（医学课件）支气管哮喘(双语).ppt

1、What Is Asthma?,Asthma is a disease that characterized by: Airway obstruction that is reversible either spontaneously or with treatment chronic airway inflammation Increased airway responsiveness to a variety of stimuli Inflammation causes recurrent episodes of wheezing, breathlessness, chest tightn

2、ess and coughing, particularly at night or early morning,1,Epidemiology,17-20 million Americans (6-10% prevalence) 1% estimated prevalence in mainland of China 10 million medical visits 2 million emergency visits 0.5 million hospitalization 5000 deaths annually Major cause of school and work absence

3、 At least 12 billion per year Increasing burden for years,2,Impact Of Asthma On Patients,Psychosocial: Poor self-esteem Anxiety about asthma Fear of becoming ill at out-door Anxiety about exercise Fear of being different,3,Did You Know.,Asthma kills people equally regardless of severity level 1/3 of

4、 deaths are in those with mild asthma 1/3 of deaths are in those with moderate asthma 1/3 of deaths are in those with severe asthma,4,What Causes Asthma?,Asthma may be caused by genetic, immune and/or environmental factors, and is often associated with eczema and allergies We do not understand all o

5、f the causes of asthma or its increasing prevalence It boils down to “We just dont really know for sure”,5,What Causes Asthma,Of the 17 million asthma sufferers in the US, 10 Million (approx. 60%) have allergic asthma. 3 million of those are children Exposure to certain allergens trigger asthma symp

6、toms to begin Exposure to certain irritants can also set an asthma episode in motion,6,Triggers and Irritants,7,Common Allergens (Triggers),Seasonal Pollens Animal dander saliva/urine Dust Mites Cockroaches/Mice/Rat droppings and urine Mold Some medications Some Foods,8,Common Irritants (Triggers),E

7、xercise Cold Air Chalk Dust Viral/upper respiratory infections Air pollution Tobacco smoke or secondhand smoke,Chemical irritants and strong smells Strong emotional feelings Diesel fumes Cleaning supplies,9,RV-Induced Airway Inflammation,10,Viruses cause asthma exacerbations RVs cause 60% of virus-i

8、nduced exacerbations of asthma RVs directly infect the bronchial airways The response to viral infection is shaped by the hosts antiviral response,RV-Induced Asthma,11,Nakano, Y. et al. Chest 2002;122:271S-a-275S-a,Pathophysiologic schema for the development of asthma,12,The Allergic Reaction,13,The

9、 Asthma Cascade,14,15,Mediator Phases,Early-phase reaction caused by mediator release, usually peaks within an hour after initial exposure to the allergen. Three to four hours after an acute asthma episode, a late-phase reaction may occur and may last up to 24 hours,16,The End Results Of The Cascade

10、,Localized mucosal edema in the walls of the small bronchioles Secretion of thick mucus into the bronchiolar lumens (Clogs and narrows the airways) Spastic contraction of bronchiolar smooth muscle,17,Normal Bronchiole Inflamed Bronchiole with Mucus,18,Airway Obstruction,Copyright 3M Pharmaceuticals

11、2004,19,20,Remodeling Phases,Airway wall thickening. Subepithelial fibrosis Smooth muscle hyperplasia and hypertrophy Myofibroblast hyperplasia Mucus metaplasia,21,Vignola, A. M. et al. Chest 2003;123:417S-a-422S-a,Increased thickness of the basement membrane (arrow), and enhanced and abnormal depos

12、ition of fibronectin, which is identified by immunohistochemistry using a specific monoclonal antibody (dashed arrow), in the bronchial submucosa,22,Increased thickness of the basement membrane , and enhanced and abnormal deposition of collagen in the bronchial submucosa,23,A Lot Going On Beneath Th

13、e Surface,24,Common Symptoms Of Asthma,Frequent cough, especially at night Shortness of breath or rapid breathing Chest tightness Chest pain Wheezing Fatigue,25,Early Signs Of An Asthma “Episode”,Mild cough Drop in Peak Flow reading Itchy, watery or glassy eyes Itchy, scratchy or sore throat Runny n

14、ose,Stomachache Headache Sneezing Congestion Restlessness Dark circles under eyes Irritability,26,Measures Of Assessment And Monitoring,Two Aspects: Initial assessment and diagnosis of asthma Periodic assessment and monitoring,27,Initial Assessment & Diagnosis of Asthma,Determines That: Patient has

15、a history or presence of episodic symptoms of airflow obstruction Airflow obstruction is at least partially reversible Alternative diagnoses are excluded,28,Methods for Establishing Diagnosis,Detailed medical history Physical exam: wheeze and rhonchus (rhonchi) Spirometry to demonstrate reversibilit

16、y,29,Diagnosis of asthma,Objective measurements 20% diurnal variation on 3 days ina week for 2 weeks on PEF diary or FEV1 15% (and 200ml) increase after short acting 2 agonist or steroid tablets or FEV1 15% decrease after 6 minutes of running exercise histamine or methacholine challenge in difficult

17、 cases,Symptoms (episodic/variable) wheeze shortness of breath chest tightness cough,Signs none (common) wheeze diffuse, bilateral, expiratory ( inspiratory) tachypnea,Helpful additional information personal/family history of asthma or atopy history of worsening after aspirin/NSAID, blocker use reco

18、gnised triggers pollens, dust, animals, exercise, viral infections, chemicals, irritants pattern and severity of symptoms and exacerbations,Consider the diagnosis of asthma in patients with some or all of these features,30,Asthma Lung Assessment Spirometry,Spirometry is Gold standard to assist in as

19、thma diagnosis Performed before and after bronchodilator dose to look for airway obstruction reversibility Can also be done with histamine or methylcholine challenge, or an exercise challenge in the case of exercise-induced asthma,31,Is Airflow Obstruction At Least Partially Reversible?,Use spiromet

20、ry to establish airflow obstruction FEV1 15% and at least 200 mL after using a short-acting inhaled beta2-agonist,32,Peak Expiratory Flow Variability,An another way to evaluate airway obstruction There is the difference between the morning and evening PEF readings PEF readings tend to be higher in t

21、he evening than in the morning,33,Peak Flow Meters,34,Differential diagnosis ofasthma,Some of symptoms of asthma are shared with diseases of other systems,Numerous relatively common lung diseases,Need to differentiate from infections and restrictive lungdisorders, and between local and generalised o

22、bstruction,35,Asthma Severity Levels,Mild Intermittent Mild Persistent Moderate Persistent Severe Persistent,36,Asthma Severity Levels By Symptoms,Mild Intermittent - Sx 2x/week but 2 nights / month Moderate Persistent - Sx every day Sx 1 night/week Severe Persistent - Continual daytime Sx Frequent

23、Sx at night,37,Mild Intermittent,Symptoms 2 days/week with nighttime symptoms 2 nights/month Asymptomatic with normal peak flows between exacerbations Exacerbations are brief (hours to a few days) Peak Flows 80% predicted with variability 20%,38,Mild Persistent,Symptoms 2 days /week but 1x/day with

24、nighttime symptoms greater than 2 nights/month Exacerbations may affect activity Peak flow 80% predicted with variability of 20-30%,39,Moderate Persistent,Child is likely to have daily symptoms and use reliever daily Child is waking up at least once a week due to asthma symptoms Peak flows 60-80% of

25、 predicted with variability of 30% Activity is affected and exacerbations may last days,40,Severe Persistent,Continual daytime symptoms with frequent nighttime symptoms Very limited physical activity Frequent exacerbations Peak flows 60% of predicted and variability of more than 30% Treatment involv

26、es a combination of many drug therapies,41,Goals Of Asthma Therapy,Prevent chronic and troublesome symptoms Maintain “normal” pulmonary function Maintain normal activity levels-including exercise and other physical activity Minimize the need for emergency room/urgent care visits or hospitalizations,

27、42,Goals Of Asthma Therapy Continued,Prevent recurrent exacerbations of symptoms Provide optimal pharmacotherapy with minimal or no adverse effects Satisfy the patients and the familys goals for asthma care,43,Stepwise Approach To Asthma Therapy,Outcome: Best Possible Results,44,Bronchodilators Relaxing bronchial smooth muscle to open up the airway. Anti-inflammatory agents Inhibiting the development of airway inflammation and stopping ongoing inflammation. In combination, treat and prevent reversible airway obstruction and airway hyperresponsiveness, relieve the symptom a