1 به نام خدا

2 دکترمحمدامامی فوق تخصص ریه عضوهیات علمی دانشگاه

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4 Asthma

5 DEFINITION Asthma is a syndrome characterized by airflow obstruction that varies markedly, both spontaneously and with treatment

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7 PREVALENCE Asthma is one of the most common chronic diseases globally and currently affects approximately 300 million people worldwide

8 World map of prevalence of asthmaLack of a universally accepted definition of asthma makes reliable comparison of reported prevalence from around the world problematic As you can see the countries with the highest prevalence are north america/canada, UK and ireland, Brazil and Peru in South America, and Australia/NZ Scotland, England , wales and Ireland are in the top 10 Those with the lowest are Russia, China, Indonesia/Borneo/papua new guinea, and Greece/poland/bulgaria etc

9 The prevalence of asthma has risen in affluent countries over the last 30 years but now appears to have stabilized approximately 10–12% of adults and 15% of children affected by the disease

10 Asthma can present at any age, with a peak age of 3 yearsIn childhood, twice as many males as females are asthmatic, but by adulthood the sex ratio has equalized

11 The severity of asthma does not vary significantly within a given patientthose with mild asthma rarely progress to more severe disease those with severe asthma usually have severe disease at the onset

12 RISK FACTORS Asthma is a heterogeneous disease with interplay between genetic and environmental factors

13 Endogenous Factors Genetic predisposition AtopyAirway hyperresponsiveness Gender Ethnicity Obesity Early viral infections

14 Environmental FactorsIndoor allergens Outdoor allergens Occupational sensitizers Passive smoking Respiratory infections Diet Acetaminophen (paracetamol)

15 Atopy The strongest risk factor for asthma is a family history of atopy Patients with asthma commonly suffer from other atopic diseases, particularly allergic rhinitis, which may be found in over 80% of asthmatic patients,and atopic dermatitis (eczema) Atopy may be found in 40–50% of the population in affluent countries

16 Genetic PredispositionIt now seems likely that different genes may also contribute to asthma specifically, and there is increasing evidence that the severity of asthma is also genetically determined asthma is polygenic Genetic polymorphisms may also be important in determining the response to asthma therapy

17 Infections Although viral infections (especially rhinovirus) are common triggers of asthma exacerbations, it is uncertain whether they play a role in etiology There is some association between respiratory syncytial virus infection in infancy and the development of asthma

18 Diet The role of dietary factors is controversialdiets low in antioxidants such as vitamin C and vitamin A, magnesium, selenium, and omega-3 polyunsaturated fats (fish oil) or high in sodium and omega-6 polyunsaturated fats are associated with an increased risk of asthma Vitamin D deficiency may also predispose to the development of asthma

19 Obesity an independent risk factor for asthma, particularly in womenthe mechanisms are thus far unknown Asthma occurs more frequently in obese people (body mass index >30 kg/m2) and is often more difficult to control

20 Air Pollution Air pollutants, such as sulfur dioxide, ozone, and diesel particulates, may trigger asthma symptoms, but the role of different air pollutants in the etiology of the disease is much less certain Indoor air pollution may be more important with exposure to nitrogen oxides from cooking stoves and exposure to passive cigarette smoke

21 Allergens Inhaled allergens are common triggers of asthma symptoms

22 Occupational ExposureOccupational asthma is relatively common and may affect up to 10% of young adults Over 300 sensitizing agents have been identified

23 Triggers Allergens Upper respiratory tract viral infectionsExercise and hyperventilation Cold air Sulfur dioxide and irritant gases Drugs (β blockers, aspirin) Stress Irritants (household sprays, paint fumes)

24 Pharmacologic agents All β blockers need to be avoided, and even selective β2 blockers or topical application (e.g., timolol eye drops) may be dangerous Angiotensin-converting enzyme inhibitors are theoretically detrimental as they inhibit breakdown of kinins, which are bronchoconstrictors; however, they rarely worsen asthma characteristic cough is no more frequent in asthmatics than in nonasthmatics

25 Exercise Exercise is a common trigger of asthma, particularly in children EIA is worse in cold, dry climates than in hot, humid conditions

26 Physical factors Cold air Hyperventilation Laughterstrong smells or perfumes

27 Food and diet There is little evidence that allergic reactions to food lead to increased asthma symptoms, despite the belief of many patients Certain food additives may trigger asthma Metabisulfite Tartrazine

28 Air pollution sulfur dioxide, ozone, and nitrogen oxides are associated with increased asthma symptoms

29 Hormones Some women show premenstrual worsening of asthma, which can occasionally be very severe Thyrotoxicosis and hypothyroidism can both worsen asthma

30 Gastroesophageal refluxGastroesophageal reflux is common acid reflux might trigger reflex bronchoconstriction it rarely cause asthma symptoms antireflux therapy usually fails to reduce asthma symptoms in most patients

31 Stress Psychological factors can induce bronchoconstriction through cholinergic reflex pathways

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