what is asthma?
- Inflammatory disease of the airway○ Recurrent reversible airway obstruction - in response to irritant stimuli
○ Hypersecretion- mucus by bronchial epithelial cells
○ Eosinophil ( disease fighting white blood cells) infiltration
Bronchial smooth muscles cells hyperplasia causing airway hyper- responsive (increased sensitivity of airways to chemicals, cold airway- abnormal) and bronchospasm ( abnormal contraction causing obstruction in airway)
what is the differences between healthy airway, asthma, asthma attack?
Smooth muscles increase - lumen becomes smaller - constricted airway
What is the pathogenesis of asthma ( what is causing asthma)?
Exact causes are unclear but could be genetic, environmental or combination factors
What factors increases the chance to develop the condition?
- born prematurely
- born with bronchochiltis
- exposure to tabacco smoke
- job
- family/genetics
what triggers asthma
- pollen
- excerise
- stress
- mould
- food
- cold environment
- salicylic acid
how is asthma diagnosed? - symptoms
- breathlessness/SOB
- chest tightness
- wheezing
- coughing - occasionally
- daily or seasonal variations
What are the tests which needs to be done (objective test)
- lung function test
- airway inflammation measurement
- airway hypersensitivity measurement
what is airway inflammation measurement
- Measure Fractional exhaled nitric oxide in the breath (FeNO)
When you have asthma there is an increase in intake of nitric oxide synthesis due to imflammation
what is lung function test
- Obstructive spirometry-
Measure lung volumes and capacity to determine the presence of an obstructive or a restrictive diseases. FEV1 and FVC changes will differ depending on the type of diseases
less than 70% = obstructive airway disease
What is bronchodilator reversibility test?
• Determine the presence of a reversible airways obstruction
• Offer In adults (aged 17 and over): Spirometry after inhaling short acting b2AR agonist.
Consider a BDR test in children and young people (aged 5 to 16) with obstructive spirometry
Positive result Improvement in FEV1 of 12% or more
peak flow variability
• Determine the presence of daily variability of air peak flow.
- Monitor the peak flow for variability for 2-4 weeks.
- exceeds 20% (and is at least 60 l/min) the diagnosis of asthma is strongly supported.
what is direct bronchial test?
-hyperresponsiveness/ hypersensitivity test
· Asthmatics usually demonstrate an excessive response to an inhaled dose of methacholine or histamine which causes little or no change in lung function in normal healthy individuals.
Graph shows Dose-response curves to inhaled methacholine in a healthy, mild-asthmatic, and severe-asthmatic subject, showing both the leftward shift of the curve (hypersensitivity) and steeper slope (hyperreactivity) that characterise BHR.
what is an immediate phase of an asthma attack
- TRIGGER
- mast cell spasmogen
causes bronchospasm
what is delayed phase of an asthma attack
- chemotaxins
- activate inflammatory cells - monocytes, eosinophils which release leukotrienes, cytokines, eosinophil proteins
- this causes bronchospasm - coughing and wheezing
- increase in hypersensitivity and inflammation
- causes mucus
primary preventions of asthma?
- Multifaceted approach to avoid indoor asthma
- Aeroallergen and food avoidance
- Weight-loss interventions for overweight and obese adults and children with asthma
- Microbial exposure and ‘hygiene hypothesis’
Avoid Smoking and air pollution
secondary preventions of asthma
- cleaning - dust
- ventilation
- breathing execerise program
- family therapy with pharmacotherapy
is bronchodilator a reliever or preventer
reliver
what is the function of a bronchodilator
- SABA
only LABA in MART - fast control less than 7 mins
-relieve asthmatic symptoms for asthmatic patients with infrequent, short-lived wheezed and normal function
what is the preventer/controller and what it is its function?
long acting bronchodilators and anti- inflammatory drugs
LABA (in combination with ICS)
- inhaled and systemic corticosteroid
- leukotriene receptor antagonists ( Inflammatory receptor antagonist)
- long acting muscaranic receptor antagonist
- theophylline
- Why activate b2 adrenoreceptor agonist in the airway smooth muscle
Cause airway smooth muscle relaxation by cAMP-dependent (and independent) mechanisms.
What happens when you give salbutamol/non adrenaline- smooth muscle relaxation?
- Salbutamol given
- Receptor g alpha s protein
- Activation of adenyl cyclase
- Production of cAMP
- Activation of pKA
Causes smooth muscle
Is salbutamol hydrophilic or hydrophobic and use ?
hydrophilic- enter binding site b2ar - reliever - acute asthma
Give examples of long lasting b2 adrenoreceptors agonists
fometerol - lipophilic
salmeterol - lipophilic
How does salbutamol, formoterol and salmeterol act and bind to the b2 adrenergic agonist?
fometrol - fast onset, long duration
sulbutamol - fast onset and short suration
salmeterol - slow onset and long duration
