When inserting an IV cannula take a blood sample to measure serum electrolytes. Serum potassium levels are often low after multiple doses of β₂ agonists and should be replaced.

If intravenous β₂ agonist infusions are used, consider monitoring serum lactate to monitor for toxicity.

The role of intravenous β₂ agonists in addition to nebulised treatment remains unclear.⁵⁹⁰

A continuous intravenous infusion of salbutamol should be considered when there is uncertainty about reliable inhalation or for severe refractory asthma. This should be given in a high dependency unit with continuous electrocardiogram (ECG) monitoring and twice daily electrolyte monitoring. Doses above 1–2 micrograms/kg/min (200 micrograms/ml solution) should be given in a paediatric intensive care unit setting (up to 5 micrograms/kg/min). Nebulised bronchodilators should be continued while the patient is receiving intravenous bronchodilators. Once the patient is improving the intravenous infusion should be reduced before reducing the frequency of nebulised bronchodilators.

There is no evidence that aminophylline is of benefit for mild to moderate asthma and side effects are common and troublesome.⁶¹², ⁶¹⁴, ⁶⁷³, ⁶⁷⁴

A 5 mg/kg loading dose should be given over 20 minutes (omit in those receiving maintenance oral theophyllines) with ECG monitoring followed by a continuous infusion at 1 mg/kg/hour. Measure serum theophylline levels in patients already receiving oral treatment and in those receiving prolonged treatment.

Intravenous magnesium sulphate is a safe treatment for acute asthma in children not responding to first-line treatment.⁶⁷⁶

There is little high-quality evidence to guide treatment at this stage of an acute asthma attack and it is important to involve a clinician with the appropriate skills in airway management and critical care support as early as possible.

Other therapies

Heliox

There is no evidence to support the use of heliox for the treatment of acute asthma in childhood.

Critical care settings

In children with acute asthma and a poor response to standard therapy (inhaled bronchodilators, steroids, oxygen and intravenous bronchodilators) other therapies may be considered in the appropriate critical care setting with the appropriate available expertise. There is little high-quality evidence to guide treatment at this stage of an acute asthma attack and it is important to involve a clinician with the appropriate skills in airway management and critical care support as early as possible.

Extracorporeal membrane oxygenation

There is no good quality evidence on the use of ECMO in children, probably reflecting, in part, the low number of children who would be suitable for this approach. Extracorporeal membrane oxygenation has, however, been used successfully in other forms of critical respiratory failure in children for a number of years and there are four paediatric ECMO centres in the UK that would consider treating children with near-fatal asthma who are not responding to conventional treatment (Glenfield Hospital, Leicester; The Freeman Hospital, Newcastle; The Royal Hospital for Children, Glasgow; and Great Ormond Street Hospital, London).

Recombinant human deoxyribonuclease

There is no evidence to support the use of recombinant human deoxyribonuclease in acute asthma in children.

Children with asthma not responding to standard treatment should be evaluated by a specialist with the appropriate experience and skills to use and assess medication familiar to those in critical care settings.

Although there is some evidence that NIV is safe and feasible for use in this population, there is little evidence of its effectiveness and insufficient evidence on which to base a recommendation.

Children can be discharged when stable on 3–4 hourly inhaled bronchodilators that can be continued at home.⁶⁸¹ Peak expiratory flow and/or FEV1 should be >75% of best or predicted and SpO2 >94%.

Discharge plans should address the following:

• the diagnosis – clearly document the criteria used to diagnose asthma
• check inhaler technique
• consider the need for preventer treatment or optimising/adjusting previously prescribed preventer treatments
• provide a written PAAP for subsequent asthma attacks with clear instructions about the use of bronchodilators and the need to seek urgent medical attention in the event of worsening symptoms not controlled by up to 10 puffs of salbutamol 4 hourly
• assess exposure to environmental tobacco smoke or actual smoking in older children and refer to suitable agencies where appropriate
• identify the trigger of the acute attack and discuss future management plans for exposure
• arrange follow up by primary care services within two working days
• arrange follow up in a paediatric asthma clinic at about one month after admission
• arrange referral to a paediatric respiratory specialist if there have been life-threatening features.

Many children with recurrent episodes of wheeze triggered by viruses do not go on to develop atopic asthma. The need for regular preventer treatment may depend on the severity and frequency of episodes. Many may not require inhaled corticosteroids.

It is essential that the patient’s primary care practice is informed within 24 hours of discharge from the emergency department or hospital following an asthma attack. Ideally this communication should be directly with a named individual responsible for asthma care within the practice.

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2. 612. Rowe BH, Bretzlaff JA, Bourdon C, Bota GW, Camargo CA, Jr. Magnesium sulfate for treating exacerbations of acute asthma in the emergency department. Cochrane Database Syst Rev 2000(2):CD001490.
3. 614. Parameswaran K, Belda J, Rowe BH. Addition of intravenous aminophylline to beta2-agonists in adults with acute asthma (Cochrane Review). In: The Cochrane Library, 2000.
4. 673. Ciarallo L, Brousseau D, Reinert S. Higher-dose intravenous magnesium therapy for children with moderate to severe acute asthma. Arch Pediatr Adolesc Med 2000;154(10):979-83.
5. 674. Goodman DC, Littenberg B, O'Connor GT, Brooks JG. Theophylline in acute childhood asthma: a meta-analysis of its efficacy. Pediatr Pulmonol 1996;21(4):211-8.
6. 676. Griffiths B, Kew Kayleigh M. Intravenous magnesium sulfate for treating children with acute asthma in the emergency department. Cochrane Database of Systematic Reviews 2016: Issue 4.
7. 681. Stormon MO, Mellis CM, Van Asperen PP, Kilham HA. Outcome evaluation of early discharge of asthmatic children from hospital: a randomized control trial. J Qual Clin Pract 1999;19(3):149-54.