Asthma: Causes, Symptoms, and Management

Asthma Asthma 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.

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

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 remain Occupational 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.

Classification Asthma is a complex disorder of the airways , can be classified as: Extrinsic Extrinsic implying a definite external cause Intrinsic Intrinsic no causative agent can be identified

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.

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 -adrenoceptor-blocking agents

Aetiology and pathogenesis The two major factors involved in the development of asthma. Atopyand allergy The term atopy describe asthma & hay-fever, that appeared: to run in families to have characteristic wealingskin reactions to common allergens to have circulating allergen-specific IgE Genetic and environmentalfactors affect serum IgElevels. Genetic : Genes, with environmental factors (key role) . Environmental factors Early childhood exposure to allergens and maternal smoking has a major influence on IgE production.

triggers of asthma Environmental exposure to allergen grass pollen, domestic pets Occupational sensitizers Paint sprayers, Nurses Chemical workers Atmospheric pollution Sulphur dioxide Ozone Particulate matter Drugs (oral and/or topical) NSAIDs, asprin, contraceptive -adrenoceptor blocking agents Environmental exposure to allergen Viral infections Rhinovirus Para influenza virus RSV (respiratory syncytial virus) Cold air Emotion Genetic factors Irritant dusts vapour Perfume Cigarette smoke Viral infections Occupational sensitizers Cold air Emotion Genetic factors Irritant dusts vapour and fumes Atmospheric pollution and fumes Drugs (oral and/or topical)

Clinical features The 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 arefluctuations Clinical features Asthma is a major cause of impaired quality of life, impact on work , physical activities, and emotions

Levels of asthma control* Levels of asthma control* Characteristic Controlled Partly controlled Uncontrolled Daytime symptoms None ( <twice/wk) > twice/wk Limitations of activities None Any 3 features of partly controlled asthma present in any wk Nocturnal symptoms/awakening None Any Need for reliever treatment None ( twice/wk) > twice/wk Lung function (PEF or FEV1) Exacerbation Normal < 80% predicted None 1/yr 1 in any wk

Investigations There is no single satisfactory diagnostic test for all asthmatic patients. Lung function tests Peak expiratory flow rate 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 severe chronic asthma when little reversibility? Lung function tests Peak expiratory flow rate (PEFR) on waking, before bed after a bronchodilator before bed after a bronchodilator, Spirometry: : pitfall: asthma is in remission ?

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)

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

Measurement of airway obstruction More 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 2- adrenoceptor agonists (e.g. salbutamol); a large improvement in FEV1 (over 400 mL) and variability in peak flow over time are features of asthma

How to interpret respiratory function abnormalities How to interpret respiratory function abnormalities Measure Measure Asthma Asthma Chronic Chronic Emphysema Emphysema Pulmonary Pulmonary bronchitis bronchitis fibrosis fibrosis FEV1 FEV1 VC VC FEV1/VC FEV1/VC /

How to make a diagnosis of asthma How to make a diagnosis of asthma Compatible 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