17th February 2025

Acute asthma

Definitions in acute asthma

NICE guidance advises that acute asthma attacks be graded by severity using criteria such as peak flow, observations such as heart rate and respiratory rate, ABG (arterial blood gas) results and clinical symptoms.

Patients presenting with severe or life-threatening asthma attacks should be started on asthma treatment immediately and should be treated in secondary care facilities. Patients with moderate asthma attacks can be trialled on treatment at home or in primary care, in the first instance.

Table 2 Grading of acute asthma

Investigations in acute asthma

These should include:

• ABG if saturations <92% or with other features of life-threatening asthma
• Chest X-ray if there is any suspicion of consolidation, pneumothorax, any features of life-threatening asthma or if the patient is not responding to initial treatment

Management of acute asthma

General management includes:

• Oxygen to keep saturations 94-98%
• Corticosteroids: prednisolone 40 mg for a minimum of 5 days; ICS should be continued during this time
• Salbutamol (SABA): the nebulised route (2.5-5 mg) is preferred if there are any features of acute severe asthma; IV is reserved for those in whom inhaled routes are unreliable, e.g. with altered consciousness
• Ipratropium bromide (short-acting muscarinic antagonist): nebulised; if no response to above treatments
• IV magnesium sulphate if features of acute severe asthma are present

Intensive care referral should be considered with any of the following:

• Ventilatory support is required
• Acute severe or life-threatening asthma failing to respond to therapy, as evidenced by:
  • Investigations: deteriorating PEF, persistent or worsening hypoxia, hypercapnia, worsening acidosis
  • Clinical features: exhaustion, drowsiness, altered conscious state, respiratory arrest

Criteria for discharge

Prior to discharge, a patient should be stable off nebulisers and oxygen for 12-24 hours, have a peak flow >75% of predicted or best, and have had their inhaler technique checked.