• 8% of Canadians > 18 years have asthma.
• Onset is less common with increasing age.
• Typically presents with dyspnea, cough, wheezing and chest tightness.
• Severe cases can be fatal.

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Standard Treatment

• Oxygen
  • Maintain O2 Saturations >92%.
  • Usually not necessary for mild or moderate exacerbations.

• Short Acting Beta Agonist (SABA)
  • Metered Dose Inhaler (MDI) Salbutamol (100 mcg/puff) with spacer.
    • 4 to 8 puffs q20 minutes x 3 doses, then every 1 to 4 hours prn.
  • Nebulized Salbutamol 5-5mg in 3 mLs saline q20 minutes x 3 doses, then 2.5-10mg every 1 to 4 hours prn.
  • If severe exacerbation – give more frequently or continuous.

• Anticholinergics
  • Use alongside SABA for moderate or severe exacerbations.
  • MDI Ipratropium bromide (20mcg/puff) with spacer.
    • 4 to 8 puffs q 20 minutes x 3 doses, then prn.
  • Nebulized Ipratropium bromide 500mcg (with salbutamol) q20 minutes x 3 doses, then q2-6 prn.
  • If severe exacerbation – give more frequently or continuous.

• Glucocorticoids
  • Oral prednisone 50mg OR equivalent.
  • If oral not possible – IV methylprednisolone 40-125mg.
  • May not be necessary for mild exacerbation (depending on patient’s history).

• Magnesium Sulphate
  • For severe exacerbations not responding to initial therapies.
  • 2g Magnesium Sulphate in 100mL D5W given intravenously over 20mins.

Worsening Severe or Life-threatening Exacerbation

Complete Standard Treatment and consider the following:

1. Specialist consult.
2. Consider alternate diagnosis: anaphylaxis, pneumothorax, airway obstruction.
3. Portable CXR and ABG.
4. Non-Invasive Ventilation or Intubation.
5. Adjunctive treatments.

Consider Non-Invasive Ventilation (NIV) in patients not responding to medical therapy if intubation is not imminently required.

• Indicators:
  • Tachypnea RR >25/min.
  • Tachycardia 110/min.
  • Use of accessory muscles of respiration.
  • Hypoxia with a P_aO₂/ FiO₂ ratio, or P/F ratio <200.
  • Hypercapnia with PaCO2 <60 mmHg.
  • FEV1 <50% predicted.
• Avoid NIV if:
  • Agitation or decreased level of consciousness (LOC).
  • Vomiting or profuse secretions.
  • Significant haemodynamic instability.

Intubation if NIV is unsuitable or ineffective

• Maximize medical treatment prior to intubation if possible.
• Indications:
  • Decreased LOC.
  • Respiratory fatigue/silent chest.
  • Inability to maintain oxygenation with non-invasive methods.
  • Worsening hypercapnia or severe acidemia (pH < 7.10).
  • Hemodynamic instability.

Consider Adjunctive Treatments

• Ketamine:
  • May relieve bronchospasm and help avoid intubation.
  • Limited experience, ideal dosing not determined.
  • Bolus 0.1 mg/kg to 2 mg/kg. (Note: 1-2 mg/kg = dose for intubation)
  • Continuous infusion 0.15 – 2.5 mg/kg/hr, if good response to bolus.
• Salbutamol by IV infusion:
  • IV bolus 4mcg/kg then continuous infusion 0.1-0.2 mcg/kg/min.
• Epinephrine:
  • IM 0.3-0.5mg q20mins prn.
  • IV 0.1mg over 5-10mins and q5-15mins prn, OR IV Infusion 1-4mcg/min.
• Heliox:
  • 70:30 (He:O₂) – Reduces turbulent air flow to improve ventilation.
• General Inhalational Anesthesia:
  • Potent bronchodilators, but evidence is limited – consult anesthesia.
  • Halothane, isoflurane, sevoflurane, desflurane.

• Patients with non-life-threatening exacerbations who improve, but do not meet discharge criteria, can undergo a trial of observation before admission.

• Transfer to an acute care center for mild or moderate exacerbations worsening despite treatment, or for any severe or life-threatening exacerbation.

• Consider ICU consult for life-threatening exacerbations or severe exacerbations which do not improve.

Criteria for discharge must be individualized but in general include:

• Asymptomatic or substantially improved symptoms.
• Peak Expiratory Flow (PEF) >80% or PEF 60-80% and improving.
• Normal oxygen saturation.
• No history of near-death exacerbations.
• Understanding of asthma management, and ability to return if worsening.

Arrange at discharge:

• Reliever and Controller Medications.
• Inhaler technique, importance of adherence and action plan.
• 50mg Prednisone PO (OR equivalent) daily for at least 5 days.
• Instructions for follow up with primary care at end of 5 days (based on steroid duration).
• Instructions on returning if worsening dyspnea (PEF < 200 L/min or use of inhaler <2h interval), chest pain, confusion or weakness.

1. Global Initiative for Asthma. Global Strategy for Asthma Management and Prevention, 2019.

   
   

2. Lung Health Foundation: Adult Emergency Department Asthma Care Pathway (EDACP), June 2018.

   
   

3. Sourav Majumdar. Acute asthma exacerbation in adults. BMJ Best Practice. June 2018

   
   

4. Fanta CH. Acute exacerbations of asthma in adults: Emergency department and inpatient management. In UpToDate, Post TW (Ed), UpToDate, Waltham, MA. (Accessed on May 05, 2020)

   
   

5. Alberta Health Services: Provincial Clinical Knowledge Topic – Asthma, Adult – Emergency, October 2017

   
   

6. Cameron, P., Little, M., Mitra, B., & Deasy, C. (2020). Textbook of Adult Emergency Medicine, Chapter 6.2 Pg.267-271

   
   

7. Asthma, by age group. Statistics Canada. Table  13-10-0096-08. 

   
   

8. Goyal, S., & Agrawal, A. (2013). Ketamine in status asthmaticus: a review. Indian journal of critical care medicine: peer-reviewed, official publication of Indian Society of Critical Care Medicine, 17(3), 154.