7.1 Airway Control Flashcards
Asthma can be defined as more than one of what 4 symptoms?
- wheeze
- breathlessness
- chest tightness
- cough
Give the 4 characteristic features of Asthma
- Variable airflow obstruction
- Airway hyper-responsiveness
- Airway inflammation
- Airway remodelling
The inflammatory response in Asthma is driven by what type of cell?
What are the 3 effects this has on the airways?
Th2 cells which leads to:
- mucosal oedema
- bronchoconstriction
- mucus plugging
Smooth muscle dysfunction in asthma leads to what 2 things?
1) increased contraction
2) increased cytokines and chemokines
Give 5 features of ‘airway remodeling’ seen in Asthma
1) Mucus gland hyperplasia (+goblet cells)
2) Subepithelial fibrosis
3) Epithelium desquamation (epithelial damage)
4) Airway wall thickening and SM thickening
5) Increased BM thickness
Give 4 types of immune cells that are raised in Asthma
1) Th2 cells (CD4+)
2) Mast cells
3) Eosinophils
4) Neutrophils
Asthma is considered a heterogeneous disease, what does this mean?
There are many patterns of Asthma which vary in their:
- Pathology- eosinophil vs neutrophil inflammation
- Symptom patterns + triggers of exacerbations
- Response to treatment
What is meant by the ‘stepwise management of asthma’ in adults
A prinicipal applied to prevent ‘over-treatment’
It is very easy to start patients on medications but very difficult to step them down
Give 5 aims of asthma control
1) minimal symptoms during day and night
2) minimal need for reliever medication
3) no exacerbations
4) no limitation of physical activity
5) normal lung function (FEV1 and/or PEF >80% predicted or best)
Before initiating a new drug therapy for Asthma, what 3 things must we consider
1) check compliance with existing therapies
2) check inhaler technique
3) eliminate trigger factors
What catagory of Asthma begins at step 1 on the treatment ladder
Mild intermittent asthma
What treatment is used in Step 1 treatment + 2 examples
Are these ‘relievers’ or ‘preventers’?
Inhaled short-acting β2-agonists
- eg salbutamol, terbutaline
Function to reverse and prevent bronchoconstriction i.e. on exercise and are therefore ‘relievers’
What is the main target of short acting β2-agonists
Main target is airway smooth muscle
+ potentially inhibits mast cell degranulation (with intermittent use ONLY)
How does effect on mast cells differ in intermitent vs regular use of β2-agonists
What must we therefore advise patients?
Intermittently ➞ inhibits mast cell degranulation
Regular use ➞ increased mast cell degranulation in response to allergens
MUST advise patients to use ONLY as-required as regular use will reduce asthma control
Does increasing dose of β2-agonists provide more airway relaxation? Why?
No because saturation of β2-agonist pathway occurs very easily. There is not enough substrate to cope with an increased lode of drug
Give the MoA of β2-agonists on airway SM
Give the 4 classes of β2-agonists and include:
- Speed of onset
- Duration of action
- 1-2 examples for each
Formoterol has a ______ onset of action similar to ______
rapid, salbutamol
Give 4 β2-agonist side effects
- Tachycardia
- Palpitations
- Tremor
- Anxiety
(+ many other adrenergic effects)
What is Step 2 in Asthma treatment?
Are these ‘relievers’ or ‘preventers’?
Regular preventer therapy through use of Inhaled corticosteroids
What 4 criteria are required to transition from step 1 to step 2 treatment in Asthma?
1) using β2-agonist ≥3 times/week
2) Symptoms ≥3 times/week
3) Waking up in the morning wheezy ≥1 time/week
4) Exacerbation requiring oral steroids in last 2 years
What is the main target of corticosteroids?
Inflammation
Give 4 positive effects of corticosteroids
1) Improve symptoms
2) Improve lung function
3) Reduce exacerbations
4) Prevent death
Give the MoA of corticosteroids
CS bind glucocorticoid receptor causing downregulation of inflammation through:
1) transactivation ➞ regulates Annexin 1 which inhibits leukocyte inflammation events
2) transrepression ➞ upregulates the inhibtor of NF-κB
What is the chemical basis for potency and topical selectivity of inhaled GCS
The lipophilic substituents on D-ring. This determines how long the molecule remains in the intended target organ
Highly lipophilic ➞ long acting
Less lipophilic ➞ short acting
Lipophilic substituents on GCS lead to what 3 key properties?
1) very high affinity for the GCS receptor
2) increased uptake and dwell time in tissue on local application
3) rapid inactivation by hepatic biotransformation following systemic absorption
When corticosteroids are inhaled what are the 2 routes absorption occur via