On completion of this chapter you should be able to: discuss the stepwise approach to the pharmacological management of asthma in children

Transcription

1 7 Asthma

2 Asthma is a common disease in children and its incidence has been increasing in recent years. Between 10-15% of children have been diagnosed with asthma. It is therefore a condition that pharmacists can expect to see regularly. Pharmacists are in an ideal position to monitor treatment, counsel parents and children on the correct use of asthma inhaler devices and medication, and assist in the management of a child with asthma including in a prescribing role. Objectives On completion of this chapter you should be able to: list the common symptoms of asthma discuss the stepwise approach to the pharmacological management of asthma in children describe the different devices available to deliver asthma medication.

3 Asthma 1. The disease Asthma is a chronic inflammatory disease of the airways characterised by: reversible airflow obstruction bronchial hyper-responsiveness to a wide variety of stimulants inflammation of the airways. Histamine and other inflammatory mediators such as prostaglandins and leukotrienes are released from mast cells. Inflammatory cells, such as eosinophils, infiltrate the airways releasing inflammatory mediators that damage the bronchial epithelium. Mucosal oedema and increased mucus production also occur. The inflamed airways react to a variety of stimuli such as exercise, cold air and environmental pollutants to produce the familiar symptoms of bronchoconstriction. Most childhood asthma is atopic in nature in that it involves an allergic reaction mediated by the immunoglobulin IgE and mast cell degradation. Children can be allergic to various substances including house dust mites, pets and pollen. A family history of asthma or other atopic conditions such as hay fever is a risk factor for the development of childhood asthma. Risk factors for Asthma Genetic e.g. family history, atopy Environmental e.g. air pollution, allergens, cigarette smoke, viral infection Bronchial inflammation Bronchial hyperresponsiveness Bronchial contraction Asthmatic symptoms e.g. wheeze SOB, chest tightness, cough Risk factors for exacerbation e.g. respiratory tract infections, exercise, cold air, drugs (for example beta-blockers, NSAIDs) Symptoms The main symptoms of asthma include: wheeze shortness of breath cough chest tightness. Symptoms are often worse at night or early in the morning leading to disturbances in sleep. 81

4 Introduction to paediatric pharmaceutical care Diagnosis Diagnosis is based on symptoms, clinical and family history, response to treatment and measurement of lung function. One way to monitor lung function is by measurement of the peak expiratory flow rate (PEFR). This measures airflow in the lungs using a peak flow meter. The meter is a simple device into which the child blows as hard and as fast as they can. A reading is obtained which can be compared to a table of normal values based on height, age and sex. Reduction in peak flow reading indicates a narrowing of the airways. Asthmatic patients show variation in peak flow readings throughout the day (readings are usually lower in the morning) and improvement following bronchodilator therapy, showing reversibility. Spirometry is another test of lung function used in the diagnosis and monitoring of asthma patients. An increase in FEV1(forced expiratory volume in 1 second ) of > 12% following bronchodilator therapy supports the diagnosis of asthma. As young children are unable to use peak flow meters or perform spirometry, diagnosis in this age group can be more difficult and is usually based on clinical signs and symptoms and response to treatment. Management Most children with asthma will be managed in primary care and only those with moderate to severe exacerbations or uncontrolled asthma will require admission to hospital. Many pharmacists are involved in running asthma clinics in GP practices and hospitals offering advice on both aspects of care. The aims of treatment of asthma in children include: control of asthma symptoms prevention of exacerbations minimal use of reliever medication minimal side effects of medication achievement of best possible lung function allowing the child to lead as normal a life as possible. These can be achieved by a combination of non-pharmacological and pharmacological management. 82

5 Asthma 2. Non-pharmacological management Pharmaceutical care of children with asthma includes using non-pharmaceutical approaches. These can be summarised as prevention, monitoring and education. Control of triggers As already explained, asthma symptoms can be triggered by various factors such as reaction to dust mites, pets, exercise, cigarette smoke or infection. These triggers will vary between individuals and parents should try to identify any triggers that cause an increase in their child s asthma. These triggers should then be avoided where possible, although not all allergen avoidance strategies have shown a reduction in asthma symptoms. Preventative measures include: regular washing of bedding at high temperatures and use of mattress covers to reduce house dust mite keeping pets out of child s bedroom no smoking indoors ideally parents should not smoke at all where exercise is a trigger, the child can take a short acting beta2 agonist minutes before exercise. Use of peak flow meter Monitoring of asthma at home by use of a peak flow meter should be encouraged. This involves knowing the child s best PEFR when well and regularly recording peak flow readings on a chart. Reduction in peak flow is an indicator of worsening asthma and an increase in medication may be required to prevent a severe attack. Self management plans Self management plans have proved very helpful for adults and children alike. These detail current treatment and describe the steps to be taken in the event of worsening symptoms or reduced peak flow readings. Education Educating parents and children about the condition will often improve compliance with medication and the management of asthma. Points to cover include: what asthma is and the symptoms the difference between relievers and preventers the importance of using preventer therapy regularly when and how to use each medicine that is prescribed how each medicine works common adverse effects. Providing parents and children with other sources of information (such as organisations like Asthma UK) will prove helpful. See for more information. 83

6 Introduction to paediatric pharmaceutical care Activity 7.1 Choose one inhaler device and demonstrate its use to a colleague or member of staff. Ask for feedback on any aspect of your demonstration or explanation which was unclear. Prescription monitoring Monitoring how often prescriptions are presented can be a useful indicator of compliance with therapy and control of asthma. Excessive prescriptions for beta 2 agonists can indicate poor control of asthma, or incorrect use (take into account multidosing which can use up to 10 puffs per dose-see section 3.2). Likewise, fewer than expected prescriptions for corticosteroid inhalers or other preventer therapies can indicate poor compliance. You should take the opportunity to check how often the patient is taking the prescribed medication, check inhaler technique, counsel on correct use of medication and refer to a doctor, if appropriate. 84

7 Asthma 3. Pharmacological management Treatment of young patients with asthma will vary, depending on whether it is the chronic condition or an acute exacerbation that needs to be managed. 3.1 Chronic asthma Treatment of chronic asthma in children, as in adults, is based on a step-wise approach as recommended in the BTS/SIGN guidelines (British guideline on the management of asthma). Medicines used at each stage will depend on the age of the child. The Commission on Human Medicines (CHM) has published guidance on the use of long-acting beta 2 agonists for the management of chronic asthma. You will find details of the advice in the latest edition of BNF-C (Section ) A summary is shown below: Step Under 5 yrs 5-18 yrs 1 Mild intermittent asthma Inhaled short-acting beta 2 agonist as required. Inhaled short-acting beta 2 agonist as required. 2 Regular preventer therapy Add inhaled steroid (1st choice) microgram/day of beclometasone (or equivalent dose of other steroids).*or leukotriene receptor antagonist Add inhaled steroid (1st choice) microgram/day of beclometasone (or equivalent dose of other steroids)*.or other preventer. 3 Initial Add-on therapy Consider trial of leukotriene receptor antagonist (2-5yrs). If < 2 yrs consider going to step 4. Add inhaled long-acting beta 2 agonist and assess response. Increase steroid dose if necessary to 400microgram/day of beclometasone (or equivalent). If control still poor, try other therapies e.g. leukotriene receptor antagonist, or SR theophylline. 4 Persistent poor control Refer to paediatrician Increase dose of steroid to 800microgram/day beclometasone (or equivalent). 5 Continuous or frequent use of oral steroids N/A Maintain dose of inhaled steroids. Add daily oral steroid. Refer to paediatrician. *Doses of inhaled steroid in the BTS/SIGN guidelines are given as beclometasone. Budesonide doses are the same as beclometasone while the equivalent fluticasone dose is half that of beclometasone. Adjustments may also be needed for CFC free beclometasone inhalers depending on brand(see BNF-C) 85

8 Introduction to paediatric pharmaceutical care Key points include: start treatment at the point most appropriate to the severity of the child s asthma early use of inhaled steroids is indicated if beta2 agonist needed three times a week or more, symptomatic 3 times a week or more, child is waking one night a week or more or (in >5yrs) has experienced an exacerbation requiring oral steroids in the previous two years use lowest effective dose of steroid and try add-on therapy before increasing the steroid dose do not use long-acting beta2 agonist without inhaled corticosteroids check compliance and inhaler technique before starting new therapy review regularly step treatment up or down as necessary. Inhaled beta 2 agonists and corticosteroids are preferred to the oral route due to reduced side effects. Local side effects of inhaled steroid can include hoarseness and oral candidiasis. These can be minimised by use of a spacer device, together with advice to rinse the mouth or brush the child s teeth after the dose. If a mask is used with the spacer, the child s face should also be washed after each dose. Systemic side effects such as growth suppression and adrenal suppression can occur with inhaled steroids, particularly at high doses. It is recommended that doses of inhaled steroids in children should not exceed 800microgram/day of beclometasone and budesonide or 400microgram/day of fluticasone. The treatment should be reviewed regularly and doses reduced slowly if control of asthma allows. Activity 7.2 Mrs A presents a prescription for a salbutamol inhaler for her eight year old son. You notice from the PMR that he received one six weeks ago. On asking Mrs A how often he uses it, she tells you he uses it most mornings on waking and also during sports at school. What would you recommend? workbook page Acute asthma Depending on severity, acute exacerbations may be managed at home or may require admission to A&E or hospital. In an acute exacerbation, inhaled beta 2 agonist should be delivered via a spacer (with mask if appropriate for younger children) or nebulised in cases of severe or life threatening asthma. Multidosing, where up to 10 puffs are inhaled per dose via a spacer, is as effective as nebuliser therapy in mild to moderate attacks. This also has reduced side effects and allows the child to be managed at home. Oral steroids given early in an attack can reduce the need for hospitalisation. 86

9 Asthma Hospital treatment can involve any of the following: nebulised beta2 agonists nebulised ipratropium steroids oral or parenteral aminophylline infusion beta2 agonists by IV route oxygen magnesium sulphate. Severe asthma Severe asthma can be fatal and should be treated promptly. Signs of severe asthma in a child include: respiration tachycardia PEFR < 50% of normal too breathless to talk or feed. It is important to remember that wheeze may be absent in severe asthma. Nebulised ipratropium may be added for children with severe symptoms or who are responding poorly to beta 2 agonists. See MHRA advice on usage. Some hospitals use IV salbutamol (15microgram/kg) or terbutaline (10microgram/kg) in severe exacerbations. Short courses of steroids up to three days are recommended, although some children may require longer treatment. Aminophylline infusion may be needed for severe asthma. A loading dose should be given unless the child is on regular oral theophylline. Nebulised beta 2 agonists can be given until the child has improved enough to change to multidosing with a metered dose inhaler and spacer. Discharge can take place when the child is stable on 3-4 hourly inhaled bronchodilators, with PEFR > 75% of best. Regular therapy should then be reviewed and inhaler technique checked. A written self management plan should be provided to assist parents caring for their asthmatic child. 3.3 Devices There are various devices available to deliver inhaled asthma medication. These include: metered dose inhaler (MDI) dry powder inhaler breath activated inhaler. In children, use of a spacer device with a metered dose inhaler is recommended. This allows more medication to reach the lungs, eliminates the need for co-ordination of inhalation and actuation, and reduces local side effects. Spacer devices with an integral face mask are available for young children and babies which reduces the need to use nebulisers in this age group. 87

10 Introduction to paediatric pharmaceutical care Choice of device will depend on the drug, the age of the child, ability of child to use the device effectively and patient preference. Most children below school age are unlikely to be able to use dry powder inhalers. under 5yrs 5yrs and over beta 2 agonists MDI + spacer MDI + spacer or dry powder inhaler steroids MDI + spacer MDI + spacer Unlike steroid inhalers, beta 2 agonists must be taken to school. However, children may be reluctant to use a spacer at school and a dry powder inhaler may be preferred. Parents and children should be taught how to use the chosen device and should then demonstrate the technique to ensure they have understood and are using it effectively. Pharmacists must be competent in the use of the different devices before demonstrating to patients. Activity 7.3 A four year-old girl was admitted to hospital with a severe asthma attack, her second in eight weeks. She needed nebulised salbutamol, oral prednisolone and intravenous aminophylline. a: What side effect is common to all three drugs and should be monitored for? The child is to be discharged on salbutamol and beclometasone inhalers via a spacer. The beclometasone is an addition to therapy. b: What step of the BTS/SIGN guidelines is she now on? c: List three reasons why a spacer is recommended for use with a steroid MDI. d: What counselling points would you cover prior to discharge? workbook page 15 British Guideline on the Management of Asthma May 2008 BTS/Sign ( BNF for Children July