9a. Clinical features of Asthma in Adults Flashcards
Define Asthma
A disease characterised by an INCREASED RESPONSIVENESS of trachea and bronchi to various stimuli and manifested by a WIDESPREAD NARROWING of airways that CHANGES IN SEVERITY either spontaneously or as a result of therapy
What is the prevalence of Asthma in children?
10-15% M>F
What is the prevalence of Asthma in adults?
5-10% F>M
How many people are receiving asthma treatment?
5.4 million (1.1 million children, 4.3 million adults)
How many deaths per annum?
~1000
In which activity is asthma, most limiting?
Running 25-30%
What is it also limiting in?
Sport Stairs Pets DIY Gardening Pub Walking Sleeping
In the UK what is the statistics for admissions, bed days and GP consultations?
67,000 admissions, 220,000 bed days, 4.1 million GP consultations
How much does it cost the NHS annually?
£2,349m
What is the trend in asthma cases over the past few decades?
Rapid increase in the amount of cases
What are the proven risk factors for asthma?
Genetic
Occupation
Smoking
What is the Genetic risk factor?
Atopy
- Inherited tendency to IgE response to allergens
- Asthma, eczema, hayfever, food allergy
- Markers, skin prick tests, IgE
- Strongest risk factor: personal, familial atopic tendency
- Maternal atopy most influential (3x father)
- Linkage studies, two groups of genetic associations:
1) immune response genes; IL-4, IL-5, IgE
2) airway genes; ADAM33
What is the Occupational risk factor?
- Underestimated (10-15% of adult onset asthma)
- Interactions with smoking & atopy
Isocyanates = twin pack paints Colophony = welding solder flux Laboratory animals = rodent urinary proteins Grains = wheat proteins, grain mites Enzymes = subtilisin, amylase Drugs = antibiotics, salbutamol Crustaceans = prawns, crabs
What is the Smoking risk factor?
Maternal smoking during pregnancy v FEV1 ^ Wheezy illness ^ Airway responsiveness ^ asthma , ^ severity
‘Grandmother effect’
Mother smoked - 1.5 (1.0-2.3)
Maternal grandmother smoked - 2.1 (1.4-3.2)
Mother & Maternal grandmother smoked - 2.6 (1.6-4.5)
What is are possible risk factors for Asthma?
Obesity
Diet
Reduced exposure to microbes/microbial products
Indoor pollution: chemical household products
What is the Obesity risk factor?
Body mass index positively associated with
- asthma
- wheezing
- airway hyperractivity
What is the Reduced exposure to microbes/microbial products risk factor?
Children born on farms less likely to develop asthma
Greaterexposure to microbes/microbial products on farm
- endotoxin
- glucans
- extracapsular polysaccharide
Microbial diversity appears to be important in reducing the risk of asthma and allergy
What is the Indoor pollution risk factor?
Volatile organic compounds, formaldehyde, fragrances
Cleaners at increased risk of asthma OR 1.97 (1.33 – 2.92)
Adults who use sprays
weekly 1.49 (1.12-1.99) times more likely to be asthmatic
4 days/wk 2.11 (1.15-3.89) times more likely to be asthmatic
Mothers using sprays during pregnancy, children asthma
What are environmental allergens?
House dust mite
Cat
Grass Pollen (Timothy grass)
Exposure does not initiate/cause atopy/asthma, factors associated with affluence increase the likelihood of sensitisation to local allergens
What are the clinical aspects of Asthma?
Trying to differentiate from other causes of wheeze
- Localised airway obstruction, inspiratory stridor, tumour, foreign body
- Generalised airflow obstruction
- asthma (reversible AFO)
- COPD (irreversible AFO)
- bronchiectasis
- bronchiolitis
- Cystic Fibrosis
What are the Symptoms commonly associated with asthma but not solely associated?
Wheeze Shortness of breath (dyspnoea) Chest Pain Paroxysmal dry cough Sputum (occasional)
What is most important for making an asthma diagnosis?
History
What are the triggers?
Exercise Cold air Smoke perfume URTI's Pets Tree Grass pollen Food Aspirin
What are evidence of variable symptoms?
Triggers Daily variation (nocturnal/early morning) Weekly variation (occupation, better at weekends & holidays) Annual variation (environmental allergens)
