Bronchial Asthma PDF

Bronchial Asthma by Osama El-Mishawy,MD Prof. of Medicine  Definition It is a chronic inflammatory disease of the airway that causes periodic "attacks" of coughing, wheezing & shortness of breath. Asthma has 3 character: 1- Airway obstruction which is...

Bronchial Asthma by Osama El-Mishawy,MD Prof. of Medicine  Definition It is a chronic inflammatory disease of the airway that causes periodic "attacks" of coughing, wheezing & shortness of breath. Asthma has 3 character: 1- Airway obstruction which is reversible either spontaneously or with treatment 2-Airway hyperresponsiveness to a wide range of stimuli. 3-Inflammation of the bronchi with epithelial damage, oedema & mucus plugging  Prevalence The prevalence has increased over the last 30 years. This increase is marked in children & young adults, with up to 15% of the population affected. Asthma is more common in developed countries, & much lower in Far Eastern countries.  Classification: Extrinsic – due to external cause. It occurs in atopic individuals at any age but more in children & young adults. Intrinsic or cryptogenic - when no cause can be identified. However this difference is of limited clinical value and extrinsic causes must be considered in all cases of asthma and must be avoided.  Etiology: There are two major factors involved in the development of asthma and many other stimuli that can precipitate attacks Atopy and allergy: The term 'atopy’ Is the genetic tendency to develop allergic diseases as allergic rhinitis, asthma, atopic dermatitis It runs in families It has skin reactions to common allergens in the environment. Allergy any exaggerated immune response to a foreign antigen regardless of mechanism  Pathogenesis: It involves mediators & vascular leakage that can be activated by: different mechanisms, of which exposure to allergens is among the most significant. The severity of asthma is dependent on airway inflammation 1- Mast cells: Are increased in the epithelium of asthmatics and can release powerful mediators acting on smooth muscle & small blood vessels, as histamine, prostaglandin D2 and leukotriene which cause the asthmatic reaction. 2- Eosinophils: These cells are found in large numbers in the bronchial wall and secretions of asthmatics. Both the number and activation of eosinophils is rapidly decreased by corticosteroids.  3- Macrophages & lymphocytes: These cells are increased in mucous membranes of the airways & alveoli. Macrophgages have a role in uptake and presentation of allergens to lymphocytes. They can release prostaglandins, thromboxane, leukotriene and platelet- activating factor (PAF). 4- The epithelium: is damaged in asthma so, it is more subjected to infection by common respiratory viruses, e.g. rhinovirus  Clinical features: The principal symptoms of asthma are wheezing attacks and episodic shortness of breath (dyspnoea). Symptoms are usually worst during the night. Cough is a frequent symptom that sometimes predominates. Nocturnal cough can be a presenting feature.  Investigations: There is no single satisfactory diagnostic test for all patients with asthma. -Lung function tests -Blood and sputum tests: showed increase in the number of eosinophils in peripheral blood and in the sputum. - Allergy Tests for Asthma: Skin-prick tests should be performed in all cases of asthma to help identify allergic causes.  Treatment Control of extrinsic factors such as: - Measures must be taken to avoid causative allergens house-dust mite, pets, & some foodstuffs. - Avoid smoking, salicylates, NSAIDs & B- blockers. - Medications used to treat asthma are divided into two general classes: 1- quick-relief medications used to treat acute symptoms. 2-long-term control medications used to prevent further exacerbation. Metered dose inhalers are the corner-stone in treatment of asthma. a) Long-acting β2 agonists: b) Sodium cromoglicate c) Leukotriene modifiers: e.g. montelukast b) Drugs: Inhaled steroids: e.g. Beclometasone is the most widely used inhaled steroid. Other inhaled steroids e.g. budesonide. Short-acting relievers (β2 agonists) e.g. salbutamol, terbutaline. Long-acting relief/disease controllers Other agents with bronchodilator activity : Antimuscarinic agents (ipratropium, oxitropium) Theophylline-preparations. Thank you