asthma -greame Flashcards
what is asthma?
Chronic inflammatory disease affecting airways of the lung
what are the symptoms of asthma?
Variable and recurring symptoms, reversible airflow obstruction, and easily triggered bronchospasms
what causes asthma?
Caused by combination of genetic and environmental factors
what was the old classification of asthma?
Intrinsic Asthma •Caused by factors within the body •‘Non-allergic’ asthma •Skin-prick negative, triggered by cold, exercise, etc •Adult onset Extrinsic Asthma •Caused by inhaling foreign substances •‘Allergic’ asthma •Skin-prick test positive to known allergens e.g. dust mite, pollen, etc •Childhood onset
what are the asthma associated conditions?
COPD/ GERD/ Physiological conditions /other atopic or allergic disorders
what do COPD and asthma have in common?
overlap of symptoms
Both feature immunologically driven lung pathology
what is GERD?
Digestive disorder that affects the sphincter of the lower oesophagus which does not close completely, allowing some semi-digested food and gastric acid to be pushed back up into the oesophagus.
what are the consequences of GERD?
Heart burn and cough
what are the two putative mechanisms in GERD?
- GERD-associate stomach contents may enter lung leading to irritation, tissue damage and progression to asthma
- Asthma-associated pressure changes in the thoracic cavity may inhibit sphincter closing and lead to GERD
why is a physiological dysfunction associated with asthma?
Bi-directional reciprocal incidence in longitudinal studies (those with asthma more like to develop psychological dysfunction but also vice-versa)
what other allergic disorders do people with asthma tend to have?
just under half of asthma patients have allergic rhinitus / ezcema
what are the common triggers of asthma?
Dust mites •Pollen •Cockroach urine •Animal dander •Mould
do paracetamol/ acetaminophen trigger asthma?
no- it was thought that was was being treated was what showed typical asthma symptoms
what happens in sensitisation?
- Antigen can penetrate epithelial layer= dendritic cell maturation
- Resting are ighly phagocytotic can capture through epithelium
- Dendritic cells will mature in response- and process these antigens
- These antigens will be presented on mhc cell to naieve t cells in local lymph nodes
- Recognize and active t cells on these lymph nodes
- Clonal expansion producing daughter of cells
- In an atopic individual may skewe towards a th2/ t helper 2 response
- They can then interact B cells to drive production of IGE
- These b cells will diffeernciate into
- They can bind to mast cells to FC receptor
what are the two respiratory system zones?
conducting zone (nose to the bronchioles) •respiratory zone (from the alveolar duct to the alveoli where gas exchange takes place)
how does the lung changes in response to mediators?
Asthma is primarily involved in the bronchial tree
•Contain smooth muscle and elastic fibres
•Changes based on contraction and relaxation of smooth muscle due to •inflammatory mediators
•Bronchoconstrictors
•bronchodilators
what is the airwaves hyperresponsiveness?
Excessive contractile response of airway smooth muscle in asthma
what does little provocation in an asthmatic induce?
inordinate bronchoconstriction
•airflow obstruction
how does it cause bronchoconstriction and airflow obstruction?
Vagal tone (inadequate relaxation)
•Extracellular calcium
•Smooth muscle mass
•Histamine secretion
what is lung compliace?
is the willingness for the lungs to distend, while elastance is the ability of the lungs to return to their resting position
what is the difference between a normal and a healthy blood vessel?
In healthy individual we have alarge lumen- thin wall of bronchile- thin layer of epithelia cells. Mucous and smooth muscle
Obstructed airway- smooth muscle thicker, inc mucous production and significant decrease in the lumen diameter- significant impact with a smaller lumen to transport gases
what is the clinical adage associated with asthma?
‘all that is asthma does not wheeze and all that wheezes is not asthma’
what is the typcial presentation of asthma?
- Child or adult with a range of spontaneous respiratory symptoms
- Including recurrent cough and nocturnal awakening
- Symptoms triggered by external stimuli, such as allergens, viral infections, exercise and cold air.
what is the new improved asthma diagnosis?
look for - Extra dimensions of airway inflammation
what is Fractional Exhaled Nitric Oxide (FeNO) and what does it measure?
Provides a measure of eosinophilic inflammation of the lungs
•≥35 ppb as a positive test in children
•≥40 ppb as a positive test in adults.
what is a positive test for spirometry ?
FEV1/FVC ratio of less than 70% indicative of obstructive airway disease
what is a positive test in the peak expiratory flow rate?
variation of more than 20%
what are the challenge tests?
lung reactivity:
•Challenge test of airway reactivity
•Increasing dose of •Methacholin•Histamine•mannitol
•Lung function measured by spirometry•20% change diagnostically significant
other tests- blood tests and ski n prick tests
what are bronchodilators used for?
Used for symptom relief in asthma but have no effect on the underlying inflammatory process
how do Inhaled beta2-adrenergic agonists work? symptom relief
Relax smooth muscle by increasing the concentration of cyclic AMP and by opening potassium channels
what is emergency bronchodilators you would give?
adrenaline/epinephrine
what are Corticosteroids used for?
powerful pylotrophic inflamatory drugs
High doses of oral corticosteroids would control almost every asthmatic patient
•Serious systemic side effects limit the dose that can be given over long periods
what is an Anti-IgE Antibody and how does it work?
Omalizumab- it is an ANTI IGE anti-tbody- bind to immunoglobin e in the circulation
- Have their IGE bound- no longer free to bind to receptors on mast cells
- No longer sensitized- decrease in the release of sol mediationrs
what is hyposensitisation?
restore tolerance to these allergens-administer allergen in a diff way than inhaled- fed into them under a rapidly escalating dose controlled
