Things you should know about asthmawhat is asthma?- asthma is chronic inflammatory disorder of airways characterized by bronchial hyperresponsiveness leading to widespread bronchoconstriction.
-asthma is reversible
REMEMBER: airway narrowing and airway hyper-responsivenessFactors which cause asthma- host factors - atopy
- environment factor - allergen, infection, air pollution, smoking, diet etc
Mechanism of asthma:inflammation involving these cells and mediators result in airway hyper-responsiveness and asthma symptoms
- inflammatory cells (mast cell, eiosinophil and T lymphocytes)
- inflammatory mediators (chemokine, cytokine, cysteinyl leukotriene, histamine,NO, PG etc)
Airway narrowing due to:- airway smooth muscle constriction
- airway edema
- airway thickening
- mucus hypersecretion
airway hyper-responsiveness- err.. no need to know la..
special mechanism in asthmaacute exacerbation
- due to triggers
nocturnal symptoms
- due to circadian rhythm of hormones (epinephrine,cortisol,melatonin etc)
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Management depends on presentation - (acute/chronic) and
- severity
how to assess the severity?
- by clinical examination and ix (peak flow/spirometry)
classification of severity?
- intermittent
- mild/moderate/severe persistent
so, after patient already on treatment, you have to assess level of control. how u do that?
ask for:
-day symptoms
-night symptoms
-frequency of reliever tx
-limitation of activities
-lung function (PEF/FEV1)
-exacerbations (acute asthma attack)
Levels of control are:
-controlled
-partly controlled
-uncontrolled
Treatment of asthma
- reliever (bronchodilator)
- preventer (anti-inflammatory)
hmm.. what is bronchodilator?
-
B2-agonist (salbutamol, salmeterol)
-
anti-cholinergics (ipratropium bromide)
-
methylxanthines (oral theophylline, iv aminophylline)
-
cysteinyl-leukotriene antagonist (montelukast)
What is anti-inflammatory then?
-
steroid (beclomethasone, fluticasone, budesonide, oral prednisolone, iv hydrocortisone)
-
cromones (sodium cromoglicate)
now you know the medication, so now, how do you manage chronic asthma?
- ok, the principle is 'lowest dose possible to achieve control'
- so if not control, step up the medication
- this is call step-wise approach (step up/ step down)
1) SABA when necessary
2) SABA + low dose steroid
3) SABA + low dose steroid + LABA
4) SABA + moderate/high dose steroid + LABA
5) SABA + oral prednisolone (lowest dose)
then, what about exacerbation? what is it and how to treat?
ok, exacerbation is progressive SOB, chest tightness, cough or wheeze, characterized by reduction of expiratory flow.
it needs repeatitive SABA tx, early steroid tx and O2 supplementation
severity of exacerbation
- mild
- moderate*
- severe*
- respi arrest immenent*
*important
important facts1) GERD is 3 times more common in asthma
2) ~30% asthmatic adult have acute exacerbation due to aspirin/NSAID
3) in pregnancy, 1/3 become worse, 1/3 stable, 1/3 less severe
4) majority of asthma patients have hx of rhinitis. (30% rhinitis develop asthma)
5) near 70% polyps patient will develop asthma (almost 90% aspirin-intolerant have polyps)
6) viral (not bacteria) respi infection assoc with asthmatic symptom. virus include rhinovirus, para-influenza, influenza, coronavirus, adenovirus
