Asthma Flashcards
what is asthma
chronic, inflammatory airway disease. characterised by reversible airway obstruction, airway hyper-responsiveness and bronchial inflammation
aetiology
genetic factors and environmental factors
genetic factors causing asthma
family Hx and atopy
what is atopy
genetic tendency to develop allergic diseases such as allergic rhinitis, asthma and atopic dermatitis (eczema). this is a tendency of T cells to drive the production of IgE cells upon exposure to allergens
environmental factors causing asthma
house dust mites, pollen, pets, cigarette smoke, viral respiratory tract infections, aspergillus fumigatus spores (fungal infection) and occupational allergens
epidemiology
10% of adults affected, 5% of children affected.
prevalence is increasing
presenting symptoms
recent upper respiratory tract infection, dyspnoea, cough, expiratory wheeze and nasal polyposis (nasal polyps)
why may GORD be a risk factor for asthma
aspiration of particles may cause an upper respiratory tract infection
is the cough better in the morning or at night
cough in asthmatics is usually worse in the mornings and improves as the day goes along
precipitating factors
Cold Viral infection Drugs (e.g. beta-blockers, NSAIDs) Exercise Emotions
signs on physical examination
tachypnoea, patient uses accessory muscles to aid breathing, prolonged expiratory phase, polyphonic wheeze, hyper inflated chest
pulmonary function tests on severe attack
PEFR < 50% predicted
Pulse > 110/min
RR > 25/min
Inability to complete sentences
pulmonary function tests on life-threatening attack
PEFR < 33% predicted Silent chest Cyanosis Bradycardia Hypotension Confusion Coma
investigations in the acute setting
peak flow, pulse oximetry, ABG, CXR, FBC, CRP, Urea and Electrolytes, Blood and sputum cultures
investigations in the chronic setting
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
management (acute exacerbation)
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
why is normal pCO2 not a good sign
a patient in an asthma attack should be hyperventilating to get rid of the CO2 so a normal pCO2 indicates a deteriorating patient
Step 1 of chronic asthma management
Inhaled short-acting beta-2 agonist used as needed
If needed > 1/day then move onto step 2
step 2 of chronic asthma management
Step 1 + regular inhaled low-dose steroids (400 mcg/day)
step 3 of chronic asthma management
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 of chronic asthma management
Increase inhaled steroid dose (2000 mcg/day)
Add 4th drug (e.g. leukotriene antagonist, slow-release theophylline or beta-2 agonist tablet)
step 5 of chronic asthma management
Add regular oral steroids
Maintain high-dose oral steroids
Refer to specialist care
advice given to all asthmatic patients
teach proper inhaler techniques,
explain the importance of PEFR monitoring,
avoid provoking factors
possible complications of asthma
Growth retardation,
Chest wall deformity (e.g. pigeon chest),
Recurrent infections,
Pneumothorax,
Respiratory failure,
Death
prognosis in children
many children improve as they grow older
prognosis in adults
adult-onset asthma usually remains chronic
