Asthma Flashcards
What is asthma?
Asthma is a chronic inflammatory disease characterised by reversible airway obstruction
-Initial trigger releases inflammatory mediators
Lumen is reversibly folded due to smooth muscle bronchoconstriction and mucous hypersecretion
What are the cardinal features of asthma?
Atopy/Allergen sensitization
Reversible airflow obstruction
Airway inflammation
Eosinophilia
Type 2 lymphocytes
Wheeze/+- dry cough on exertion worse with colds and allergen exposure
What type of immune reaction is associated with asthma?
Type 2 immunity in allergic asthma
What cytokines are released in Asthma?
- IL-4 is a prominent immune mediator that supports the activation of B-cells into plasma cells to release IgE.
- IL-5 – Responsible for the maturation and release of eosinophils in the bone marrow.
- IL-15 is a central regulator in IgE synthesis, goblet cell hyperplasia, mucous hypersecretion, and airway hyperresponsiveness.
What roles does IL-5 have in asthma?
Maturation and releases of eosinophils in the bone marrow
What does role does IL-4 have in asthma?
A prominent lumen mediator that supports the activation of B-cells into plasma cells to release IgE
What effect does IgE have in asthma?
Mast-cell degranulation leading to the release of histamines and cytokines
What blood test is used to test for allergic sensitiation?
Blood test for specific IgE antibodies to allergens
only do once asthma diagnosis is confirmed
What are the risk factors for asthma?
Family history
Atopy (Tendency for T lymphocytes to drive production of IgE exposure
What environmental factors are associated with asthma?
- House dust mites
- Pollen
- Pets
- Cigarette smoke
- Viral respiratory tract infections
- Aspergillus fugimatus spores
- Occupational allergens
What is the presentation of asthma?
- Intermittent dyspnoea (SOB)
- polyphonic expiratory wheeze
- Cough (worse in the early morning and at night) + sputum. DIURNAL pattern of symptoms.
- Nasal polyposis
When is the asthma cough worse during the day?
Worse in early morning and at night
What is the pattern of symptoms for asthma?
Diurnal
What are the precipitating factors for asthma?
• Cold air – Induced bronchospasm
• Viral infection
• Drugs (E.g., beta-blockers, NSAIDs)
• Exercise
• Emotions
• Allergens – House dust mite, pollen, fur, pets – query.
• Smoking/passive smoking
• Pollution
• Ask if symptoms remit at weekend – may be triggered at work.
N.B: Check for history of atopic disease (Allergic rhinitis, urticaria, eczema).
What are the examination findings for asthma?
- Tachypnoea
- Use of accessory muscles
- Prolonged expiratory phase
- Polyphonic expiratory wheeze
- Reduced air entry
- nasal polyps
in acute asthma attacks –> Hyperinflated chest and hyper-resonant percussion notes
What defines a moderate asthma attack for PEFR?
PEFR > 50-75% predicted.
What parameters are associated with a severe asthma attack?
- PEFR 35-50% predicted
- Pulse > 110/min
- RR > 25/min
- Inability to complete sentences.
what parameters are associated with a near fatal asthma attack?
What parameters are associated with a life-threatening asthma attack?
- PEFR < 33% predicted
- Silent chest
- Cyanosis – PaO2 < 8 kPa, normal/high PaCO2 > 4.6 kPa, low pH <7.35.
- Bradycardia
- Hypotension
- Confusion
- Coma
What investigations are performed for the diagnosis of asthma?
Spirometry:
FEV1/FVC ratio <70% indicates airway obstruction
Bronchodilator reversibility (BDR) test is an imrpovement in FEV1 of 12% or more
Fractional exhaled nitric oxide (FeNO) - indicator of airway eosionphilia (but can be raised in conditions other than asthma)
Peak flow variability - diurnal variation in peak expiratory flow above 20%
(obstructive spirometry –> BDR –> FeNO –> asthma diagnosis)