Theme 4: Lecture 7 - Asthma Flashcards
Definition of asthma
- Heterogeneous disease characterised by chronic airways inflammation
- Is a disease characterized by recurrent attacks of breathlessness and wheezing, which vary in severity and frequency from person to person. In an individual, they may occur from hour to hour and day to day.
What causes airflow obstruction
- Bronchoconstriction - contraction of the smooth muscle in the bronchial wall
- Bronchial secretions and plugs of mucus - due to inflammation of the bronchial wall
- Oedema of the bronchial wall - due to inflammation the lining mucosa of the bronchial wall
Atopy
- A form of allergy in which there is a hereditary or constitutional tendency to develop hypersensitivity reactions in response to allergens
- Tendency to form IgE antibodies to allergens (such as pollen, house dust mites or animals).
- Often associated hay fever or eczema in the personal or family history
What is asthma in young people usually linked to
Atopy
Symptoms and characteristics of asthma
- Cough
- Wheeze
- Breathlessness
- Chest tightness
- Occurs in episodes with periods of no (or minimal symptoms)
- Diurnal variability-so worse at night or early morning
Medications that trigger asthma
- Aspirin
- Ibuprofen
- Beta blockers
What do you need to make a diagnosis of asthma
- History is crucial-need more than one symptom
- Symptom free periods
- Past medical history (previous wheezing illness, hay fever, eczema), family history (of any atopic disease), and social history (occupation, pets) can provide clues
- Alternative diagnosis unlikely-what could these be?
- Physical examination may be normal except during an attack
What are the investigations for asthma that may be done by a GP
- Peak flow monitoring-twice day for 2 weeks
- Spirometry may show airflow obstruction, but may be normal between attacks
What are the investigations for asthma that may be done by the hospital
Skin prick or blood tests may confirm allergies
What are the investigations for asthma that may be done by the GP or hospital
- Chest X-ray often normal, but may show hyperinflation
- Increased eosinophil count in the blood
- Fraction exhaled nitric oxide (FeNO)
Tests of lung function
- Is there airflow obstruction? (FEV1/FVC ratio <70)
- Does it vary over time? (peak expiratory flow rate (PEFR) monitoring-20% diurnal variation worse at night/early morning)
- Is it reversible? (with bronchodilators)
Describe the FeNO (Fraction of exhaled nitric oxide)
- Measure of airways eosinophilic inflammation
- Performed on patients not on any treatment, a positive test (> 40ppb - parts per billion) supports diagnosis of asthma
- Can be done in GP and hospital clinics
- Can be used to monitor treatment/look at compliance
What is the long term non pharmacological management of asthma
- Smoking cessation
- Weight reduction
- Pollution-may provoke acute asthma or aggravate existing asthma but effects from allergens, smoking and infection more significant
ICS
Inhaled corticosteroids
LABA
Long acting beta 2 agonists
Name an inhaled corticosteroid
Beclometasone
Name an inhaled long acting beta 2 agonist (LABA)
Salmeterol
The pharmacological use of inhaled corticosteroids in control of asthma
- Key first line treatment in patients with asthma
- Supresses the inflammation response
- Long term