Asthma Flashcards
Define asthma
Chronic inflammatory airway disease characterised by variable reversible airway obstruction, airway hyper-responsiveness and bronchial inflammation
Explain the aetiology/risk factors for asthma
Genetic Factors
Family history
Atopy (tendency for T lymphocytes to drive production of IgE on exposure to allergens)
Environmental Factors House dust mites Pollen Pets Cigarette smoke Viral respiratory tract infections Aspergillus fumigatus spores Occupational allergens
Summarise the epidemiology of asthma
Affects 10% of children
Affects 5% of adults
Prevalence appears to be increasing
Recognise the presenting symptoms of asthma
Episodic history
Wheeze
Breathlessness
Cough (worse in the morning and at night)
IMPORTANT: ask about previous hospitalisation due to acute attacks- this gives an
indication of the severity of the asthma
Precipitating Factors Cold Viral infection Drugs (e.g. beta-blockers, NSAIDs) Exercise Emotions Check for history of atopic disease (e.g. allergic rhinitis, urticaria, eczema)
Recognise the signs of asthma on physical examination
Tachypnoea Use of accessory muscles Prolonged expiratory phase Polyphonic wheeze Hyperinflated chest
Severe Attack PEFR < 50% predicted Pulse > 110/min RR > 25/min Inability to complete sentences
Life-Threatening Attack PEFR < 33% predicted Silent chest Cyanosis Bradycardia Hypotension Confusion Coma
Identify appropriate investigations for asthma
ACUTE Peak flow Pulse oximetry ABG CXR -to exclude other diagnoses (e.g. pneumonia, pneumothorax) FBC -raised WCC if infective exacerbation CRP U&Es Blood and sputum cultures
CHRONIC
Peak flow monitoring -often shows diurnal variation with a dip in the morning
Pulmonary function test
Bloods: check Eosinophilia, IgE level Aspergillus antibody titres
Skin prick tests - helps identify allergens
What is acute management of Asthma?
ABCDE
Resuscitate
Monitor O2 sats, ABG and PEFR
High-flow oxygen
Salbutamol nebulizer (5 mg, initially continuously, then 2 -4 hourly) Ipratropium bromide (0.5 mg QDS)
Steroid therapy 100-200 mg IV hydrocortisone
Followed by, 40 mg oral prednisolone for 5-7 days
If no improvement–> IV magnesium sulphate
Consider IV aminophylline infusion
Consider IV salbutamol
Anaesthetic help may be needed if the patient is getting exhausted
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IMPORANT: a normal PCO2 is a BAD SIGN in a patient having an asthma attack. This is because during an asthma attack they should be hyperventilating and blowing off their CO2, so PCO2 should be low. A normal PCO2 suggests that the patient is fatiguing.
Treat underlying cause
(e.g. infection)
Give antibiotics if it is an infective exacerbation
Monitor electrolytes closely because bronchodilators
and aminophylline cause a drop in K+
Invasive ventilation may be needed in severe attacks
DISCHARGE when: PEF > 75% predicted Diurnal variation < 25% Inhaler technique checked Stable on discharge medication for 24 hours Patient owns a PEF meter Patient has steroid and bronchodilator therapy
Arrange follow up
What is chronic management of asthma?
Start on the step that matches the severity of the patient’s asthma
STEP 1
Inhaled short-acting beta-2 agonist used as needed
If needed > 1/day then move onto step 2
STEP 2
Step 1 + regular inhaled low-dose steroids (400 mcg/day)
STEP 3
Step 2 + inhaled long-acting beta-2 agonist (LABA)
If inadequate control with LABA, increase steroid dose (800 mcg/day)If no response to LABA, stop LABA and increase steroid dose (800 mcg/day)
STEP 4
Increase inhaled steroid dose (2000 mcg/day)
Add 4th drug (e.g. leukotriene antagonist, slow-release theophylline or beta-2agonist tablet)
STEP 5
Add regular oral steroids
Maintain high-dose oral steroids
Refer to specialist care
Advice
Teach proper inhaler technique
Explain important of PEFR monitoring
Avoid provoking factors
Identify the possible complications of asthma
Growth retardation Chest wall deformity (e.g. pigeon chest) Recurrent infections Pneumothorax Respiratory failure Death
Summarise the prognosis for patients with asthma
Many children improve as they grow older
Adult-onset asthma is usually chronic
