Asthma has a prevalence of 5.8% in the UK and is responsible for 1500 deaths annually.
Diagnosis
- Features that increase the probability of asthma:
- Wheeze, breathlessness and cough, particularly if
- Worse at night/early morning
- Occur in response to exercise, allergens, cold air, aspirin or beta blockers
- Family or personal history of atopy
- Widespread wheeze on auscultation
- Otherwise unexplained low FEV1 or PEF
- Otherwise unexplained peripheral blood eosinophilia
- Features that lower the probability of asthma:
- Prominent dizziness/light-headedness
- Chronic productive cough in absence of wheeze or breathlessness
- Voice disturbance
- Significant smoking history
Management
- If high probability of asthma – trial of treatment
- If intermediate probability – perform spirometry
- FEV1/FVC <0.7 – trial of treatment
- FEV1/FVC >0.7 - consider referral to specialist
- Low probability – consider referral to specialist
An increase of PEF >15% from baseline or increase of FEV1 > 400mls following a trial of treatment supports the diagnosis of asthma
Treatment
Chronic asthma
- Step 1:
- Inhaled short-acting beta 1 agonist PRN
- Step 2:
- Step 1 + inhaled steroid
- Step 3:
- Step 2 + long-acting beta 2 agonist
- If control still inadequate consider
- Stopping long-acting beta 2 agonist if no response
- Increasing inhaled steroid
- Trial of leukotriene receptor antagonist or SR theophylline
- Step 4:
- Step 3 + Further increase of inhaled steroid
- Addition of leukotriene receptor antagonist or SR theophylline or beta 2 agonist tablet
- Step 5:
- Step 4 + oral steroid
Acute asthma attacks
- Assement of severity of asthma
- Acute severe
- Any one of
- PEF 33-50% best or predicted
- Respiration rate ≥ 25/minute
- Heart rate ≥ 110/minute
- Inability to complete sentences in one breath
- Life-threatening
- Any one of
- PEF <33% best or predicted
- SpO2 < 92%
- PaO2 < 8 kPa
- Normal PaCO2
- Silent chest
- Cyanosis
- Poor respiratory effort
- Arrhythmia
- Exhaustion, altered conscious level
- Near fatal
- Raised PaCO2 and/or requiring mechanical ventilation with raised inflation pressures
- Treatment of acute severe asthma
- Oxygen
- Nebulised salbutamol
- Nebulised ipratropium bromide
- Prednisolone 40-50mg od – continue for at least 5 days or until recovery
- Consider single dose of IV magnesium sulphate
- Admit patients:
- With any feature of life threatening or near fatal attack
- Any feature of severe attack persisting after initial treatment
- Patients whose peak flow is >75% predicted or best one hour after initial treatment may be discharged from ED unless there are other indications for admission
- If patient is admitted, prior to discharge patient should:
- Have been on discharge medication for 12-24 hours
- Have PEF >75% predicted or best and PEF diurnal variability <25%
- GP follow up arranged within 2 working days
- Respiratory clinic follow up within 4 weeks
Small print gem: female gender is a risk factor for persistence of asthma from childhood to adulthood.
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