,支气管哮喘 Bronchial Asthma,智汇文库,Outline,Burden of Asthma Definition of Asthma Etiology and Mechanism Diagnosis and Classification Asthma Medications Asthma management and Prevention,Burden of Asthma,Health care expenditures very high Developed economies might expect to spend 1-2 percent of total health care expenditures on asthma. Developing economies likely to face increased demand Poorly controlled asthma is expensive; investment in prevention medication likely to yield cost savings in emergency care,Asthma Prevalence and Mortality,Source: Masoli M et al. Allergy 2004,Epidemiology of Asthma,Definition of Asthma,A chronic inflammatory disorder of the airways Many cells and cellular elements play a role Chronic inflammation is associated with airway hyperresponsiveness that leads to recurrent episodes of wheezing, breathlessness, chest tightness, and coughing Widespread, variable, and often reversible airflow limitation,Source: Peter J. Barnes, MD,Mechanisms,Source: Peter J. Barnes, MD,Asthma Inflammation,Source: Peter J. Barnes, MD,Asthma Inflammation,Risk Factors for Asthma,Host factors: predispose individuals to, or protect them from, developing asthma Environmental factors: influence susceptibility to development of asthma in predisposed individuals, precipitate asthma exacerbations, and/or cause symptoms to persist,Factors that Influence Asthma Development and Expression,Host Factors Genetic - Atopy - Airway hyperresponsiveness Gender Obesity,Environmental Factors Indoor allergens Outdoor allergens Occupational sensitizers Tobacco smoke Air pollution Respiratory Infections Diet,Major Indoor Asthma Triggers,Is it Asthma?,Recurrent episodes of wheezing Troublesome cough at night Cough or wheeze after exercise Cough, wheeze or chest tightness after exposure to airborne allergens or pollutants Colds “go to the chest” or take more than 10 days to clear,Asthma Diagnosis,History and patterns of symptoms - Episodic symptoms after an incidental allergen exposure, seasonal variability of symptoms; - Positive family history of asthma and atopic disease; - Symptoms improved by appropriate asthma treatment; Physical examination - May be normal; - The most usual abnormal physical finding is wheezing on auscultation;,Asthma Diagnosis,Measurements of lung function - Spirometry - Peak expiratory flow Measurement of airway responsiveness Measurements of allergic status to identify risk factors Extra measures may be required to diagnose asthma in children 5 years and younger and the elderly,Typical Spirometric (FEV1) Tracings,1,Time (sec),2,3,4,5,FEV1,Volume,Normal Subject,Asthmatic (After Bronchodilator),Asthmatic (Before Bronchodilator),Note: Each FEV1 curve represents the highest of three repeat measurements,Measuring Variability of Peak Expiratory Flow,Measuring Airway Responsiveness,Etiologic Diagnosis Identify environmental factors,Allergen challenge test Skin prick test Specific IgE,Differential Diagnosis,Other forms of obstructive lung disease, particularly COPD Non-respiratory causes of symptoms (e.g., left ventricular failure) Non-obstructive forms of lung disease (e.g., diffuse parenchymal lung disease) Upper airway obstruction and inhaled foreign bodies,Controller Medications,Inhaled glucocorticosteroids Leukotriene modifiers Long-acting inhaled 2-agonists Systemic glucocorticosteroids Theophylline Cromones Long-acting oral 2-agonists Anti-IgE Systemic glucocorticosteroids,Estimate Comparative Daily Dosages for Inhaled Glucocorticosteroids by Age,Drug Low Daily Dose (g) Medium Daily Dose (g) High Daily Dose (g) 5 y Age 5 y Age 5 y Age 5 y,Reliever Medications,Rapid-acting inhaled 2-agonists Systemic glucocorticosteroids Anticholinergics Theophylline Short-acting oral 2-agonists,智汇文库,Pharmacologic Therapy,Long-term control medications corticosteroids inhaled form systemic steroids used to gain prompt control of disease when initiating inhaled tx Long-acting beta2-agonists used concomitantly with anti-inflammatory meds for long-term symptom control especially nocturnal symptoms prevents exercise-induced bronchospasm,Long-term control medications Leukotriene modifiers zafirlukast - leukotriene receptor antagonist zileuton - 5-lipoxygenase inhibitor is alternative therapy to low doses of inhaled steroids/nedocromil/cromolyn alternative tx to low dose inhaled steroids/cromolyn/nedocromil recommended for 12yrs with mild persistent asthma. Further study needed,Pharmacologic Therapy,Quick relief medications Short acting beta2-agonists - relief of acute symptoms Anticholinergics - may provide additive benefit to beta2 drugs in severe exacerbation. May be alternative to beta2-agonists Systemic steroids - moderate-to-severe persistent asthma in acute exacerbations or to prevent recurrence of exacerbations,Pharmacologic Therapy,Treatment/Long Term Control,Corticosteroids Most potent and effective Reduction in symptoms, improvement in PEF an