Asthma
Setting & notes:
- Viral illness most common precipitant
- Allergy, drugs (esp aspirin), stress, exercise or other precipitating illness
- Beware “brittle” asthmatic who may appear “well”. May deteriorate very rapidly
- more rapid the onset the more likely to respond and less likely to admit.
- Risk of death: >3ED visits, >2 admissions, ITU/ ETT in past year, steroid use
Presentation
- breathlessness, cough
- collapse
Clinical features
- wheeze, tachypnoea
- tachycardia, hypertension with paradox
| Severity | Features |
|---|---|
| Moderate | PEF >50% best/predicted • Normal speech. RR<25. HR<110 |
| Acute Severe | PEF: 33-50% • No sentences. RR>25. HR >110. |
| Life Threatening | PEF <33%. SaO2 <92% • silent chest, cyanosis, weak resp. effort • brady or dysrrhythmia, hypotension • exhaustion. altered consciousness |
Management
- Oxygen
- β agonists
- Neb Salbutamol – 5mg, continuously if sick
- Neb Adrenaline – 1mg (esp. useful if rapid onset.)
- IV salbutamol – only if neb's failing
- anti-cholinergic
- Neb atropine – 500mcg. (esp for young and COPD type)
- methylxanthines
- aminophylline – dangerous in acute asthma. Cardiotoxic, neurotoxic and causes vomiting (do not want when potential airway compromise)
- steroid
- give early - IV rather than oral if “sick”
- Hydrocortisone 200mg IV- reduces inflammation, increases response to β agents
- Mg SO4
- 20mmol IV over 20min. Aim is to double serum levels.
- β agonists - β2 - bronchodilator effect
- adrenaline - β but also α effects which are useful for vasocontriction about the bronchioles, creating 'indirect' bronchodilation.