Management of acute asthma in adults in hospital

This content is from the BTS/SIGN British guideline on the management of asthma (SIGN 158), 2019.

Immediate treatment

  • Oxygen to maintain SpO2 94–98%.
  • β2 bronchodilator (salbutamol 5mg) via an oxygen-driven nebuliser.
  • Ipratropium bromide 0.5mg via an oxygen-driven nebuliser.
  • Prednisolone tablets 40–50mg or IV hydrocortisone 100mg.
  • No sedatives of any kind.
  • Chest X-ray if pneumothorax or consolidation are suspected or patient requires mechanical ventilation.

If life-threatening features are present:

  • Discuss with senior clinician and ICU team.
  • Consider IV magnesium sulphate 1.2–2g infusion over 20 minutes (unless already given).
  • Give nebulised β2 bronchodilator more frequently e.g. salbutamol 5mg up to every 15-30 minutes or 10mg per hour via continuous nebulisation (requires special nebuliser.
  • Measure arterial blood gases.

Subsequent management

If patient is improving continue:

  • Oxygen to maintain SpO2 94–98%.
  • Prednisolone 40–50mg daily or IV hydrocortisone 100 mg 6 hourly.
  • Nebulised β2 bronchodilator with ipratropium 4–6 hourly.

If patient not improving after 15-30 minutes:

  • Continue oxygen and steroids.
  • Use continuous nebulisation of salbutamol at 5–10 mg/hour if an appropriate nebuliser is available. Otherwise give nebulised salbutamol 5 mg every 15–30 minutes.
  • Continue ipratropium 0.5 mg 4–6 hourly until patient is improving.

If patient is still not improving:

  • Discuss patient with senior clinician and ICU team.
  • Consider IV magnesium sulphate 1.2–2 g over 20 minutes (unless already given).
  • Senior clinician may consider use of IV β2 bronchodilator or IV aminophylline or progression to mechanical ventilation.

Monitoring

Repeat measurement of PEF 15–30 minutes after starting treatment

  • Oximetry: maintain SpO2 >94–98%.
  • Repeat blood gas measurements within 1 hour of starting treatment if:
    • initial PaO2 <8 kPa (60 mmHg) unless subsequent SpO2 >92% or
    • PaCO2 normal or raised or
    • patient deteriorates.
  • Chart PEF before and after giving β2 bronchodilator and at least 4 times daily throughout hospital stay.

Transfer to ICU accompanied by a doctor prepared to intubate if:

  • Deteriorating PEF, worsening or persisting hypoxia, or hypercapnia
  • Exhaustion, altered consciousness
  • Poor respiratory effort or respiratory arrest.

Discharge

When discharged from hospital, patients should have:

  • Been on discharge medication for 12–24 hours and have had inhaler technique checked and recorded.
  • PEF >75% of best or predicted and PEF diurnal variability <25% unless discharge is agreed with respiratory physician.
  • Treatment with oral steroids (prednisolone 40–50 mg until recovery - minimum 5 days) and inhaled steroids in addition to bronchodilators.
  • Own PEF meter and written asthma action plan.
  • GP follow up arranged within 2 working days.
  • Follow-up appointment in respiratory clinic within 4 weeks.

Patients with severe asthma (indicated by need for admission) and adverse behavioural
or psychosocial features are at risk of further severe or fatal attacks.

  • Determine reason(s) for exacerbation and admission
  • Send details of admission, discharge and potential best PEF to GP.

 

       

Diagnostic criteria

Features of acute severe asthma

  • Peak expiratory flow (PEF) 33–50% of best (use % predicted if recent best unknown)
  • Can’t complete sentences in one breath
  • Respiration ≥25 breaths/min
  • Pulse ≥110 beats/min.

Life-threatening features

  • PEF <33% of best or predicted
  • SpO2 <92%
  • Silent chest, cyanosis, or poor respiratory effort
  • Arrhythmia or hypotension
  • Exhaustion, altered consciousness.

If a patient has any life-threatening feature, measure arterial blood gases. No other investigations are needed for immediate management.

Blood gas markers of a life-threatening attack:

  • ‘Normal’ (4.6–6 kPa, 35–45 mmHg) PaCO2
  • Severe hypoxia: PaO2 <8 kPa (60mmHg) irrespective of treatment with oxygen
  • A low pH (or high H+).

Caution: Patients with severe or life-threatening attacks may not be distressed and may not have all these abnormalities. The presence of any should alert the doctor.

Near-fatal asthma

  • Raised PaCO2
  • Requiring mechanical ventilation with raised inflation pressures.

Peak Expiratory Flow Rate – Normal Values

Graph of normal PEF values by age, height, and sex
Adapted by Clement Clarke for use with EN13826 / EU scale peak flow meters from Nunn AJ Gregg I, Br Med J 1989:298;1068-70