Asthma Flashcards
Impact
315 million adults worldwide
340 000 deaths/year
5.4 million being treated in UK
3 people die from asthma attach each day in UK
NHS spends £1 billion each year
2017: 1484 people died in UK - 50% higher death rate than EU
Presentation
Commonly presents in childhood/middle age
50% children with mild asthma will be symptom free by age 21
70% children with persistent asthma will have symptoms into adult life
If starts in adulthood - likely to persist
Airflow Obstruction
Bronchoconstriction - mast cells
Bronchial secretions and plugs of mucus - inflammation
Oedema of bronchial wall - inflammation
Inflammatory Cascade
Allergen -> antigen presenting cell -> Th2 -> B cell/plasma cell -> mast cell/basophil OR from Th2 -> eosinophil -> histamine -> allergic asthma
Symptoms and Triggering Factors
Cough, wheeze, breathlessness, chest tightness
Occurs in episodes with diurnal variability - worse at night/early morning.
Allergens, respiratory infections
Change in temp, exercise, cold air, emotion/stress
Food additives, reflux, air pollution, tobacco
Medication: aspirin, ibuprofen, beta blockers
Diagnosis
History (past medical, family, social), symptom free periods, possible alternative diagnosis (COPD)
Physical examination
Tests done: Peak flow monitoring, spirometry, chest X-ray, increased eosinophils in blood - blood test, fraction exhaled nitric oxide (FeNO)
Fraction exhaled nitric oxide - FeNO
Measure of eosinophilic inflammation in airways
Monitors treatment and compliance
Positive test (>40ppb) supports diagnosis of asthma
Test of Lung Function
Airway obstruction: FEV1/FVC ration <70%
PEFR monitoring - 20% diurnal variation
Reversible: with bronchodilators - 15%, 200mls improvement in FEV1
Management - Long Term
Non-pharmacological: smoking cessation, weight reduction, pollution
Inhaled corticosteroids: eg beclometasone, fluticasone
Inhaled Long Acting Beta2 Agonsist: must be in combination with ICSs - e.g. formoterol, salmeterol
Oral Treatment:oral leukotriene antagonist montelukast, oral theophyllines, in patients with poorly controlled asthma
Management - Short Term
SABA - salbulamol, terbutaline as inhaler/nebuliser
Maintenance & Reliever Therapy (MART): LABA formoterol has short onset of action (equivalent of salbutamol).
ICS/LABA combinations - as relievers & preventers
Patients can take additional doses for 2-3 days
Address and treat inflammatory aspect with both
2 Different Inhaler Devices
Dry Power Inhalers: activated by inspiration - powdered drug dispersed into particles
Pressurized Metered Dose Inhalers: drug dissolved in a propellant hydroflurocarbons under pressure - valve system releases a metered dose
Consider: side effects, cost, where patients are in treatment
Very Specialised treatment
Monoclonal antibodies
Anti-IgE injections (omalizumab)
Anti IL-5 treatment (mepolizumab)
Acute Severe Asthma
PEFR: 33-50%, breathless
Respirations > 25 breaths/minute
Pulse > 110 breaths/min
Life threatening: SpO2 < 92%, silent chest, cyanosis, feeble resp effort, hypotension, arrythmia
Management of Acute Severe Asthma
Oxygen
Corticosteroids
Nebulised Bronchodilators (salbutamol & ipratropium bromide)
If poor response: IV MgSO4/IV aminophylline
Discharge from Hospital: discharge meds, inhaler technique checked, PEFR > 75% of best, treatment with oral & inhaled steroids + bronchodilators, follow ups scheduled