1、支气管哮喘支气管哮喘Bronchial AsthmaOutlinen Burden of Asthma n Definition of Asthman Etiology and Mechanismn Diagnosis and Classificationn Asthma Medicationsn Asthma management and PreventionBurden of AsthmanHealth care expenditures very highnDeveloped economies might expect to spend 1-2 percent of total hea
2、lth care expenditures on asthma.Developing economies likely to face increased demandnPoorly controlled asthma is expensive;investment in prevention medication likely to yield cost savings in emergency careAsthma Prevalence and MortalityEpidemiology of AsthmaProportion of population with asthma(%)Cas
3、e fatality rate per 100,000 asthmaticsDefinition of AsthmanA chronic inflammatory disorder of the airwaysnMany cells and cellular elements play a rolenChronic inflammation is associated with airway hyperresponsiveness that leads to recurrent episodes of wheezing,breathlessness,chest tightness,and co
4、ughingnWidespread,variable,and often reversible airflow limitationMechanismsAsthma InflammationAsthma InflammationRisk Factors for AsthmanHost factors:predispose individuals to,or protect them from,developing asthmanEnvironmental factors:influence susceptibility to development of asthma in predispos
5、ed individuals,precipitate asthma exacerbations,and/or cause symptoms to persistFactors that Influence Asthma Development and ExpressionHost Factors Genetic -Atopy -Airway hyperresponsiveness Gender ObesityEnvironmental Factorsn Indoor allergensn Outdoor allergensn Occupational sensitizersn Tobacco
6、smoken Air pollutionn Respiratory Infectionsn DietMajor Indoor Asthma TriggersIs it Asthma?nRecurrent episodes of wheezingnTroublesome cough at nightnCough or wheeze after exercisenCough,wheeze or chest tightness after exposure to airborne allergens or pollutantsnColds“go to the chest”or take more t
7、han 10 days to clearAsthma Diagnosisn 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;n Physical examination-May be norma
8、l;-The most usual abnormal physical finding is wheezing on auscultation;Asthma DiagnosisnMeasurements of lung function -Spirometry -Peak expiratory flownMeasurement of airway responsiveness nMeasurements of allergic status to identify risk factorsnExtra measures may be required to diagnose asthma in
9、 children 5 years and younger and the elderlyTypical Spirometric(FEVTypical Spirometric(FEV1 1)TracingsTracingsTime(sec)FEV1VolumeNote:Each FEV1 curve represents the highest of three repeat measurementsMeasuring Variability of Peak Expiratory FlowMeasuring Airway ResponsivenessEtiologic Diagnosis Id
10、entify environmental factors nAllergen challenge testnSkin prick testnSpecific IgEDifferential DiagnosisnOther forms of obstructive lung disease,particularly COPD nNon-respiratory causes of symptoms(e.g.,left ventricular failure)nNon-obstructive forms of lung disease(e.g.,diffuse parenchymal lung di
11、sease)nUpper airway obstruction and inhaled foreign bodiesController MedicationsnInhaled glucocorticosteroidsnLeukotriene modifiersnLong-acting inhaled 2-agonistsnSystemic glucocorticosteroids nTheophyllinenCromonesnLong-acting oral 2-agonistsnAnti-IgEnSystemic glucocorticosteroidsEstimate Comparati
12、ve Daily Dosages for Inhaled Glucocorticosteroids by AgeDrug Low Daily Dose(g)Medium Daily Dose(g)High Daily Dose(g)5 y Age 5 y Age 5 y Age 500-1000 200-400 1000 400Budesonide200-600 100-200 600-1000 200-400 1000 400 Budesonide-Neb Inhalation Suspension 250-500 500-1000 1000 Ciclesonide 80 160 80-16
13、0 160-320 160-320 320-1280 320Flunisolide500-1000 500-750 1000-2000 750-1250 2000 1250 Fluticasone100-250 100-200 250-500 200-500 500 500 Mometasone furoate200-400 100-200 400-800 200-400800-1200 400Triamcinolone acetonide400-1000 400-800 1000-2000 800-1200 2000 1200 Reliever Medications Rapid-actin
14、g inhaled 2-agonists Systemic glucocorticosteroids Anticholinergics Theophylline Short-acting oral 2-agonistsPharmacologic TherapynLong-term control medications corticosteroids inhaled form systemic steroids used to gain prompt control of disease when initiating inhaled tx Long-acting beta2-agonists
15、 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
16、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 neededPharmacologic TherapynQuick relief medications Short acting beta2-agonists-relief of acute symptoms Anticholinerg
17、ics-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 exacerbationsPharmacologic TherapyTreatment/Long Term ControlnCorticosteroids Most pot
18、ent and effective Reduction in symptoms,improvement in PEF and spirometry,diminished airway hyperresponsiveness,prevention of exacerbations,possible prevention of airway wall remodeling Suppresses:cytosine production,airway eosinophilic recruitment,chemical mediators nLong-acting beta-2 agonists Rel
19、ax airway smooth muscle Duration of action 12 hrs Not used in acute exacerbations Adjunct to anti-inflammatory tx for long-term symptom control especially nocturnal symptomsTreatment/Long Term ControlnLeukotriene modifiers Leukotrienes are potent biochemical mediators released from mast cells,eosino
20、phils,and basophils that:contract bronchial smooth muscle increase vascular permeability increase mucus secretions attract&activate inflammatory cells in airwaysTreatment/Long Term ControlAsthma Treatment/Quick ReliefnShort-acting beta2 agonists Relax airway smooth muscle and increase in airflow in
21、1 canister/mo indicates inadequate control and indicates need to intensify anti-inflammatory tx Regularly scheduled use NOT recommendednAnticholinergics Cholinergic innervation important in regulation of airway smooth muscle tone Ipratropium bromide(quaternary derivative of atropine without its side
22、 effects)Additive benefit with inhaled beta 2-agonists in severe asthma exacerbations Effectiveness in long-term management not demonstratedAsthma Treatment/Quick ReliefnSystemic steroids speed resolution of airflow obstruction reduce rate of relapsenMedications to reduce oral steroid dependence Tro
23、leandomycin,cyclosporin,gold,methotrexate,IV immunoglobulin,dapsone,hydroxychloroquine Asthma Treatment/Quick ReliefAsthma Medication EquipmentMethods of Delivery nMedications may be given by:-Metered Dose Inhaler(MDI)-Dry Powdered Inhaler(DPI)-Nebulizer-OrallynImportant to review technique for all
24、delivery methodsClinical Control of Asthma No(or minimal)*daytime symptoms No limitations of activity No nocturnal symptoms No(or minimal)need for rescue medication Normal lung function No exacerbations_*Minimal=twice or less per weekLevels of Asthma ControlCharacteristicControlled(All of the follow
25、ing)Partly controlled(Any present in any week)Uncontrolled Daytime symptomsNone(2 or less/week)More than twice/week3 or more features of partly controlled asthma present in any weekLimitations of activitiesNoneAnyNocturnal symptoms/awakeningNoneAnyNeed for rescue/“reliever”treatmentNone(2 or less/we
26、ek)More than twice/weekLung function(PEF or FEV1)Normal 80%predicted or personal best(if known)on any dayExacerbationNone One or more/year 1 in any weekGoals of Long-term ManagementnAchieve and maintain control of symptomsnMaintain normal activity levels,including exercisenMaintain pulmonary functio
27、n as close to normal levels as possiblenPrevent asthma exacerbationsnAvoid adverse effects from asthma medicationsnPrevent asthma mortalitycontrolledpartly controlleduncontrolledexacerbationmaintain and find lowest controlling stepconsider stepping up to gain controlstep up until controlledtreat as
28、exacerbationTREATMENT STEPSREDUCEINCREASESTEP1STEP2STEP3STEP4STEP5REDUCEINCREASE Exacerbations of asthma are episodes of progressive increase in shortness of breath,cough,wheezing,or chest tightness Exacerbations are characterized by decreases in expiratory airflow that can be quantified and monitor
29、ed by measurement of lung function(FEV1 or PEF)Severe exacerbations are potentially life-threatening and treatment requires close supervisionManage Asthma ExacerbationsPrimary therapies for exacerbations:Repetitive administration of rapid-acting inhaled 2-agonist Early introduction of systemic gluco
30、corticosteroids Oxygen supplementationClosely monitor response to treatment with serialmeasures of lung functionManage Asthma ExacerbationsAllergen-specific ImmunotherapynGreatest benefit of specific immunotherapy using allergen extracts has been obtained in the treatment of allergic rhinitisnThe ro
31、le of specific immunotherapy in asthma is limitednSpecific immunotherapy should be considered only after strict environmental avoidance and pharmacologic intervention,including inhaled glucocorticosteroids,have failed to control asthmanPerform only by trained physicianSpecial ConsiderationsSpecial c
32、onsiderations are required tomanage asthma in relation to:Pregnancy Surgery Rhinitis,sinusitis,and nasal polyps Occupational asthma Respiratory infections Gastroesophageal reflux Aspirin-induced asthma Anaphylaxis and Asthma1.Develop Patient/Doctor Partnership2.Identify and Reduce Exposure to Risk F
33、actors3.Assess,Treat and Monitor Asthma4.Manage Asthma Exacerbations5.Special ConsiderationsAsthma Management and PreventionProgram:Five ComponentsRevised 2006nAsthma can be effectively controlled in most patients by intervening to suppress and reverse inflammation as well as treating bronchoconstri
34、ction and related symptomsnAlthough there is no cure for asthma,appropriate management that includes a partnership between the physician and the patient/family most often results in the achievement of controlAsthma Management and Prevention Program:Summary A stepwise approach to pharmacologic therapy is recommended.The aim is to accomplish the goals of therapy with the least possible medication The availability of varying forms of treatment,cultural preferences,and differing health care systems need to be considered Asthma Management and Prevention Program:Summary
