What is asthma?
A chronic disorder characterised by airway wall inflammation and re-modelling
What kind of pulmonary disorder is asthma?
Reversible airflow obstruction
What happens to airways in asthma?
- Thickened smooth muscle
- Thickened basement membranes
What is the pathological process in asthma?
Triggers cause airway smooth muscle to contract
What is the result of airway smooth muscle contraction in asthma?
- Reduced airway radius
- Increased resistance
- Reduced airflow
Describe the prevalance of asthma
- Increasing in prevalence
- More common in developed world
- Increasing in populations who move from developing to developed countries
How many people in the UK currently recieve treatment for asthma?
- 1.1 million children
- 4.3 million adults
What are the potential causes of asthma?
- Genetic risk
- Sensitisation to airborne allergens
- Hygeine hypothesis
What airborne allergens are assoicated with asthma?
- House Dust Mite
- Air pollution
- Tobacco smoke (Pre/post-natal exposure, active)
What kind of diagnosis is asthma?
Why is asthma a clinical diagnosis?
There is no standard investigation of the type, severity, or frequency of symptoms, not of the findings on investigation
What is asthma defined as?
More than one of the symptoms of;
- Chest tightness
- Variable airflow obstruction
Of what nature is the wheeze in asthma?
- High pitched, expiratory sound
What is meant by polyphonic wheeze?
The wheeze is of variable intesity and tone
Where does the wheeze originate in asthma?
In the airways which have been narrowed be compression or obstruction
Of what nature is the cough in asthma?
- Often worse at night
- Exercise induced
What are the potential consequences of an asthmatic cough being worse an night?
- Lack of sleep
- Poor performance at school
What are the potential consequences of an asthmatic cough being exercise induced?
Decreased participation in activities
What does an asthma examination consist of?
What should be inspected when examining for asthma?
- General health
What are you looking for when inspecting the chest during an asthma examination?
- Scars and deformities
- Hyper-expansion (Barrel Chest)
What are you looking for when inspecting general health during an asthma examination?
- Can they speak?
What are you looking for on inspection of the room during an asthma examination?
What sign on percussion is indicative of asthma?
What sign on auscultation is indicative of asthma?
What tests are used to assess the condition of a patient suspected with asthma?
- Spirometry - Flow volume loop
- Allergy testing
- Chest X-rays
What will be shown on a flow volume loop with a patient with asthma?
- Low PEFR
- Low FEV1/FVC ratio
- >12% increase in FEV1 following salbutamol
Draw a flow volume loop illustrating;
- A normal person
- An asthmatic
- An asthmatic with salbutamol
How are allergen tests for asthma carried out?
Skin prick to aero-allergens, e.g. cat, dog, HDM, then assess blood IgE levels
Why are chest x-rays performed in patients suspected to have asthma?
To exclude other diseases, inhalation of foreign body, or a pneumothorax
What pathophysiological changes underlie the asthmatic condition
What cells are responsible for the inflammation in asthma?
- Mast cells
- Dendritic cells
What happens to mast cells in the asthmatic condition?
They are increased in number
What do mast cells do in asthma?
Release prostaglandins, histamine, etc.
Where are large numbers of eosionophils found in asthma?
In the bronchial wall and secretions
What is the role of dendritic cells in asthma?
Have a role in the initial uptake and presentation of allergens to lymphocytes
What is the role of lymphocytes in asthma?
T-helper lymphocytes (CD4) release cytokines that play a key part in the activation of mast cells
What phenotype is related to asthma?
Why is the Th2 phenotype related to asthma?
Because it favours the production of antibody production by the B lymphocytes to IgE
What gets remodelled in asthma?
- Basement membrane
- Smooth muscle
Why is the epithelium remodelled in asthma?
It gets stressed and damaged
What happens to remodelled epithelium in asthma?
There is a loss of ciliated columnar cells
What happens in remodelling of the basement membrane in asthma?
Deposition of collagen causes it to thicken
What happens in the remodelling of smooth muscle in asthma?
Hyperplasia causing thickening of muscle
Can asthma exacerbations occur spontaneously?
What are asthma exacerbations most commonly caused by?
- Lack of treatment adherence
- Respiratory virus infections associated with the common cold
- Exposure to allergen or triggering drug
Give an example of a drug that can trigger asthma?
What are the principles in treating asthma?
- Primary prevention
- Pharmacological management
What is the purpose of asthma education?
Educate patients to correctly regonise symptoms, to use their medication timely, use services appropriately, and to develop their own Personal Asthma Action Plan
What measures are taken in the primary prevention of asthma?
- Stop smoking
- Fresh air
- Reduce exposure to allergens/triggers
- Weight loss
What drugs are involved in the pharmacological management of asthma?
- Anti-inflammatory agents
What kind of drugs are ß2 adrenoagonists?
What is the purpose of the use of ß2-adrenoagonists in asthma treatment?
Short term relief
Give an example of a ß2 adrenoagonist used in asthma treatment?
What anti-inflammatory agents are used in the treatment of asthma?
What is the purpose of the use of corticosteroids in the treatment of asthma?