Asthma Asthma is a common chronic inflammatory condition of - PowerPoint Presentation

1. AsthmaAsthma is a common chronic inflammatory condition of the lung airways. Symptoms are: cough, wheeze, chest tightness and shortness of breath, often worse at night. The most frequent form has its onset in childhood 3 - 5 years : either worsen or improve during adolescence.

2. Classically asthma has three characteristics:Reversible airflow limitation Airway hyper-responsiveness Inflammation of the bronchi In chronic asthma, inflammation may be accompanied by irreversible airflow limitation as a result of airway wall remodeling, leading to: fibrosis of the airway wall fixed narrowing of the airway & reduced response to bronchodilator

3. Prevalence of asthma Prevalence is increasing With increase allergy, in children & young adults ,disease may affect up to 15% .Asthma being commoner in more developed countries,‘westernized’ lifestyle, Environmental factors accounting for this remainOccupational asthma, 15–20%, may become asthmatic if exposed to potent sensitizers. Around 300 million people have asthma and this is expected to rise to 400 million by 2025.

4. ClassificationAsthma is a complex disorder of the airways , can be classified as:Extrinsic – implying a definite external causeIntrinsic – no causative agent can be identified

5. Extrinsic asthma Early onset:occurs in: atopic individuals show positive skin-prick reactions to common allergens (dust mite, animal danders, pollens and fungi). Positive SPT in 90% of children and 70% of adults with persistent asthma.Childhood asthma is often ass. With eczema (atopic dermatitis) A frequently overlooked cause of late-onset asthma in adults is sensitization to chemicals or biological products in the workplace.

6. Intrinsic asthma Often starts in middle age (‘late onset’) Adult-onset asthma show positive allergen skin tests history of respiratory symptoms (childhood asthma).Non-atopic individuals may develop asthma in middle age from extrinsic causes (occupational agents) toluene diisocyanate intolerance to NSAID aspirin β-adrenoceptor-blocking agents

7. Aetiology and pathogenesisThe two major factors involved in the development of asthma.Atopy and allergyThe term ‘atopy’ describe asthma & hay-fever, that appeared: to run in families to have characteristic wealing skin reactions to common allergens to have circulating allergen-specific IgEGenetic and environmental factors affect serum IgE levels.Genetic : Genes, with environmental factors (key role) .Environmental factorsEarly childhood exposure to allergens and maternal smoking has a major influence on IgE production.

8. triggers of asthma Environmental exposure to allergen grass pollen, domestic petsOccupational sensitizers Paint sprayers, Nurses Chemical workers Atmospheric pollutionSulphur dioxideOzoneParticulate matterDrugs (oral and/or topical)NSAIDs, asprin, contraceptive β-adrenoceptor blocking agentsViral infectionsRhinovirusPara influenza virusRSV (respiratory syncytial virus)Cold airEmotionGenetic factorsIrritant dusts vapour and fumesPerfumeCigarette smoke

9. Clinical featuresThe principal symptoms are: wheezing attacks episodic shortness of breath usually worst during the night, marker of uncontrolled disease? Cough nocturnal cough the frequency and duration of the attacks Some patients have only one or two attacks / year others have attacks lasting for weeks symptoms that persist, on top of which there are fluctuations Asthma is a major cause of impaired quality of life, impact on work , physical activities, and emotions

10. Levels of asthma control*CharacteristicControlledPartly controlledUncontrolled Daytime symptoms None ( <twice/wk) > twice/wk 3 features of partly controlledasthma present in any wkLimitations of activitiesNoneAnyNocturnal symptoms/awakeningNoneAnyNeed for ‘reliever’ treatmentNone ( twice/wk)> twice/wkLung function (PEF or FEV1)Normal< 80% predicted ExacerbationNone1/yr1 in any wk

11. InvestigationsThere is no single satisfactory diagnostic test for all asthmatic patients.Lung function testsPeak expiratory flow rate (PEFR) on waking, before bed after a bronchodilator, useful in demonstrating the variable airflow limitation that characterizes the disease. Diurnal variation in PEFR is a good measure of: Asthma activity Longer-term assessment Response to treatment Assess possible occupational asthma ( at work and off work) Spirometry: Assessing reversibility. Diagnosed by demonstrating a >15% improvement in FEV1 or PEFR following the inhalation of a bronchodilator pitfall: asthma is in remission ? severe chronic asthma when little reversibility?

12. Other Blood and sputum tests Increase in the number of eosinophils in peripheral blood (> 0.4 × 109/L). Eosinophils in the sputum is a more useful diagnostic tool Chest X-ray No diagnostic features by CX Ray.But over-inflation, during an acute episode or in chronic severe disease May be helpful in:excluding a pneumothorax, (a complication) or detecting the pulmonary shadows (Allergic broncho-pulmonaryaspergillosis)

13. Allergen testsSkin-prick tests (SPT) to identify allergic causes, demonstrate wheal in skin, after contact Measurement of allergen-specific IgE Allergen provocation tests in cases of suspected occupational asthma food allergy causing asthma

14. Measurement of airway obstructionMore accurate BY: inhaling fully, then exhaling at maximum effort into a spirometer. The forced expired volume in 1 second (FEV1) is the volume exhaled in the first second, the forced vital capacity (FVC) is the total volume exhaled. FEV1 is reduced in airflow obstruction, resulting in FEV1/FVC ratios of less than 70%. In this situation, spirometry should be repeated following inhaled short-acting β2- adrenoceptor agonists (e.g. salbutamol); a large improvement in FEV1 (over 400 mL) and variability in peak flow over time are features of asthma

15. How to interpret respiratoryfunction abnormalitiesMeasure AsthmaChronicbronchitis EmphysemaPulmonaryfibrosisFEV1 ↓↓↓ ↓↓↓↓VC↓↓↓↓↓FEV1/VC↓↓↓→/↑

16. How to make a diagnosis of asthmaCompatible clinical history plus either/or :FEV1 ≥ 15%* (and 200 mL) increase following administration of a bronchodilator /trial of corticosteroids> 20% diurnal variation on ≥ 3 days in a week for 2 weeks on PEF record FEV1 ≥ 15% decrease after 6 mins of exercise