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Asthma

Asthma. Renmin Hospital, Wuhan University Ding Xuhong ( 丁续红 ). DEFINITION A clinical syndrome of unknown etiology characterized by three distinct components (1) Recurrent episodes of airway obstruction that resolve spontaneously or as a result of treatment (clinical manifestation).

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Asthma

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  1. Asthma Renmin Hospital, Wuhan University Ding Xuhong (丁续红)

  2. DEFINITION A clinical syndrome of unknown etiology characterized by three distinct components (1)Recurrent episodes of airway obstruction that resolve spontaneously or as a result of treatment(clinical manifestation)

  3. (2)An exaggerated bronchoconstrictor response to stimuli that have little or no effect in nonasthmatic subjects, a phenomenon known as airway hyperresponsiveness (Pathophysiologically)(3) Inflammation of the airways as defined by a variety of criteria (Pathogenesis)

  4. PATHOLOGY Constriction of airway smooth muscle Airway epithelium thickening Mucus plugging

  5. Lung Hyperinflation in Asthma

  6. Thickbronchi with Mucous plugs

  7. Mucous plug in asthma

  8. Asthma - Microscopically • Patchy necrosis of epithelium • Sub-mucosal glandularhyperplasia • Hypertrophy of bronchial smoothmuscle • Eosinophils,mastcells,lymphocytes (Th2) infiltration

  9. Asthma Microscopic Pathology Obstructed Inflammed Bronchi

  10. PATHOGENESIS OF ASTHMA

  11. Asthma Pathogenetic Types • Extrinsic (Allergic/Immune) • Atopic - IgE • Occupational - IgG • Allergic Bronchopulmonary Aspergillosis - IgE • Intrinsic (Non-immune) • Aspirin induced • Infection induced

  12. Predisposing Factors • Atopy • Causal Factors • Indoor Allergens • Domestic mites • Animal Allergens • Cockroach Allergens • Fungi • Outdoor Allergens • Pollens • Fungi • Occupational Sensitizers • Contributing Factors • Respiratory infections • Small size at birth • Diet • Air pollution • Outdoor pollutants • Indoor pollutants • Smoking • Passive Smoking • Active Smoking Risk Factors that Lead to Asthma Development

  13. Airflow Limitation SYMPTOMS Cough Wheeze Dyspnoea Airway Hyperresponsiveness Genetic InducersAllergens,Chemical sensitisers,Air pollutants, Virus infections INFLAMMATION Triggers Allergens, Exercise, Cold Air, SO2Particulates

  14. DIAGNOSIS OF ASTHMA • History and patterns of symptoms • Physical examination • Measurements of lung function

  15. PATIENT HISTORY • Has the patient had an attack or recurrent episodes of wheezing? • Does the patient have a troublesome cough, worse particularly at night, or on awakening? • Does the patient cough after physical activity (e.g playing)? • Does the patient have breathing problems during a particular season (or change of season)?

  16. Do the patient’s colds ‘go to the chest’ or take more than 10 days to resolve? • Does the patient use any medication (e.g. bronchodilator) when symptoms occur? Is there a response? If the patient answers “YES” to any of the above questions, suspect asthma

  17. Physical Examination • Wheeze -Usually heard without a stethoscope • Dyspnoea • Rhonchi heard with a stethoscope • Use of accessory muscles Remember - Absence of symptoms at the time of examination does not exclude the diagnosis of asthma

  18. Blood Finding • Blood eosinophilia, elevated serum level of sIgE • Arterial blood gases: PaO2 between 55 and 70mmHg PaCO2 between 25 and 35mmHg

  19. Radiographic finding In severe asthma, hyperinflation, pneumomediastinum or pneumothorax may be detected

  20. ECG Sinus tachycardia (usually), right axis deviation, right bundle branch block, “P pulmonale”, ST-T wave abnormalities (severe asthma)

  21. Diagnostic testing Diagnosis of asthma can be confirmed by demonstrating the presence of reversible and variable airway obstruction using Peak Flow Meter

  22. Bronchial challenge test: PC20<8mg/mL • Reversibility test: FEV1 increase more than 12% after inhalation of salbutamol, the absolute value of increase >200ml • Variability of PEF diurnally ≥20%

  23. Differential diagnosis • Chronic bronchitis • Heart failure (“cardiac asthma”) • Hypersensitivity pneumonia • Lung cancer

  24. Goals to Be Achieved in Asthma Control • Achieve and maintain control of symptoms • Prevent asthma episodes or attacks • Minimal use of reliever medication • No emergency visits to doctors or hospitals • Maintain normal activity levels, including exercise • Maintain pulmonary function as close to normal as possible • Minimal (or no) adverse effects from medicine

  25. Tool Kit for Achieving Management Goals • Relievers • Preventers • Peak flow meter • Patient education

  26. What Are Relievers? (also known as rescue medication) • Bronchodilator (beta2 agonist) • Quick relief of symptoms (within 2-3 minutes) • Used during acute attacks • Action lasts 4-6 hrs • Not for regular use

  27. Relievers • Short acting 2 agonists Salbutamol (万托林) • Anti-cholinergics Ipratropium bromide（爱全乐） • Xanthines Theophylline • Adrenaline injections

  28. What are Preventers? • Anti-inflammatory • Takes time to act (1-3 hours) • Long-term effect (12-24 hours) • Only for regular use (whether well or not well)

  29. Prevent future attacks • Long term control of asthma • Prevent airway remodeling

  30. Preventers Corticosteroids Anti-leukotrienes Prednisolone, Betamethasone Montelukast, Zafirlukast Beclomethasone, Budesonide Fluticasone Xanthines Theophylline SR Long acting 2 agonists Mast cell stabilisers Bambuterol, Salmeterol Sodium cromoglycate Formoterol COMBINATIONS Salmeterol/Fluticasone Formoterol/Budesonide

  31. Patient Education in the Clinic • Explain nature of the disease (i.e. inflammation) • Explain action of prescribed drugs • Stress need for regular, long-term therapy • Allay fears and concerns • Peak flow reading • Treatment diary / booklet

  32. Status Asthmatic • FEV1 < 40%pred with treatment, PaCO2 increases, developing major complication such as pneumothorax • Close monitoring • Frequent treatments with inhaled β2-agonists, intravenous aminophylline, high-dose intravenous steroid • Oxygen supplement • Antibiotics – if infection exist • If indicated, intubation of the trachea and mechanical ventilation

  33. The Pregnant Asthmatic • No departure from the ordinary management of asthma • No unnecessary medication should be administered • Systemic steroid should be used sparingly • Tetracycline, atropine, terbutaline(博利康尼?), iodine-containing mucolytics should be avoided

  34. Key Messages • Asthma is a common disorder • It produces recurrent attacks of cough with or without wheeze • Between attacks people with asthma lead normal lives as anyone else • In most cases there is some history of allergy in the family

  35. Asthma can be effectively controlled, although it cannot be cured • Effective asthma management programs include education, objective measures of lung function, environmental control, and pharmacologic therapy • A stepwise approach to pharmacologic therapy is recommended. The aim is to accomplish the goals of therapy with the least possible medication

  36. Thank you!

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