Asthma Flashcards
how does the WHO define asthma?
– Recurrent episodes
– Variability
– Reversibile airways inflammation
– Bronchial hyper-responsiveness to external
stimuli
what is the pathophysiology of the early phase of asthma?
- Initiation of inflammatory cascade (early phase) – IgE
antibodies released - IgE leads to activation of mast cells
- Activation of mast cells lead to release of
leukotrienes, cytokines, histamine smooth muscle
constriction and inflammation
what is the pathophysiology of the late phase asthma?
T-cells, macrophages, eosinophils recruit ->
inflammation and bronchoconstriction (late phase)
what are the main causes/ triggers of asthma?
– Genetic links - not absolute
– House dust mite
– Animal allergens- e.g. cats
– Pollens e.g. grass, trees
– Infections - particularly viral
– Occupational agents in workplace
– Drugs
– Passive / current smoking
how do you confirm diagnosis of high probability asthma?
– Six week treatment trial of inhaled corticosteroids and SABA
– Assess response objectively (done as part of SCA)
* Baseline needed
* Assess patient status using a validated symptom questionnaire
(asthma control questionnaire)
* Perform objective lung function tests (spirometry OR peak
expiratory flow)
Improvements in symptoms and objective tests following
treatment trials strongly indicate asthma. Lack of improvements
suggest alternative diagnosis
what would a normal patients spirometry reading show?
- High forced vital capacity (FVC)
- High forced expiratory volume in one second (FEV1)
what would an obstructive patients spirometry reading show?
- Low forced vital capacity (FVC)
- Low forced expiratory volume in one second (FEV1)
what increases the probability of asthma in spirometry?
– Obstructive: FEV1/FVC <0.7
– Positive result: improvement in FEV1 of ≥ 12% with an increase in volume of 200ml
– Improvement in FEV1 of ≥ 400ml – strongly suggests asthma
what is a peak flow?
- Provides estimate in variability of
airflow based on level of inflammation
in lungs – different to spirometry! - Measures force an individual can
breath out with
how does the peak flow meter work?
- Patients have a baseline that is normal
for them but there are expected values
based on height, weight, age.
– More inflammation on lungs –
lower scores compared to baseline
– Less inflammation on lungs –
higher / normal scores compared
to baseline - We look for variability in readings over
a 2 week period to gauge diagnosis /
control of asthma
how do you preform a peak flow meter?
– Deep breath in
– Hold breath for two seconds
– Rapidly breathe out
– Record value
– Do this three times morning and night and record the best from each
Repeat this twice daily for two weeks
* Take an average of all “best” readings from daytime and evening
* Take the highest and the lowest readings and calculate express
these as a percentage of the average. A 20% difference between
these values strongly suggests asthma
what is complete control defined as?
– No daytime symptoms
– No night time awakening due to asthma
– No need for rescue medication
– No asthma attacks
– No limitations on activity including exercise
– Normal lung function
– Minimal side-effects from medication
what is the BTS approach to asthma?
- Start at the level most appropriate to initial severity
– For most individuals this is SABA PRN for relief of
symptoms and ICS BD for prevention of symptoms - Overall aim: Achieve early control reduce risk of
acute attacks and hospitalisation - Maintain control by:
– Increasing treatment
– Decreasing treatment
what is the drug treatment available for asthma?
- Relievers
– Bronchodilators: relax smooth muscle in walls of airways
– Salbutamol, terbutaline – SABAs (short acting beta agonists) - Preventers
– anti inflammatory drugs which reduce inflammation in the airways e.g. corticosteroids, leukotriene receptor
antagonists
– Bronchodilators: long acting beta agonists to provide
longer lasting relaxation of smooth muscles
when should you step up therapies?
– Asthma attack in the last 2 years
– Using inhaled SAB2A 3 times per week
or more
– Symptomatic 3 times per week or more
– Waking 1 night per week
– Asthma affecting daily activities
