Asthma and Respiratory Immunology Flashcards
How many people are currently receiving treatment for asthma?
5.4 million people in the UK
How many children are affected by asthma?
1.1 million children affected (approx. 3 in every class)
How many people die of an asthma attack every day in UK?
On average, 3 people die of an asthma attack every day in the UK
How much does the NHS spend on asthma?
NHS spends approx. £1billion annually treating asthma
What are the cardinal features of asthma?
- Wheeze +/- Dry cough – on exertion, worse with colds, with allergen exposure: most important
- Atopy / allergen sensitisation
- Reversible airflow obstruction
- Airway inflammation
What causes airway inflammation?
- Eosinophilia
* Type 2 - lymphocytes
Why do only some people who are sensitized develop disease (asthma)? What are these manifestations of asthma?
- genetic susceptibility and environmental exposures:
1. Allergy
2. Reversible airflow obstruction
3. Inflammation
What can genetic susceptibility lead to?
- Allergy
- Allergic disease
- Need genetic susceptibility for asthma not guaranteed with just an allergy
What are some environmental exposures?
- Allergen
- Infection that causes colds
- Pollution
What is the test for allergic sensitisation?
- Blood tests – for specific IgE antibodies to allergens of interest
- Total IgE alone not sufficient to define atopy - need specific IgE
What are the tests for eosinophilia?
- Blood eosinophil count when stable: >300 cells /mcl is abnormal during stable disease
- Induced sputum eosinophil count: >2.5% eosinophils is abnormal
- Exhaled nitric oxide
How is fractional concentration of exhaled nitric oxide (FeNO) used?
- quantitative
- non-invasive
- safe
- method of measuring airway inflammation
- an indirect marker of T2-high eosinophilic airway inflammation in asthma
- So high NO then supportive of asthma provided not on treatment with steroids
How else is FeNO used?
- aiding asthma diagnosis
- predicting steroid responsiveness and assessing adherence to inhaled corticosteroids
- So if started treatment but NO still sky high suggests not taking as NO very sensitive to steroids
What parts of clinical assessment is needed for asthma diagnosis?
- History & examination
2. Assess / confirm wheeze when acutely unwell
What are the objective tests for asthma diagnosis?
- Airway obstruction on spirometry - FEV1/FVC ration <0.7
- Reversible airway obstruction - Bronchodilator reversibility >12%
- Exhaled nitric oxide (FeNO) >35ppb (children), >40ppb (adults) - not on any treatment
What other condition other than symptoms suggestive of asthma to diagnose asthma in children and young people (aged 5to16)?
- FeNO level of 35ppb or more and positive peak flow variabilityor
- Obstructive spirometry and positive bronchodilator reversibility
- need two tests!
How do you reduce airway eosinophilic inflammation in the management of asthma?
- Inhaled corticosteroids (ICS)
2. Leukotriene receptor antagonists - reduce T2 inflammation
How do you manage acute symptomatic relief in management of asthma?
- Beta-2 agonists (smooth muscle relaxation)
2. Anticholinergic therapies (smooth muscle relaxation)
How do you manage severe asthma (steroid sparring therapies) in the management of asthma?
- Biologic targeted to IgE
- Anti-IgE antibody - Biologics targeted to airway eosinophils
- Anti-interleukin-5 antibody
- Anti-interleukin-5 receptor antibody