Asthma Flashcards
What is asthma characterised by?
Increased responsiveness of the trachea and bronchi to various stimuli and manifested by a widespread narrowing of the airways that changes in severity either spontaneously or as a result of therapy
Is bronchitis common?
Yes
Presentation of bronchitis
Loose rattly cough
Noisy breathing
Post tussive vomit (glut)
What is pertussis also known as?
Whooping cough
Pathology of bacterial bronchitis
Disturbed mucociliary clearance
Secondary infection following URTI
Causes of bronchitis
RSV
Adenovirus
Rhinovirus
Haemophilus
Pathology of asthma
Blocked airways because of mucus (luminal secretions) Increased irritability Bronchoconstriction Airway wall thickening Spontaneous or stimuli
Risk factors for asthma
Genetic
Occupation (painters, welding, labs, grains, bakers, antibiotics, salbutamol, crustaceans)
Smoking
Maternal smoking during pregnancy
Possible risk factors for asthma
Obesity
Diet
Reduced exposure to microbes/microbial products
Indoor pollution; chemical household products (volatile organic compounds, formaldehyde, fragrances, cleaning products)
Environmental allergens linked to asthma
House dust mite
Cats
Grass pollen
What is genetic atopy?
Inherited tendency to IgE response to allegens
Examples of atopy
Asthma
Eczema
Hay fever
Food allergy
What % of adult onset asthma is caused by occupation?
10-15%
What is higher BMI associated with in asthma?
Asthma
Wheezing
Airway hyperactivity
What is the allergen of house dust mite?
Protease in droppings
Types of onset of asthma
Infant onset Childhood onset Adult onset Exertional asthma Occupational asthma
Triggers of asthmatic symptoms
URTI (Rhinovirus in 75%) Exercise Allergen Cold air Emotion Menstruation Aspirin
What must be present for asthma to be diagnosed?
Wheeze
What children have asthma?
10 - 15%
M > F
What adults have asthma?
5 - 10%
F > M
What conditions can cause generalised airflow obstruction?
Asthma (reversible) COPD (irreversible) Bronchiectasis Bronchiolitis CF
Presentation of asthma
Wheeze
SOB at rest
Cough
Chest tightness/pain
Features of cough in asthma
Dry
Nocturnal
Exertional
Occasional sputum
What kind of symptoms must be present to diagnose asthma?
VARIABLE symptoms
- triggers
- daily variation (early morning/nocturnal)
- Weekly variation (occupation, better at weekends and holidays)
- annual (environmental holidays)
When is asthma generally worse?
Morning
Night
PMH associations of asthma
Childhood asthma
Eczema
Hayfever
Drugs associated with asthma
Aspirin
Complicance B blockers
NSAIDs
What would you ask about FH of asthma?
Atopic disease
Asthma
What social history would be associated with asthma?
Smoking
Pets
Occupation
Psychosocial
Possible signs of asthma
Breathlessness on exertion
Hyperexpanded chest
Polyphonic wheezes
What would a dull percussion note on examination indicate?
Lobar collapse
Effusion
What would crepitations on examination indicate?
Bronchiectasis
CF
Alveolitis
LVF
What is used in clinic to asses lung function in asthma?
Spirometry
How does spirometry work?
Deep breath in and blow out hard and fast
Best of 3 readings
Compare off chart
What is FEV1?
Forced expiratory volume in 1 second
What does FEV1 essentially measure?
Airway diameter
What does FVC essentially measure?
Lung capacity
If there is an obstructed picture, what should be done and what is involved?
Full pulmonary function testing - Helium dilution - CO gas transfer Reversibility to bronchodilator Reversibility to oral corticosteriods
Interpretation of reversibility to bronchodilator
15 mins post 400ug inhaled salbutamol
15 mins post neb 2.5-5mg salbutamol
Significant reversibility; difference in FEV 1 > 200ml and change in FEV1 > 15% baseline
What could cause no reversibility?
No bronchoconstriction
Severe bronchoconstriction
What does response to oral steroids separate asthma from?
COPD
What variability is present in asthma?
Morning/nocturnal dips
Decline over weeks/days
Variability >20% / highest
Diagnosis of occupational asthma
Suspicion from work related symptoms
Working with recognised occupational sensitizer
Serial peak flow readings (2 hourly best; 5 per day minimum)
Antibodies
+ve response to colophony
Useful investigations in asthma
CXR - hyperinflated - hyperlucent Skin prick testing (atopic status) Total and specific IgE (atopic status) FBC - eosinophilia (atopy)