Asthma Flashcards
What is asthma?
A chronic inflammatory condition causing episodic exacerbations of bronchoconstriction.
What causes bronchoconstriction in asthma?
Hypersensitivity of the airways
What are triggers of asthma?
Extreme emotion Exercise Cold or damp air Night time Early morning Dust Infection
What are signs of asthma?
Only episodic constriction Diurnal variability (worse at certain times of day) Dry cough Wheeze SOB History of allergies - to food, hay fever Family history Bilateral widespread polyphonic wheeze
What are the BTS/Sign guidelines on diagnosis?
If theres a high suspicion of asthma - diagnose without testing.
If theres a moderate/low suspicion of asthma - carry out tests before diagnosing.
What are the NICE guidelines on diagnosing asthma?
Testing should be done before diagnosis:
Fractional exhaled nitric oxide
Spirometry with bronchodilator reversibility
What are further tests that can be done?
Peak flow variability - keeping a diary
Direct bronchial challenge test - with histamine or methacholine
What are the NICE guidelines for long term stepwise management of asthma?
- Short acting beta 2 agonist (salbutamol) - when required for wheezy episodes
- Inhaled low dose corticosteroid - regular
- Oral leyukotrine receptor antagonist (montelukast)
- Long acting beta2 agonist (salmeterol) - only continue if its having an effect
- Consider changing to maintenance and reliever therapy regime (MART)
- Increase inhaled corticosteroid to moderate dose
- Increase inhaled corticosteroid to high dose OR oral theophylline OR inhaled long acting muscatinic antagonist (tiptropium)
- Refer to a specialist
How do Beta 2 antagonists work?
bind to the B2 receptors on bronchial smooth muscle cells – causes relaxation of smooth muscle.
Effect is FAST and LOCALISED to the lungs.
Also bind to B2 receptors on immune cells – prevent release of inflammatory mediators.
How long do SABAs take to work?
take 5 minutes to work – last for 2-4hours – used in acute attacks.
How long do LABAs take to work?
for prophylaxis, take a long time to work – last for over 12hrs.
What are side effects of beta 2 agonists?
tachycardia, palpitation, muscle tremors, restlessness, insomnia.
How do muscarinic antagonists work?
bind to M3 muscarinic receptors on tracheal and bronchial smooth muscle – blocks acetylcholine from binding to the M3 muscarinic receptors – leading to reduced smooth muscle constriction.
What are the side effects of muscarinic antagonists?
tachycardia, dry mouth, restlessness, pupil dilation
What are examples of SABA?
Salbutamol
Abluterol
Terbutaline
