Asthma March 2018 | by EMauthor Generalised narrowing of the airways which varies over short periods of time either spontaneously or as a result of treatment •Moderate Asthma oClinical features: ■No features of acute severe asthma ■Increasing symptoms oMeasurements: ■PEF > 50–75 % of best or predicted •Severe Asthma oClinical features: ■Inability to complete sentences in one breath oMeasurements: ■PEF 33–50 % of best or predicted ■Respiratory Rate ≥ 25 breaths per minute ■Heart Rate ≥ 110 beats per minute •Life-threatening oClinical features: ■Silent chest ■Cyanosis ■Feeble respiratory effort ■Arrhythmia, hypotension ■Exhaustion, altered conscious level oMeasurements: ■PEF <33 % of best or predicted ■SpO 2 <92 % ■PaO2 < 8 kPa ■Normal PaCO2 (4.6–6.0) •Near fatal oRaised PaCO2 and/or requiring positive pressure ventilation with raised inflation pressures Investigations in Asthma •Peak expiratory fl ow rate; should be measured in all acute presentations. It should be expressed as a percentage of the patient’s previous best value or predicted best. •Arterial blood gas; is recommended by BTS if SpO2 <92% or other features of lifethreatening asthma are present. •Chest radiographs are not routinely recommended. They should be performed if a pneumothorax, pneumomediastinum, or consolidation is suspected; in life-threatening asthma; if there is failure to respond to treatment; or if mechanical ventilation is required. Treatment in ED •Oxygen to maintain saturations between 94–98 % •Salbutamol. In moderate and severe asthma via a metered-dose inhaler with a large spacer. In asthma with life-threatening features, the nebulized route (oxygen driven) is recommended (e.g. salbutamol 5 mg). oIn patients with a poor response to initial β2 agonist therapy, it can be nebulized continuously. oIntravenous β 2 agonists should be reserved for those patients in whom inhaled therapy cannot be used reliably. •Nebulized Ipratropium bromide (500 mcg) should be added to β 2 agonist therapy in severe and life threatening asthma or in those with a poor initial response to β 2 agonist. It can be repeated every 4–6 hours. •Prednisolone is 40–50 mg for at least 5 days •The dose of intravenous hydrocortisone is 100 mg •Magnesium sulphate is a bronchodilator. It should be given in life-threatening and near fatal asthma, and in those with severe asthma who have had a poor response to inhaled therapy. oMagnesium can be nebulized or given intravenously. 2 g over 20 minutes. •Consider aminophylline Discharge criteria for acute asthma Patients whose PEF is greater than 75 % best or predicted 1 hour after initial treatment may be discharged from the ED. Patients should be discharged with: •Oral prednisolone 40–50 mg for 5 days and inhaled steroids (e.g. beclomethasone inhaler). •Sufficient and in-date inhaled bronchodilator (e.g. salbutamol). •PEF meter. •Written asthma plan. •GP follow up arranged for within 2 days. |
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