Asthma Flashcards
Asthma : Pathophysiology
- Exposure to allergen in the environment triggers an inflammatory response
- Causing smooth muscles of the bronchioles to constrict in response
- Reversible obstruction of the airway
Asthma : Risk factors
- Atopy - eczema, hay fever
- Hygiene hypothesis
- Family history - childhood asthma diagnosed before age 12 likely 2nd to genetic cause whereas adult asthma likely to be 2nd to environment
Asthma : Symptoms
- Cough - worse at night and early morning ‘diurnal’
- Chest tightness and breathlessness
- Wheezing
- Increased mucus production
Asthma : Diagnosis < 5
< 5 years }** Dx is based on clinical judgement **
- FHx of Asthma, atopy
- Clinically asthmatic symptoms
Asthma : Diagnosis - 5-16 years
- First line : Spirometry with bronchodilator reversibility.
If negative;
- Second line : FeNO test
Asthma : Diagnosis -> 16 years
Adults > 17 years = Spirometry (BDR) + FeNO for dx
Asthma : Spirometry results
Obstructive disease
1. FEV1 : Significantly reduced
2. FVC : Normal
- Pre bronchodilator : FEV1/FVC < 70%
- Post bronchodilator : FEV1/FVC improves 12% / 200mls or more
} Indicates + for Asthma due to reversibility
Asthma : FeNO test explanation
Definition : FeNO test measures the amount of NO exhaled in the breath
- Eisenophils are a type of white blood cells secreted in response to allergic reactions
- Eisenophils produce nitric oxide as a by product
- Level of inflammation correlates with the level of eisenophils hence the amount of NO exhaled.
Asthma : FeNO test - Asthma
FeNO results
* Adults >40 parts per billion (ppb) = positive for asthma
* Children > 35 parts per billion (ppb) = positive asthma
Asthma : NSAID therapy
Avoid NSAIDs e.g. Aspirin in patients with Asthma
MOA :
1. NSAIDs inhibit COX enzyme which produces prostaglandins
- Inhibition of COX results in increased production of leukotrienes which is an inflammatory chemical
- This triggers inflammation and bronchoconstriction in the lungs of asthmatic patients
Asthma : Mx : Step 1
Mx : Short acting beta agonist ‘SABA’
Escalate if;
If SABA used > 3x a week
Asthma : SABA
Short acting beta agonist ‘SABA’
- *MOA *: act on beta-2 adrenergic receptors on the smooth muscle of bronchioles and cause dilation of airways
- Indication : helps to relieve short term symptoms of chest tightness and wheezing
- Onset : within 15 minutes, lasts up to 4 hours
- Examples : Salbutamol, Terbutaline
5.* CI *: Avoid SABA and non cardio-selective beta blocker } bind to B2 in bronchioles
Asthma : Mx : Step 2
Step 2 - Add ICS
SABA + low dose inhaled corticosteroid (ICS)
Asthma : SE of inhaled steroids
- Oral/Pharyngeal thrush - ‘Oral candidiasis’
Asthma : Mx : Step 3
Step 3 - Add LTRA
SABA and low dose inhaled corticosteroid (ICS) + LTRA