Asthma Flashcards
What is asthma
Chronic inflammatory airway disease characterised by intermittant airway obstruction and hyperactivity
Disease of small airways with variable expiratory airflow limitation
Inflammation is usually reversible
What type of reaction is asthma initally and then what does it become
Initally asthma is a type I hypersensitivity reaction
Late phase asthma is a type IV hypersensitivity reaction
Describe type I sensitivity reaction in asthma
First exposure of allergen causes immune response resulting in IgE production which implants itself onto mast cells and basophils
Re-exposure of allergen causes cross-linking of IgE on mast cells/basophils resulting in hyper-sensitivity reaction causing degranulation
Histamine and leukotrienes are released which cause bronchoconstriction while other mediators cause brochoconstriction and inflammation
This causes airway narrowing
How is airway narrowing caused in asthma
Airway smooth muscle - hyperresponsiveness, constriction and thickening
Sub-epithelial inflammation and fibrosis - basement membrane may thicken
Mucus hypersecretion and imparied mucus clearance
Increased eosinophils and/or neutrophils in airway lumen
What are some symptoms of asthma
Cough - dry, nocturnal
Wheeze - audible or on examination
Chest tightness
Breathlessness
Has a peak pattern
Name some precipitating factors of asthma
Allergens
Dust
Cigarette smoke
Cold weather
Exercise
Infection
Aerosols
Emotional distress
What does examination of an asthmatic patient reveal
Increased resp rate
Raised pulse
Low O2 sats
Wheeze
Atopy
Along with history, what is used in diagnosis of asthma
Peak flow meter - compare to predicted PEF for that person
Volume-flow graph - look for scalloping and reduced maximal expiratory flow
Volume-time graph - look for shallow gradient and low FVC
Describe the stepwise management for adults with asthma
Give short acting beta-2 agonist when needed
- Give low dose inhaled corticosteroid
- Give long lasting beta-2 agonist, e.g. salmetrol
- If LABA not working or is inadequate, can:
- Increase dose of ICS and either remove LABA or continue LABA depending on response to LABA
- Consider another therapy option
What are the types of inhalers
Blue - reliver. Short acting Beta-2 agonist
Brown - preventer. Inhaled corticosteroid
Combined steroid and LABA can be purple or another colour depending on the dose
What are the symptoms of severe asthma
Patient cannot complete full sentences
Has wheeze
O2 sats low but usually ≥92%
Tachypnoea - RR≥25
Tachycardic - BMP ≥ 110
Decreased peak flow - 33-50% of expected
What are the symptoms of life threatening asthma
Appear exhausted
Silent chest
No wheeze
Drowsy or tired
Cyanosed
Hypotensive and bradycardic
O2 sats < 92%
Cannot do peak flow - PEF < 33%
What is the treatment of acute asthma
O2
Short acting Beta-2 agonist
Steroids
Admit
Consider other medications
Consider CXR to rule out pneumothorax
