Asthma Flashcards
what is asthma characterised by?
Asthma is characterised by increased reactivity of the trachea and bronchi to various stimuli, manifested by a widespread narrowing of the airways and bronchial inflammation which may vary IN SEVERITY either spontaneously or with therapy, and typically presents with wheeze and/or cough
what are 4 features of asthma?
- variable/ reversible
- chronic condition characterised by wheeze
- responds to treatment
- various triggers
what are 3 proven risk factors of asthma?
- ->genetic
- atopy- inherited tendency of IgE response to allergen (maternal atopy most significant)
- immune response genes (IL-4,IL-5,IgE) or airway genes (ADAM33) in combination with several environmental influences may appear to affect development of asthma
- ->occupational- enzymes/grains/drugs etc
- ->smoking - mother during pregnancy / grandmother effect (epigenetic modification of oocytes)
what are other non-proven risk factors of asthma?
- obesity (BMI links)
- diet
- reduced microbe exposure
- abnormal lungs
- -> multi-hit theory
what are some triggers of asthma?
cold air, exercise, perfume, smoke, pets, pollen
what are the main symptoms of asthma?
- wheezing attacks
- episodic dyspnoea
- chest tightness
- cough (paroxysmal/dry)
- sputum (occasionally)
what is it important to find out with the symptoms of asthma?
important to establish evidence of VARIABILITY
when does asthma get worse?
in the mornings/late at night
what are 3 signs of asthma?
- breathlessness on exertion
- polyphonic wheezes
- HYPEREXPANDED CHEST
what signs indicate that it is probably not asthma?
- clubbing
- crackles/crepitations
- dullness on percussion
- cervical lymphadenopathy
- stridor -indicates URT obstruction
- asymmetrical expansion
what do investigations for asthma look for ?
- airway obstruction
- variability of symptoms
- reversibility with treatment
what is the flow of events once spirometry is done?
if obstruction –> full pulmonary function testing –> check for reversibility with B-2-agonist –> reversibility with steroids
if normal spirometry–> peak flow monitoring –> bronchial provocation & NO
what is spirometry?
lung function test which is useful in assessing reversibility
what is FEV1?
how much air is expired in first second - proxy for airway diameter
what is FVC?
final total amount of air expired- proxy for lung volume
what is the FEV/FVC ratio when airways are obstructed?
<70%
what is the point of doing a full pulmonary function test once have spirometry results ?
to exclude COPD
what are the 2 pulmonary function tests done and what do they measure?
CO gas transfer - measures HOW EFFICIENT lungs are at exchanging gases
lung volume - measures total size of lung & how air is distributed through them
why do you give a beta-2-agonist and what is the expected outcome if asthma?
-To assess for reversibility
response:
baseline, 15 mins after 400mcg inhaled Salbutamol
baseline, 15 mins after 2.5mcg nebulised Salbutamol
what happens to reversibility outcomes if no bronchoconstriction or if severe bronchoconstriction?
no reversibility
what do you give after a beta-2-agonist (plus dose) and why?
Oral steroids - 0.6MG/KG prednisolone 14 days
- useful if obstruction but no reversibility/variability
- differentiates between asthma/COPD
- aslo give peak flow chart & meter
if spirometry is normal, what is the action taken?
peak flow meter given to monitor, done twice daily for 2 weeks
what is looked for in the peak flow meter readings ?
- any evidence of variability (diurnal, weekly, annually)
- overall variability of >20%
what are further specialist investigations which can be done?
- Bronchial provocation–> airway responsiveness to metacholine/histamine
- Exhaled NO- people with asthma have higher levels of NO in their breath
- CXR –> checking that there is no effusion, collapse, opacities etc
- skin prick testing/ total IgE (checking for atopy) - skin prick testing is placing an allergen under the skin and check for wheal and flare reaction
- FBC (eosinophilia)- atopy
- Arterial blood gas (P02/PC02)
how do you assess acute severe asthma?
- whether patient is able to speak
- HR- pulse
- respiratory rate
- oxygen saturation
what is the first step of treatment in asthma
oxygen if hypoxic
SABA - salbutamol (MDI/DPI)
what is the second step in treatment of asthma & when do you start it
ICS- buclamethasone, budesonide, FLUTICASONE
give any dose from 200-800mcg/day, however 400 good starting point.
Start when- on SABA 3 or more times a week, waking up 1 night a week or more, if required steroid for an acute exacerbation any time in past 2 years, if sub-normal exercise tolerance
what is the third step in treatment of asthma ?
add LABA = formeterol.
if control adequate = continue
if better but control still inadequate= continue LABA but increase ICS to 800mcg/day
if LABA not working = remove LABA and increase ICS to 800mcg/day & consider alternative therapies (leukotriene antagonist/SR theophylline)
what is step 4 in treatment of asthma?
increase ICS to 2000mcg/day and consider alternative therapies
- leukotriene receptor antagonist (zafirlukast)
- theophylline (WEAK bronchodilator & many side effects)
what is step 5 in treatment of asthma?
- add DAILY steroid TABLET
- continue taking ICS at 2000mcg/day
- refer to specialist
what is the treatment regimen in acute (mild/moderate) asthma?
- oral steroids (prednisolone 7 days)
- SABA (every 2 hours)
what is the treatment regimen in acute (severe) asthma?
hospitalisation, oral/IV steroids, nebulised bronchodilators, antibiotics etc
what is the main difference between chronic and acute asthma treatment ?
chronic = inhaled steroids acute= oral steroids
what are the 2 things to always remember about LABA
- never take without ICS
- use FIXED DOSE inhaler
