Asthma Flashcards
Define Asthma
Chronic inflammatory airway disease characterised by variable reversible airway obstruction, airway hypersensitivity and bronchial inflammation
What are the Risk factors for Asthma?
Genetic:
- Family History
- Atopy (tendency for T-lymphocytes to drive production of IgE on exposure to allergens)
Common Allergens: House dust mites, pollen, pets, cigarette smoke, viral respiratory tract infection Aspergillus fumigatus spores, occupational allergens
What is the epidemiology of Asthma?
- Affects 10% of children, 5% of adults
- Prevalence appears to be increasing
What are the presenting symptoms?
- Episodic history
- Wheeze
- Breathlessness
- Cough (worse in morning and night)
- Ask about in other atopic disease
Important: ask about previous hospitalised due to acute attacks - gives an indication on severity
What are the precipitating factors of Asthma?
- Cold
- Viral Infection
- Drugs (e.g. beta-blockers, NSAIDs)
- Exercise
- Emotions
What are the signs of Asthma?
- Tachnpnoea
- Use of accessory muscles
- Prolonged expiratory phase
- Polyphonic wheeze
- Hyperinflated chest
Severe attack:
- PEFR <50% predicted
- Pulse >110bpm
- RR> 25/min
- Inability to complete sentences
Life-Threatening attack:
- PEFR < 33% predicted
- Silent chest
- Cyanosis
- Bradycardia
- Hypotension
- Confusion
- Coma
What Investigations are appropriate?
Acute:
- Peak flow
- Pulse Oximetry
- ABG
- CXR (to exclude other diagnoses)
- FBC, CRP, U&Es (raised WCC if infective exacerbation)
- Blood and sputum cultures
Chronic:
- Peak flow monitoring (often shows diurnal variation)
- Pulmonary function tests
- Bloods: check Eosinophilia, IgE lvel, Aspergillus antibody titres
- Skin prick tests (identify allergens)
What is the Management for Acute Asthma?
- ABCDE; resuscitate
- Monitor O2 sats, ABG and PEFR
- High flow O2
- Salbumatol nebulizer (5mg, initially continuously, then 2-4hr)
- Ipratropium bromide (0.5mg QDS)
- Steroid therapy (100-200mg IV hydrocortisone, followed by 40mg oral prednisolone for 5-7days)
- No improvement => IV Magnesium sulphate
- Consider IV aminophylline infusion
- Consider IV salbutamol
- Anaesthetic help if patient is tiring
Note: a normal PCO2 is a bad sign during an attack (they should hyperventilating so it should be low) - A normal PCO2 suggest patient is fatiguing
- Treat underlying cause e.g. infection
- Give antibiotics if infective exacerbation
- Monitor electrolytes closely because bronchodilators and aminophylline causes a drop in K+
- Invasive ventilation may be needed in severe attack
When criteria should be met before a patient is discharged?
- PEF >75% predicted
- Diurnal variation <25%
- Inhaler technique checked
- Stable on discharge medication for 24hr
- Patients owns a PEF meter
- Patient has steroid and bronchodilator therapy
- Arrange follow-up
What is the management plan for Chronic Asthma?
Step 1:
- Inhaled short-acting beta-2 agonist used as needed
- If needed >1 a day -> step 2
Step 2:
- Step 1 + regular inhaled low-dose steroids (400mcg/day)
Step 3:
- Step 2 + long-acting beta-2 agonist (LABA)
- If inadequate control, increase steroid dose (800/mcg/day)
- If no response to LABA, stop it and increase steroid dose
Step 4:
- Increase inhaled steroid dose (2000 mcg/day)
- Add 4th drug (e.g. leukotriene antagonist, slow-release theophylline or beta-2 agonist tablet)
Step 5:
- Add regular oral steroids
- Maintain high-dose oral steroid
- Refer to specialist care
Advice: proper inhaler technique, explain importance of PEF monitoring, avoid provoking factors
What are the complications of Asthma?
- Growth retardation
- Airway remodelling
- Chest wall deformity (e.g. pigeon chest)
- Recurrent infections
- Pneumothorax
- Respiratory failure
- Death
What is the prognosis of Asthma?
- Most children improve with age
- Adult asthma tends to be chronic
