asthma Flashcards
what is an obstructive airways disease
conditions that cause the narrowing of the large, medium-sized and small airways
what are examples of obstructive airway diseases
asthma, COPD and bronchiectasis
what do obstructive airway diseases result in
air trapping and hyperinflation
what does an obstructive airways disease look like in spirometry
↓ FEV1
↔ FVC
↓ FEV1/FVC < 70%
what is FEV1
forced expiratory volume in 1s
what is FVC
forced vital capacity
what type of disease is asthma
reversible obstructive airways disease
what is asthma caused by
inflammation, hyper-responsiveness and narrowing of the bronchial tree
where does asthma occur
in a susceptible individual secondary to a variety of stimuli
what are the characterisations of asthma
recurrent attacks of breathlessness and wheezing
what is the severity of asthma like
varies in severity and frequency from person to person
what is the diagnosis criteria for asthma
no consistent diagnostic criteria
what are some symptoms that can cause a diagnosis of asthma?
more than one wheeze, breathlessness, chest tightness and cough
variable airflow obstruction
what is the death rate like for people with asthma in the UK?
3-5 daily
where does airway inflammation occur in asthma
when a genetically susceptible individual with atopy is exposed to certain environmental factors
what is atopy
the tendency to produce high amounts of Immunoglobulin E (IgE) when exposed to small amounts of an antigen
what are features of atopic individuals
- Atopic individuals have a high prevalence of asthma, allergic rhinitis, urticaria and eczema
- Atopic individuals will demonstrate positive reactions to antigens on skin prick testing
what can cause airway inflammation
sensitisation of atopic individual
inhilation of allergen
what is the two parts of the two phase response
early reaction and late reaction
how long is the early reaction in asthma
20 min
how long is the late reaction in asthma
6-12 hours later
what regulates the inflammatory response in asthma
T-helper lymphocytes regulate the inflammatory response in asthma.
What do Th2 cells secrete in the response to asthma
Th2 cells secrete pro-inflammatory interleukins and stimulate the release of IgE antibodies by plasma cells.
What is the role of Th1 cells in the response to asthma
Th1 cells down-regulate the atopic response in asthma.
What happens when IgE antibodies bind to receptors on mast cells and eosinophils?
When IgE antibodies bind to receptors on mast cells and eosinophils, they stimulate the release of histamine, prostaglandins, and cysteinyl leukotrienes.
What is the effect of histamine, prostaglandins, and cysteinyl leukotrienes on the airways?
The effect of histamine, prostaglandins, and cysteinyl leukotrienes on the airways is bronchoconstriction within minutes.
What are the targets for therapies in asthma?
The targets for therapies in asthma are the mediators of histamine, prostaglandins, and cysteinyl leukotrienes.
What distinguishes asthma from COPD?
The reversibility of bronchoconstriction distinguishes asthma from COPD.
What is the late phase response in asthma?
The late phase response in asthma is the infiltration of the smooth muscle layer by eosinophils, basophils, neutrophils, monocytes, and dendritic cells.
What is the result of the late phase response in asthm
The result of the late-phase response in asthma is
patchy desquamation of epithelial cells, increased number of mucus glands,
goblet cell hyperplasia,
hypertrophy and hyperplasia of airway smooth muscle,
contraction of smooth muscle,
narrowing of airways,
increased permeability of blood vessels,
increased mucus production,
mucus plugging,
acute inflammation resulting in edema.
What causes polyphonic wheezing in asthma?
Polyphonic wheezing in asthma is caused by narrowing of bronchi of different calibres.
What is dynamic hyperinflation in asthma?
Dynamic hyperinflation in asthma is the narrowing of bronchi less than 2 cm, leading to closure at low lung volumes, air trapping, increase in residual volume (RV), and increase in total lung capacity (TLC).
What happens with increased severity and chronicity of asthma?
With increased severity and chronicity of asthma, there is remodelling of the airways, collagen deposition, and fibrosis of the airway wall, leading to fixed narrowing.
What type of cells are associated with acute asthma?
Eosinophils are associated with acute asthma.
What type of cells are associated with persistent airway inflammation in asthma?
Neutrophils are associated with persistent airway inflammation in asthma.
What is “steroid-dependant” asthma?
“Steroid-dependant” asthma refers to asthma that is persistent and requires treatment with steroids to control symptoms.
what are examples of environmental triggers for acute asthma
- animal dander, HDM, grass and tree pollen, mould
- viral and bacterial infection
- atmospheric pollution: ozone (O3), SO2, NO, fumes, thunder storms
- perfumes, hair sprays, plug-ins
- cigarette smoking, passive smoking
- indoor fire, chlorine (swimming pool, cleaning products), paints
- cold air/change in temperature
what are some triggers for acute asthma
- Drugs:
- aspirin
- NSAIDS* NSAIDS = non-steroidal anti-inflammatory drugs
- β-blockers
- Physiological:
- pregnancy
- premenstrual
- exercise
- Occupational Asthma
what are the symptoms of asthma during exacerbations
- breathlessness
- Chest tightness
- Wheeze
- Cough
- Between exacerbations:
- Completely well
- Mild chest tightness
- Occasional wheeze
- Dry cough (cough-variant asthma)
What is diurnal variability in asthma?
Diurnal variability in asthma is worse at night and early morning and is linked to the Circadian rhythm.
What are the signs of acute asthma?
During an acute asthma exacerbation, the following may be present:
tachypnea (breathlessness with a raised respiratory rate),
tachycardia,
Polyphonic wheeze during inspiration and expiration,
signs of hyperinflation.
In severe cases,
cyanosis, a silent chest,
and bradycardia may also be present.
What should you expect from a clinical examination of someone with acute asthma?
A clinical examination of someone with acute asthma may be normal in between exacerbations.
What are the blood tests done for suspected asthma?
Full blood count and raised eosinophil count. Raised IgE and radioallergosorbent test (RAST) if a specific allergy is suspected.
What is the purpose of a skin prick test for allergens?
To test for allergens such as tree pollen, grass pollen, dog, cat, horse, feather, HDM, and aspergillus fumigatus.
What is the purpose of a chest X-ray (CXR) in suspected asthma?
To assess the lungs and look for any signs of lung damage or other abnormalities.
What is the purpose of peak flow (PEF) and PEF homework in suspected asthma?
To measure the airflow in the lungs and assess any diurnal variability in the patient’s breathing. A 20% or greater variability between morning and evening values suggests asthma.
What is the purpose of spirometry in suspected asthma?
To measure the amount of air a person can exhale and the speed at which they can exhale.
What is a full lung function test with reversibility to bronchodilator?
A test that measures the lung function before and after inhaling a bronchodilator (e.g. salbutamol) to assess the patient’s ability to reverse bronchoconstriction.
When is a HRCT (High-Resolution Computed Tomography) test done for suspected asthma?
If emphysema or bronchiectasis are suspected.
What is the purpose of a methacholine or histamine provocation test?
To assess the patient’s airways and determine their responsiveness to different stimuli.
When is a HRCT thorax done?
If bronchiectasis is a possibility.
What is the purpose of sputum analysis in suspected asthma?
To determine any underlying infections or inflammation in the lungs through microbiological analysis and differential cell count.
What does Spirometry show in asthma?
Spirometry will show obstruction, with reduced FEV1 and FEV1/FVC < 70%.
What is the significance of bronchodilator reversibility in asthma?
Reversibility to bronchodilator 20 minutes after 200 mcg inhaled salbutamol with the FEV1 increasing by at least 15% of baseline or by more than 200 ml is significant. Patients with COPD will have little or no reversibility.
What are the results of lung function test in asthma?
Lung function test shows an increase in Total Lung Capacity (TLC) and Residual Volume (RV) due to air trapping and normal Transfer Factor/Diffusing Capacity (TLCO/DLCO).
What is Fractional Exhaled Nitric Oxide (FENO)?
FENO is a measure of airways eosinophilic inflammation
What is the significance of a positive FENO test?
A positive FENO test (> 40ppb) supports the diagnosis of asthma.
Where can FENO test be done?
FENO test can be done in GP and hospital clinics.
What is the use of FENO test in monitoring treatment/compliance?
FENO test can be used to monitor treatment and look at compliance.
What can CXR show in mild asthma?
CXR may be normal in mild asthma.
What can CXR show in asthma with increased lung volumes?
CXR may show hyperinflation with increased lung volumes and flat diaphragms, with 6 anterior ribs or 10 posterior ribs in the mid-clavicular line and a vertical and narrow heart.
What does HRCT show in asthma?
HRCT will show air trapping.
What is one important aspect of the management of asthma?
One important aspect of the management of asthma is to avoid allergens if possible.
What are the forms of therapy for asthma management?
The forms of therapy for asthma management are inhaled therapy and oral therapy.
What guidelines are used for the management of asthma?
The British Thoracic Society (BTS) Guidelines are used for the management of asthma.
What is the management of acute exacerbation of asthma?
The management of acute exacerbation of asthma involves following the BTS Guidelines.
What are the aims of pharmacological management of asthma?
To control symptoms, achieve best possible pulmonary function, prevent exacerbations, reduce morbidity and mortality, and minimize side effects