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 |
| Severe | - PEF ≤50% predicted or personal best |
| Life-Threatening | - PEF <25% predicted or personal best |
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)
- Position: Head up ≥30°
- Put on nasal cannula 6L/min (subsequently dialed up to 15L/min)
- Ketamine IV 1mg/kg over 30 seconds
- 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).