Week Two - Case One Flashcards
what are the three main characteristics of asthma
airflow limitation
airway hyper-responsiveness
inflammation of the bronchi
how many patients in the UK die a year from asthma
2000
what is associated with the inflammation of the bronchi
with infiltration by eosinophils, T cells and mast cells. there is associated plasma exudate, oedema, smooth muscle hypertrophy, mucus plugging and epithelial damage.
what often causes an asthmatic flare and what symptom does this bring
often flares up with viral infections which often causes a loud wheeze
who Is most likely to be affected before/after puberty
before puberty, boys are more likely to be affected
after puberty, girls are most likely to be affected
is asthma intrinsic or extrinsic
the disease can either be intrinsic (aka cryptogenic) where no causatory factor can be found, or extrinsic, where there is a definite external cause
when does intrinsic asthma often start
often starts in middle age, and is sometimes called late onset asthma.
no trigger can be identified
when does extrinsic asthma occur
in atopic individuals who have positive skin prick test results.
this type of asthma causes 90% of childhood cases, and 50% of adults with chronic asthma.
what is extrinsic asthma often accompanied by
eczema
how do non-atopic individuals develop asthma in later life
via sensitisation to occupational agents, aspirin, or as a result of taking Beta-blockers for hypertension or angina
what kind of reaction is extrinsic asthma
involves a type 1 hypersensitivity reaction to inhaled allergens
what other reaction happens with asthma
there is also a delayed phase reaction, type IV hypersensitivity which occurs hours-days after exposure
what does the term atopy describe
people who often have allergies/asthma/hayfever and where the trait runs in families
what gene is associated with airway hyper-responsiveness and airway remodelling
ADAM33
what gene is associated with increased IgE production
PHF11 gene
what antibodies do people have to many common allergens
IgE antibodies - these antibodies are present in 35% of the population
what is the hygiene hypothesis
this is a theory that states that growing up in a clean environment in the early years of life can cause atopy. if you grow up in a dirty environment and are exposed to various bacteria, this is thought to help direct your immune system away from recognising inert particles as allergens.
what are the allergens for asthma very similar to
very similar to the allergens that cause rhinitis.
what is rhinitis
is inflammation of the mucosal lining of the upper respiratory tract, particularly affecting areas near the nose
what can rhinitis cause
a constant runny nose
how can you test airway hyper-responsiveness
asking patient to inhale gradually increasing amounts of methacholine or histamine.
what is this test called
bronchial provovation test
what does this test induce
will induce transient airflow limitation in 20% of the population - and these are the patients that exhibit airway hyper-responsiveness
what are the features of non-atopic asthma
does not appear to be immunologically mediated - i.e there is not T cell involvement
associated with recurrent respiratory tract infection (viral)
skin tests are negative
bronchoconstriction due to airway hyper-responsiveness , not as much due to inflammation and leukocyte infliltration