Acute Asthma Attack

Triggers for an attack

• Respiratory infection
• Allergens
• Airborne irritants
• Air temperature change (particularly hot to cold)
• Exercise
• Emotional factors (e.g. laughing/stress/hyperventilation)
• GORD
• Drugs (NSAIDs/Beta blockers)
• Foods

Features/Investigations

• Severe breathlessness; tachypnoea; tachycardia
• In severe cases there are other features (see below)
• Patients should have PEFR (or FEV1) measured where appropriate; Pulse oximetry is important in all patients
• Blood gases and CXR may be appropriate in acute severe or life-threatening exacerbations

Assessment

• Moderate
  • Increasing symptoms 
  • PEF >50-75% best or predicted
  • No features of acute severe
• Acute severe
  • Any one of:
    • PEFR 33-50% best or predicted best
    • Respiratory rate >=25bpm and heart rate >= 110bpm
    • Inability to complete sentences in one breath
• Life-threatening
  • Any one of
    • PEFR <33% best/predicted best
    • SpO2 <92%
    • PaO2 <8kPa
    • normal PaCO2 (i.e. 4.6-6kPa)
      • usually low PaCO2 in an exacerbation; if normal this could be a sign of deterioration; if high, this could be near fatal
    • silent chest
    • cyanosis
    • poor respiratory effort
    • arrhythmia
    • exhaustion, altered conscious level
• Criteria for admission
  • Any patient with life-threatening features or those who could require assisted ventilation
  • Any patient with an acute severe attack which persists after initial treatment
  • Any child who does not respond to 10 puffs (2 puffs every 2 minutes) of beta-agonists
• Criteria for discharge
  • If a patient is well and PEFR >75% after one hour of initial treatment (unless other reason for admission)

Management

• ABCDE approach is important.  Where an asthma exacerbation is likely, include the following at the appropriate steps
• Oxygen therapy
• Inhaled high dose Beta-agonists (nebulised with oxygen is recommended but not essential)
  • Add nebulised ipratropium bromide in acute severe/life-threatening asthma or those with a poor response to beta-agonists
  • In children a single dose of IV salbutamol may be considered if there is no response to inhaled agonists
• Consider a single dose of IV magnesium sulphate for patients with acute severe asthma who do not respond or in all cases of life-threatening/near fatal asthma
• Steroids – NB Give in all cases of acute asthma
  • Give early in children (20mg 2-5 years; 30-40mg in >5 years)
    • Consider IV steroids if required in children
  • Continue 40-50mg for 5 days after (or until full recovery)
• If patient continues to decline or makes no improvement with life-threatening asthma, referral to ICU may be required