximately 10-15% of children and 5-10% of adults Prevalence is greater in industrialized countries Prevalence is increasing world-wide

5. Pathology of asthma Infiltration with inflammatory cells (esp. eosinophils and T-lymphocytes) Patchy epithelial shedding Airway smooth muscle thickening Subepithelial fibrosis Mucus gland and goblet cell hyperplasia widespread mucus plugging in fatal asthma

6. Mechanisms of asthma Inflammation underlies airway hyperresponsiveness The inflammation is of characteristic pattern and it involves interaction between many inflammatory cells This results in the release of multiple inflammatory mediators Inflammatory mediators result in bronchoconstriction, mucus secrition, exudation of plasma and airway hyperresponsiveness

7. Cont. Neural mechanism may amplify the asthmatic inflammation Structural changes may occur with subepithelial fibrosis, airway smooth muscle hyperplasia and new vessel formation. These changes may underlie irreversible airflow obstruction

8. Types of asthma Allergic (extrinsic) asthma Non-allergic (intrinsic) asthma Occupational asthma Aspirin induced asthma Asthma of infancy(<2 yr of age)

9. Allergic asthma Onset usually in childhood May persist into adulthood Remission in adolescence is common Associated with allergic rhinitis and atopic dermatitis in variable combination

10. Intrinsic asthma Onset in adults No external inciter is recognized Often associated with perennial non-allergic rhinitis Accounts for approx. 10% of adult asthma

11. Occupational asthma Due to exposure to chemical sensitizers at work Unrelated to atopic status Some occur in atopics due to allergen exposure at work

12. Aspirin induced asthma Special type of intrinsic asthma It is a metabolic, pharmacological disorder acute asthma attacks on first and subsequent exposure to aspirin and NSAID

13. Asthma of infancy Recurrent bouts of significant airflow limitation in small airways from viral infections Often remits as child gets older not associated with atopy Sometimes called wheezy bronchitis

14. Clinical features Symptoms Triggers Physical signs

15. Symptoms Wheeze-- intermittent, worse on expiration, chracteristically relieved by an inhaled �2- agonist Cough-- usually unproductive Chest tightness SOB Prodromal symptoms may precede an attack

16. Triggers Allergens (house dust mite, pollen, animal dander, moulds) Irritants (tobacco smoke, air pollutants, strong odours, fumes) Physical factors (exercise, cold air, hyperventillation, laughter, crying) Upper respiratory tract viral infections Emotions Occupational agents (chemical sensitizers, allergens) Drugs (beta blockers,NSAID) Food additives (metabisulphite,tartrazine) Change in weather Endocrine factors (menstrual cycle, pregnancy,thyroid disease)

17. Physical signs Expiratory ronchi- widespread Hyperinflation of chest Use of accessory muscles Associated signs: nasal polyps, flexure eczema

18. Features suggestive of asthma in young children Symptom free intervals Nocturnal cough Coughing after exercise Coughing when laughing or crying Good response to correctly inhled or nebulized bronchodilators Personal or family history of atopic disease Onset unrelated to respiratory syncytial virus infection

19. Features suggestive of alternative diagnosis in young children Failure to thrive(? Cystic fibrosis, immunodeficiency) Absence of symptom free interval Sudden onset of persistent symptoms Persistent URTI/ otitis (? ciliary dyskinesia) Vomiting / recurrent pneumonia(? Acid reflux, aspiration) Premature birth (?bronchopulmonary dysplasia) Onset in RS virus season(?Post RSV broncholitis)

20. DD in adults Mechanical obstruction of airways COPD Heart failure PE Vasculitides Carcinoid syndrome with hepatic secondaries

21. Principles of treatment Educate patients to develop a partnership in asthma management Assess and monitor severity with objective measurement of lung function Avoid or control asthma triggers Establish medication plans for chronic management Establish plans for managing exacerbations Provide regular follow-up care

22. Clinical evaluation of severity Number of daytime attacks lasting more than 24 hrs and needing extra medication The presence of completely symptom-free intervals lasting more than 4 weeks without medication The frequency of waking at night due to asthma symptoms The amount of absence from work or school because of asthma The ability of the patients to keep up with peers in normal physical activity The number and type of medications required on regular basis The frequency of using extra relief medications on an �as needed� basis The frequency of hospital admission The of life-threatening episodes