Asthma (Resp)* Flashcards
(C) Need to do paediatric area of this
Define Asthma
Asthma is a chronic respiratory condition characterized by recurrent episodes of airflow obstruction caused by bronchial hyper-responsiveness, and airway inflammation.
What are the risk factors of asthma?
Personal or family history of atopy (asthma, eczema, allergic rhinitis, allergic conjunctivitis)
Environmental/life factors - smoking, air pollution, occupational exposures, social dep
Antenatal factors such as smoking during preg, viral infection during preg (e.g. RSV)
Premature birth/low weight
Resp infections during infancy
Obesity
What are the clinical features of asthma in terms of symptoms?
Polyphonic wheeze, dyspnoea, cough, chest tightness. Symptoms show diurnal variation (worse at night/early morning)
What are the clinical features of asthma in terms of signs?
Expiratory wheeze on auscultation, reduced PEFR (esp early morning), tachypnoea, hyperinflated chest
What are the differential diagnoses of asthma?
Bronchiectasis, COPD, vocal cord dysfunction, GORD, churg-strauss syndrome
What are common triggers that cause the symptoms of asthma?
Cold air, exercise, pollution, cigarette smoke, allergens such as pollen/dust mites/or animal dander, irritants such as perfume/paints, infections, medications such as NSAIDs or beta blockers, occupational exposures such as chemical irritants, industrial dust
What is the aetiology of asthma?
Multifactorial - interplay of genetic, env and immuno factors.
How does the allergic asthma pathophysiology overall affect the airways (3)?
It is a type 1 hypersensitivity reaction and results in bronchoconstriction, excess mucus and airway oedema due to the inflammation created. Reduces airflow and so causes symptoms
Describe the first step of allergic asthma pathophysiology
Allergen sensitisation. 1) Allergen engulfed and processed by APC, presents to naive Th cell 2) th2 cell presents to B cell and releases il4 to B so IgE made which binds mast cell IgE receptor 3) Th2 also makes IL-5 - eosinophil prolif
Describe the second step of allergic asthma pathophysiology
Allergic asthmatic response. 1) allergen enters airway tissue 2) binds ige on mast cell - degranulation release IMs such as PGs and LTs 3)IMs cause bronchoconstriction, mucus, oedema. 4) Late/delayed response - allergen activates th2 in early response so il-5 recruits eosinophils where degranulate once in airway (ros, protelytic enzymes, LTs) (recruit and migrate takes time so late)
What are the investigation tests for asthma diagnosis?
FeNO (fractional exhaled nitric oxide) test - measures NO in exhaled breath and tf used to confirm eosino inflam. Positive = > 40 parts per billion
Spirometry measures vol of exhaled air, positive if FEV1/FVC < 70%
Bronchodilator reversibility (BDR) test - measures change in spirometry 15 mins after salbutamol inhaler. Positive if FEV1 is 12% or more (>12%)
What is an investigation test that may be used if diagnostic uncertainty of asthma?
Peak flow test diary ~ positive if variabilty greater than 20% (measures exhal speed)
What is the non-pharm management of chronic asthma?
Review inhaler technique and spacer device can be used to optimise med delivery
Smoking cessation
Yearly flu vaccine
Avoidance of triggers (allergens, certain meds)
Regular peak flow monitoring
What is the pharm management of chronic asthma in adults?
Step 1) Newly diagnosed - SABA for reliever. If infrequent wheeze and controlled by saba, then reliever therapy alone.
Step 2) If not controlled alone OR if symptoms 3 times a week or more or night waking then first line maintenance therapy is low dose Inhaled corticosteroid (ICS). Step 3) If still not then add LT receptor antag (LTRA). Step 4) add long acting beta agonist (LABA) and whether LTRA continued depends if beneficial/pt wants to. Step 5) change ICS + LABA to MART (includes low dose ICS) Step 6) increase ICS to moderate dose, either by continuing MART or by going back to seperate inhalers (ICS + LABA) Step 7) Can offer High ICS (offered as fixed dose regimen, not mart regimen), or additional drug e.g. LA musc recep antag, or seek advice from asthma expertise HC professional
Summary of steps of chronic asthma management?
Step 1) SABA Step 2) SABA + low ICS Step 3) SABA + low ICS +LTRA Step 4) SABA + low ICS + LABA +/- LTRA Step 5) SABA + MART(low ICS) +/- LTRA Step 6) SABA + MART (mod ICS) +/-LTRA OR SABA + mod ICS + LABA +/- LTRA Step 7) Can offer High ICS (offered as fixed dose regimen, not mart regimen), or additional drug e.g. LA musc recep antag, or biologics
