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CHILDHOOD ASTHMA. By: M.A. Kibel and E. Weinberg. Question 1. How would you define asthma?. Answer 1. DEFINITION OF ASTHMA A lung disease characterised by: Airway obstruction (or narrowing) usually reversible, either spontaneously or with treatment Airway inflammation
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CHILDHOOD ASTHMA By: M.A. Kibel and E. Weinberg
Question 1 • How would you define asthma?
Answer 1 • DEFINITION OF ASTHMA A lung disease characterised by: • Airway obstruction (or narrowing) • usually reversible, either spontaneously or with treatment • Airway inflammation • Airway hyper responsiveness to a variety of stimuli Contd
1 continued Asthma is a condition characterised by episodes of cough, wheezing and breathing difficulty due to reversible narrowing of the airways, in response to various stimuli. Airway narrowing and obstruction result from a combination of
1 continued * airway smooth muscle spasm * oedema of the mucosa * plugging of smaller airways by mucus * inflammation Contd
1 continued • "Any child, regardless of age, who has had three or more episodes of wheezing and/or dyspnoea,should be considered as having asthma until proved otherwise".
Question 2 • How common is asthma?
Answer 2 • In industrialised countries asthma occurs in 1 to 2 out of every 10 school children. Limited studies in South Africa show a prevalence of between 3.5 and 6%, and it appears to be less prevalent Contd
2 continued • in rural than in urban settings. It is certainly the commonest chronic disorder of childhood, and hospital admissions for asthma show a rising incidence world-wide.
Question 3 • What causes asthma?
Answer 3 • Inflammation is now known to be the key factor in the pathology of asthma. Exposure to allergens and other irritants activate pulmonary mast cells, setting off immediate bronchospasm,
3 continued • followed later by inflammation, in which eosinophil and lymphocytic infiltration, subepithelial collagen deposition and epithelial damage are all involved. • The cascade of effects leading to the asthmatic attack are shown in the following 2 slides:
THE ASTHMATIC INFLAMMATORY CASCADE Inflammatory Stimuli Cell Activation/Mediator Release: Eosinophils Mast Cells Mascrophages Neutrophils T cells Bronchial epithelial cells ASTHMATICINFLAMATION Bronchial Hyperresponsiveness Clinical Asthma
THE ASTHMATIC INFLAMMATORY CASCADE Inflammatory Stimuli Allergens Infections Generic factors Environmental factors Other Cell Activation/Mediator Release
Question 4 • What factors can bring on asthma?
Answer 4 • There are many factors that precipitate attacks. Most important are: • allergen exposure • viral respiratory infections • irritants: tobacco smoke • other forms of smoke • exercise • climatic change • emotional factors
Question 5 • What are the key elements in the history which will lead you to the diagnosis?
Answer 5 • Diagnosing Asthma: the Medical History Review • symptom onset, duration, frequency & pattern • Possible allergic components • Precipitating & aggrevating factors, including lifestyle changes • Management & treatment history • Family history Contd
5 continued • full family history must be taken. There are often other family members with asthma or other allergies. A history of night-time coughing or wheezing, or such symptoms after exercise are strong pointers to a diagnosis of asthma. Details as to seasonality and exposure to possible allergens such as pets or grasses must be elicited.
Question 6 • What are the findings on clinical examination?
Answer 6 • Diagnosing Asthma: The Physical Exam • Examine the character of breath sounds • Check for non-wheezing signs of asthma • Note other allergic diseases • Look for generalised lung hyperinfection • However • Typically, signs and symptoms are episodic • physical exam maybe completely normal • Exclude asthma look - a - likes Contd
6 Continued • While a thorough examination of the respiratory system may elicit abnormalities, these are often lacking at the time of examination. Simple respiratory function tests are an essential part of the clinical examination, and can readily be carried out in children of 5 years and older.
Question 7 • How is respiratory function testing performed?
Answer 7 • A peak flow meter is the simplest and cheapest method to estimate the maximum flow of air during expiration. • Reference must be made to a chart of normal values, based on the child's height. Contd
7 continued • A reduction of 15% after exercise, or an improvement of 15% after inhalation of a beta2 agonist are strong evidence of asthma.
Question 8 • How may these objective measurements of lung function be used?
Answer 8 Objective Measures of Lung Function Enable the Physician to: • Diagnose • airflow obstruction • reversibility • Monitor • changes over time • daily variation • Manage Exacerbations • severity of obstruction • response to therapy Contd
8 Continued • In younger children a therapeutic trial with a bronchodilator can be used to establish the diagnosis. A significant lessening in symptoms strongly favours the diagnosis of asthma. Parents can be given an asthma diary to record the frequency and severity of symptoms.
Question 9 • What are the important conditions which can mimic asthma?
Answer 9 • Ascariasis • Tuberculous mediastinal glands • Cystic Fibrosis Contd
9 Continued • Although the list of conditions which can cause recurrent cough and/or wheezing is a long one, 3 disorders stand out because of their importance and/or frequency; they should always be considered.
Question 10 • What are the important environmental triggers?
Answer 10 Contd
10 Continued • The major allergens in Southern Africa are: House dust mite cat dog grasses
Question 11 • How would you treat an acute attack?
Answer 11 • Managing Acute Exacerbations in the Emergency Department: Initial Treatment • Inhaled short-acting B2 agonist x3 doses over 60 to 90 minutes - or • subcultaneous B2 agonist x3 doses over 60 to 90 minutes Contd
11 continued • Supplemental oxygen for: • hypoxemic patients • all patients if oximeter is unavailable • Consider systemic corticosteroids if: • no response within 1 - 2 hours - or • patient is regularly taking oral steroids. Contd
11 continued • Beta2 agonists in inhaled form are the most useful preparations, and the metered dose inhaler (MDI) is the most convenient and cost- effective method of administration (examples: salbutamol and fenoterol). In young children who cannot inhale the aerosol efficiently, a paper cup can be used as a face mask. A hole is cut in the base of the cup large enough to take the mouth piece of the MDI.
11 continued • Specially designed spacer devices are also available for this purpose. • Nebulisers are convenient for home use. These are simply air compressors which nebulise the solution via a face mask. Infants and young children often respond better to ipratropium bromide solution, which can be added to the beta2 agonist solution. Contd
11 continued • DOSAGES AND METHODS OF ADMINISTRATION OF SALBUTAMOL, FENOTEROL, IPRATROPIUM • Infants and under 5's spacer/cup 3 puffs 2-3 hr nebuliser 0.5 ml in 1ml saline • 5 - 8 years powder inhaler 1 every 3-4 hrs • over 8 years MDI 2 puffs 2- 3 hrs
Question 12 • When should an attack be regarded as severe?
Managing Acute Exacerbations in the Hospital Assess severity Initial treatment Severe episode Reassess Moderate Episode Incomplete Response Poor response Good Response Admit to Hospital Not Improved Admit to ICU Discharge Improved
12 continued • Status asthmaticus should be diagnosed when • There is no response to 2 puffs of beta agonist, 30 minutes apart, or to 2 nebulisations. • the child is anxious, with breathing so laboured that speech is not possible.
12 continued • child uses accessary muscles of respiration, with marked chest hyperinflation. • diminished breath sounds with intense wheezing on auscultation. • pulsus paradoxicus greater than 10 mm during inspiration.
Question 13 • What are the important principles of management?
Answer 13 THE 4 H'S • HOSPITALISE • TREAT HYPOXIA • ADMINISTER HYDROCORTISONE • HYDRATE ADEQUATELY
Question 14 • What are the asthma triggers in the environment that we can most easily modify?
Answer 14 • Tobacco smoke. Smoking parents harm their children: the greater the exposure to passive smoking the worse the symptoms. This is the most important preventable factor. • House dust mite. Use the minimum of curtains and carpeting. Beat mattress and bedding outside regularly, and expose them to sunlight. • Avoid SULPHUR DIOXIDE in cool drinks
Question 15 • What can we do to lessen exposure to house mites?
Answer 15 Measures to Control House Dust Mites • Essential • encase mattress and pillow in an airtight cover • wash bedding weekly in hot water • avoid lying on upholstered furniture • Desirable • reduce indoor humidity to <50% • remove carpets from bedroom and those laid over concrete