Asthma Flashcards
Definition
Chronic inflammatory airway disease characterised by variable reversible airway obstruction, airway hyper-responsiveness and bronchial inflammation
Risk factors (genetic)
o Family history
o Atopy (tendency for T lymphocytes to drive production of IgE on exposure to allergens)
Risk factors (environmental)
o House dust mites o Pollen o Pets o Cigarette smoke o Viral respiratory tract infections o Aspergillus fumigatus spores o Occupational allergens
Epidemiology
· Affects 10% of children
· Affects 5% of adults
· Prevalence appears to be increasing
Presenting symptoms
· 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
· Check for history of atopic disease (e.g. allergic rhinitis, urticaria, eczema)
Signs on physical examination
· Tachypnoea · Use of accessory muscles · Prolonged expiratory phase · Polyphonic wheeze · Hyperinflated chest
Investigations (acute)
o Peak flow o Pulse oximetry o ABG o CXR - to exclude other diagnoses (e.g. pneumonia, pneumothorax) o FBC - raised WCC if infective exacerbation o CRP o U&Es o Blood and sputum cultures
Investigations (chronic)
o Peak flow monitoring - often shows diurnal variation with a dip in the morning
o Pulmonary function test
o Bloods - check:
· Eosinophilia
· IgE level
· Aspergillus antibody titres
o Skin prick tests - helps identify allergens
Management plan (acute)
o ABCDE o Resuscitate o Monitor O2 sats, ABG and PEFR o High-flow oxygen o Salbutamol nebulizer (5 mg, initially continuously, then 2-4 hourly) o Ipratropium bromide (0.5 mg QDS)
o Steroid therapy
· 100-200 mg IV hydrocortisone
· Followed by, 40 mg oral prednisolone for 5-7 days
o If no improvement –> IV magnesium sulphate
o Consider IV aminophylline infusion
o Consider IV salbutamol
o Anaesthetic help may be needed if the patient is getting exhausted
o 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
o Treat underlying cause (e.g. infection)
o Give antibiotics if it is an infective exacerbation
o Monitor electrolytes closely because bronchodilators and aminophylline causes a drop in K+
o Invasive ventilation may be needed in severe attacks
Management plan (chronic)
o Start on the step that matches the severity of the patient’s asthma
o STEP 1
· Inhaled short-acting beta-2 agonist used as needed
· If needed > 1/day then move onto step 2
o STEP 2
· Step 1 + regular inhaled low-dose steroids (400 mcg/day)
o 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)
o STEP 4
· Increase inhaled steroid dose (2000 mcg/day)
· Add 4th drug (e.g. leukotriene antagonist, slow-release theophylline or beta-2 agonist tablet)
o STEP 5
· Add regular oral steroids
· Maintain high-dose oral steroids
· Refer to specialist care
Management plan (advice)
o Teach proper inhaler technique
o Explain important of PEFR monitoring
o Avoid provoking factors
Possible complications
· Growth retardation · Chest wall deformity (e.g. pigeon chest) · Recurrent infections · Pneumothorax · Respiratory failure · Death
Prognosis
· Many children improve as they grow older
· Adult-onset asthma is usually chronic
Precipitating factors
o Cold o Viral infection o Drugs (e.g. beta-blockers, NSAIDs) o Exercise o Emotions
Signs on physical examination (severe attack)
o PEFR < 50% predicted
o Pulse > 110/min
o RR > 25/min
o Inability to complete sentences
