Acute Exacerbation of Bronchial Asthma (AEBA)

1.  Rapid clinical assessment

• ABCD approach
• Assess severity of exacerbation [dyspnea severity, RR, Spo2, pulse rate ± PEF ]
• Consider alternative causes (anaphylaxis etc)
• Provide oxygen supplement to alleviate hypoxia
  • Target Spo2 93-95% (Adult), 94-98% (6-12 years old). 
  • For controlled flow oxygen if requires oxygen supplementation.

 

Category	Criteria
Mild/Moderate	- PEF >50% predicted or personal best - Dyspnea limiting activity - Talks in phrases or sentences - Prefers sitting to lying - Possible accessory muscle use - SpO₂ >90% on room air - Heart rate <120
Severe	- PEF ≤50% predicted or personal best - Dyspnea at rest - Sits hunched forward - Talks in words - Agitated, diaphoretic - Accessory muscle use - SpO₂ may be <90% on room air - Respiratory rate >30 - Heart rate >120
Life-Threatening	- PEF <25% predicted or personal best - Too dyspneic to speak - Depressed mental status - Cyanosis - Inability to maintain respiratory effort - Absent breath sounds - Minimal or no relief from frequent inhaled SABA - Bradycardia or hypotension

 

 

2. Beta-2 agonist (short-acting)

Promotes bronchodilation and vasodilation.

 

MILD: 

• MDI Salbutamol + spacer (4-10puffs every 20 minute for first hour)

 

MODERATE-SEVERE: 

• Neb Salbutamol every 20 minutes for first hour
  • >2 years: 1:3 (5mg)
  • <2 years: 0.5:3.5 (2.5mg)

 

SEVERE-LIFE THREATENING: 

• Continuous Neb Salbutamol (10-15mg/hour)

 

Titrate the frequency to every 1-4 hourly depending on the response.

 

3. Systemic corticosteroid

Restoring  beta-adrenergic responsiveness and reducing inflammation.

 

ADULT: Prednisolone 40-50mg PO (5-7 days)
CHILD: Prednisolone 1mg/kg PO; max 40mg (3-5 days)

 

Use intravenous corticosteroid If unable to tolerate orally:

Hydrocortisone :
ADULT: 200mg  IV STAT, then 100mg 6 hourly.
CHILD: 4mg/kg  IV(max: 100mg)

 

4. Anticholinergic (short-acting)

Additive therapy. Affect large, central airways.

 

ADULT: Neb 2.5mg salbutamol/500mcg ipratropium (combivent) every 20minutes for first hour.

Alternative:

• For >5 years old: 
  • Neb A:V:N (2:1:1) = Ipratropium (Atrovent) 500mcg (2ml) : Salbutamol 5mg (1ml) : normal saline (1ml) every 20minutes for first hour
• For 2-5 years old 
  • Neb A:V:N (1:1:2) = Ipratropium 250mcg (1ml) : Salbutamol 5mg (1ml) : normal saline (1ml) every 20minutes for first hour
• For <2years old, to consult paeditric team.

To titrate frequency 2-6 hourly based on the response.

 

5. For SEVERE or LIFE-THREATENING:

A. MAGNESIUM SULFATE

IMgSo4 2g IV over 20 minutes

Child: 25-50mg/kg, max 2g

 

B. MECHANICAL VENTILATION.

Proceed with endotracheal intubation if:

• Depressed mental status
• Inability to maintain respiratory effort
• Not cooperative with inhaled medication administration
• Worsening hypercapnia with respiratory acidosis
• SpO² <92% despite on face mask

In agitated, non cooperative patient; best to preoxygenate with Delayed Sequence Intubation (DSI) 

1. Position: Head up ≥30°
2. Put on nasal cannula 6L/min (subsequently dialed up to 15L/min)
3. Ketamine IV 1mg/kg over 30 seconds
4. BVM + PEEP valve OR put on NIV-ST for 3minutes

Pre Intubation NIV-ST Settings:

• RR 6-8 breaths/minute
• Pressure support = 10cm H20
• PEEP = 5cm H20
• FiO2 = 1.0 (100%)

 

Post Intubation Ventilator Setting: 

Obstructive Lung Strategy

• Low TV (6-8ml/kg ideal body weight)
• Low PEEP (3-5)
• Prolonged I:E  (1:3 - 1:4)
• Lower inspiratory time 0.8s
• Increase flow rate 80L/min
• Watchout for AutoPEEP

 

C. Parenteral beta-agonist

Generally AVOIDED in exacerbation in adult.

- Inhaled SABA are equal or greater efficacy & lower incidence of adverse effects
- No significant benefit

EXCEPTION only for Severe & Life-threatening exacerbation where inhaled bronchodilator are not effective or not feasible

 

Choice: 

Terbutaline (Brycanyl) 

• SC: 0.25mg - may repeat every 20minutes (total 3 doses)
• Infusion (If SC not sufficient): 2.5-10mcg/min

IV Salbutamol

• Bolus: 250mcg over 10minutes (Child: 15mcg/kg over 10minutes)
• Infusion: 5-20mcg/min
• (Child: 1-5mcg/kg/min)

IM Adrenaline

• 0.3 - 0.5mg IM every 20 minutes for 3 doses.

 

D. IV AMINOPHYLLINE.

Not routinely recommended
✓ Narrow therapeutic index
✓ Risk of severe side effect

May be considered as third-line therapy in severe or life-threatening exacerbation.

• Loading dose: 5mg/kg over 30 minutes 
  • For patients not previously on theophylline
• Maintenance dose: 0.5-0.9mg/kg/hour

Requires close and frequent serum level monitoring (therapeutic range: 10-20mcg/mL).

 

E. KETAMINE

May relieve bronchospasm and help avoid intubation.

• Bolus: 0.15 mg/kg.
• Continuous infusion: 0.25mg/kg/hr.

 

6. Disposition

Discharge Criteria

Resolved symptoms with results in PEFR of >70% predicted.

• Discharge plan:
  • Ensure good inhaler technique
  • Modifiable risk factors for exacerbation (smoking etc.)
  • Written Asthma Action Plan
  • Start or increase ICS or ICS-LABA for maintenance therapy.
  • Early referral to primary healthcare clinic (within 2-7 days).

 

 

References

1. Global Initiative for Asthma (GINA). (2023). Global Strategy for Asthma Management and Prevention. Retrieved from www.ginasthma.org

2. National Asthma Education and Prevention Program (NAEPP). (2020). Expert Panel Report 4: Guidelines for the Diagnosis and Management of Asthma. U.S. Department of Health and Human Services, National Institutes of Health.

3. British Thoracic Society (BTS) & Scottish Intercollegiate Guidelines Network (SIGN). (2019). British guideline on the management of asthma: A national clinical guideline. Retrieved from https://www.brit-thoracic.org.uk

4. Kliegman, R. M., St. Geme, J. W., Blum, N. J., Shah, S. S., Tasker, R. C., & Wilson, K. M. (2020). Nelson Textbook of Pediatrics (21st ed.). Elsevier.

5. Wenzel, S. E. (2022). Asthma: Pathogenesis and Treatment. Journal of Allergy and Clinical Immunology, 149(5), 1349–1362. https://doi.org/10.1016/j.jaci.2022.01.003

6. Turner, S., Thomas, M., von Ziegenweidt, J., Price, D., & Douiri, A. (2016). Prescribing trends in asthma: A longitudinal observational study. Archives of Disease in Childhood, 101(5), 519–523. https://doi.org/10.1136/archdischild-2015-309877

7. Kharitonov, S. A., & Barnes, P. J. (2018). Exhaled biomarkers. Chest, 153(5), 1081–1088. https://doi.org/10.1016/j.chest.2017.12.024

8. Murthy, S., & Guntupalli, K. K. (2015). Critical care of severe asthma. Journal of Intensive Care Medicine, 30(5), 295–307. https://doi.org/10.1177/0885066614534842