obstructive lung disease Flashcards
(54 cards)
define asthma
Lung problem characterised by chronic inflammation which causes structural changes which leads to reversible airflow limitations
heterogenous condition that affects children and adults
what are risk factors for asthma?
dust, mould, tobacco smoke, chemicals, animals, pollen, air pollution, medicines, physical exercise, cold air, stress, viruses
how does chronic asthma impact airways?
o Thickening of the basement membrane
o Airway smooth muscle hypertrophy (increase in volume)
o Leukocyte infiltration
o Goblet cell hyperplasia (increase in numbers)
o Mucus hypersecretion leads to cough in people with asthma
why do people with asthma have a cough?
mucus hypersecretion
explain how eosinophilic asthma occurs
- Inhaled allergens cause cross linking of surface bound IgE on mast cells
- mast cells release several bronchoconstrictor mediators e.g. histamine
- Dendritic cells present the allergen as an antigen to Th2 cells and activate them
- Th2 activation leads to release of inflammatory mediators
in eosinophilic asthma, what inflammatory mediators are released and what do they do?
- IL-4, IL-13 –> stimulate B cells to synthesise more IgE
- IL-5 eosinophil activation
- IL-9 mast cell proliferation
what are the symptoms of asthma
• Cough, breathing difficulty, chest pain, shortness of breath, allergens, feeling tired
define wheezing
a continuous, high pitched musical sound coming from the chest
what is an asthma diagnosis based on?
- based on previous + current medical history + lung function tests
- episodic nature of symptoms e.g. asthma attacks instead of symptoms alone
- Looking for patients who present with; wheeze, cough, breathlessness, chest tightness
in a clinical assessment of someone with the symptoms of asthma, what things are you looking for to make a diagnosis?
o Recurrent episodes of symptoms
o Symptom variability
o Absence of symptoms of alternate diagnosis
o Recorded observation of wheeze
o Personal history of atopy
o Historical record of variable PEF or FEV1
what is PEF?
peak expiratory flow
maximal flow rate
describe the normal curve in a flow-volume graph
initial exhalation is rapid and fast. Breathe out until they hit the residual volume and can’t breathe out anymore.
what FEV1/FVC ratio does someone with asthma or COPD have?
<70%
what spirometry result would increase the probability of asthma?
Obstructive spirometry with positive bronchodilator reversibility increases the probability of asthma
what are the 3 main demographics that affect asthma and why?
age, gender and height
o Taller you are, the greater your lung capacity
o As you get older, your lung function declines
o Post-puberty, males have larger lung capacities than women
o Ethnicity also has an effect
what is the result of a positive BD reversibility test in adults?
Adults: FEV1 improvement ≥12% and ≥200 ml as a positive test
what is the result of a positive BD reversibility test in children?
FEV1 improvement ≥12% as a positive test
how many attempts should be done with PEF?
3
what is PEF used for?
Best used to provide an estimate of variability of airflow from multiple measurements made over at least 2 weeks
what PEF result increases the likelihood of asthma?
> 20%
what risk factors cause a greatly increased risk of asthma?
- a history of previous asthma attacks
- persistent asthma symptoms
what risk factors cause moderately increased risk of asthma?
- suboptimal drug regimen
- comorbid atopic/allergic disease
- low-income family
- vitamin d deficiency
what risk factors cause slightly increased risk of asthma?
younger age
exposure to environmental tobacco smoke
obesity
low parental education
what risk factors cause no increased risk of asthma?
gender
urban residence
