A quick refresher on how to treat an asthma emergency.

Clinical features

An asthma attack might present with acute shortness of breath and wheeze, or there may have been a longer history of increasing dyspnoea, cough and fatigue.

Clinical findings can vary with severity, from mild wheeze and dyspnoea to respiratory failure. Wheeze is not a good marker of severity, as life threatening asthma may present with the deadly “silent chest”.

The best markers for severity of an acute episode are appearance, mental state and work of breathing.

Differential diagnosis for acute shortness of breath includes allergy/anaphylaxis, bronchiolitis (children), bronchitis, inhaled foreign body, upper airway obstruction, endobronchial disease (tumour, stenosis) congestive cardiac failure, pulmonary embolism and carcinoid tumours.

Management

First-line treatment for an acute exacerbation of asthma is inhaled short-acting beta agonists such as salbutamol.

Anticholinergic agents such as ipratropium bromide and also oral corticosteroids are useful in moderate to severe asthma attacks.

Corticosteroids have been shown to reduce both hospital admission and relapse rates.

Metered dose inhalers (MDI) should always be administered via a spacer device to optimise drug delivery.

While spacers have been shown to be as effective in delivery bronchodilator drugs, nebulisers can be used if the patient has an oxygen requirement or cannot co-ordinate use of an MDI with a spacer. The nebuliser should be driven by air unless there is an oxygen requirement.

Patients with acute exacerbations need frequent review as asthma can improve and deteriorate quickly.

Mild asthma

• Give one dose of salbutamol and reassess after 20 minutes

Moderate asthma

• Give oxygen if saturation < 90%
• Give one dose of salbutamol every 20 minutes for one hour and reassess further requirement; review 10-20 minutes after third dose to decide on timing for further doses
• Consider using nebulised salbutamol (5mg)
• Give one dose of ipratropium every 20 minutes for one hour only
• Give 2mg/kg dose of oral prednisone if patient not improving after salbutamol burst

Severe asthma

• Call 000
• Give oxygen if saturation < 90%
• Give one dose of salbutamol every 20 minutes for one hour and reassess further requirement
• Review 10-20 minutes after third dose to decide on timing for further doses
• If improving, reduce frequency; if not improving, continue doses every 20 minutes
• Consider using nebulised salbutamol (5mg)
• Give one dose of ipratropium every 20 minutes for one hour only
• Give 2mg/kg oral prednisone up to 60mg

Life threatening asthma

• Call 000
• Give oxygen and nebulised salbutamol continuously
• Given nebulised ipratropium
• Give 2mg/kg oral prednisone if patient able to tolerate

Drug doses

Salbutamol

• Metered Dose Inhaler 100mcg/dose
  • Child < 6 years – 6 puffs
  • Child > 6 years and adults – 12 puffs
• Nebuliser
  • Child < 6 years – 2.5mg nebules
  • Child > 6 years and adults – 5mg nebules

Ipratropium

• Metered Dose Inhaler 21mcg/dose
  • Child < 6 years – 4 puffs
  • Child > 6 and adult – 8 puffs
• Nebuliser
  • Child < 6 – 250mcg nebules
  • Child > 6 and adults – 500mcg nebules

Prednisone

• 2mg/kg up to 60mg

Supportive management

Patients may prefer to sit upright to assist their breathing. Oxygen, when required, should be delivered via a high flow device (non-rebreather, Hudson mask) due to the high respiratory rates experienced by patients during an acute exacerbation.

Aftercare

Patients and their families benefit from asthma education about the signs and symptoms of the disease and medication technique. All asthmatic patients need an action plan with which they can initiate treatment at home and understand when to seek medical review.

Pitfalls

Poor inhaler technique is a common reason for treatment failure in asthma so it is important that patients are provided education regarding administration of inhalers.

Large or frequent doses of salbutamol can lead to toxicity which presents with tachycardia, tachypnoea, tremor and agitation. In this instance, you could reduce or stop the salbutamol and monitor for resolution.

References

Cameron, P., Little, M., Mitra, B., & Deasy, C. (2020). Asthma. In Textbook of adult emergency medicine (pp. 267–271). essay, Elsevier.

The Royal Children’s Hospital Melbourne. The Royal Children’s Hospital Melbourne. Retrieved March 17, 2023, from https://www.rch.org.au/clinicalguide/guideline_index/Asthma_Acute/

Dunn, R., Dilley, S., Brookes, J., Leach, D., Maclean, A., Rogers, I., & Borland, M. (2006). The emergency medicine manual (4th ed., Vol. 2). Venom Publishing.