Asthma Flashcards
what is asthma (definition)
recurrent and reversible (in short term) obstruction to the airways in response to substance or stimuli
chronic inflammatory disorder
3 characteristics of asthma
airflow limitation
airway (bronchial hyper-responsiveness)
bronchial inflammation
what is airflow limitation
reversible spontaneously or with treatment
reversible airway obstruction - constriction
how is airflow limitation measured
lung function test
how does bronchial hyper responsiveness contribute to asthma
increased airway sensitivity = twitchy smooth muslce
what is bronchial hyperresponsiveness due to
epithelial damage exposes sensory nerve endings
c-fibres
irritant receptors
what does bronchial hyperresponsivenss lead to
neurogenic inflammation - sensory nerve endings release peptides
what is the most important factor leading to asthma
bronchial hyperresponsiveness
what cells cause bronchial inflammation
T cells + mast cless
EUSINOPHILIA
what causes asthma
allergens (atopic) fungal atmospheric pollutants drugs genetic factors occupational sensitisers cold dry air + exercise emotion resp infections
give an example of an allergen that causes asthma
house dust mites
what happens during in immediate asthma attack in the early reaction
airflow limitation
max 15-20mins
1 hour subsides
why is a prolonged sustained asthma attack after the early reaction more dangerous
doesn’t respond well to inhalation of bronchodilator eg. salbutamol
what reaction occurs after occupational sensitisers inhalation (eg. isocyanates) in asthmatics
isolate late-phase reactions (no preceding immediate response)
BHR increases
what is the hygiene hypothesis
growing up in clean environment predisposes IgE response to allergens
growing up in dirtier environment allows immune response to avoid allergic response
Pathogens stimulate TLRs on immune/epithelial cells to direct an immune inflammatory response away from allergic TH2 towards protective TH1
give an example of a fugal that causes asthma
aspergillus fumigates
INTRINSIC
increases sensitivity
give examples of atmospheric pollutants that cause asthma
SO2
tobacco smoke
perfumes
what drugs can trigger an asthma attack
NSAIDS
B-adrenoceptor antagonists (beta blockers)
how do NSAIDS trigger an asthma attack in affected individuals
aspirin-intolerated asthma
reduced PGE2
causes overproduction of cysteine leukotrienes by eusinophils, mast cells and macrophages
what can partially reverse an asthma attack caused by NSAIDS
anti-leukotrine therapy
list 3 (NSAID) drugs that can induce asthma
asprin
propionic acid derivatives =
indomethacin
ibuprofen
what percentage of asthma does NSAIDS cause
trigger 5%
what type of people is NSAID intolerance common in
people with nasal polyps
how do NSAIDS cause asthma in some people
inhibit arachidonic acid metabolism via cycle-oxigenase (COX) pathway
preventing synthesis of PGs
how do beta-blockers trigger the onset of asthma in some individuals
parasympathetic NS causes bronchoconstricition in ASM
no direct sympathetic innervation of ASM and antagonists
what do asthmatics develop after exercising in cold dry air
exercise wheeze
release of histamine, PGs and LTs from mast cells + stimulation of neural reflexes when epithelial lining of bronchi becomes hyperosmolar due to dry, cold air
what test can be performed after asthmatics exercise in cold dry air
hypertonic (saline/mannitol) provocation test after exercise
give an example of occupational sensitisers that induce asthma in some individuals
isocyanates
acid anhydrides
high molecular weight compounds - flour, dust = IgE antibody reaction
how do occupational sensitisers cause asthma
chemicals bond to epithelial cells activating them and provide haptens recognised by T cells
beta-blockers should/should not be used to treat hypertension or angina in asthmatics
SHOULD NOT
how does adrenaline cause bronchodilation
it is an antagonist of parasympathetic receptors
it acts on B2 receptors on ASM
how do beta-blockers eg. propranolol trigger an asthma attack
they inhibit B2 adrenoceptors preventing andrenaline from binding causing bronchoconstriction
what are the 2 types of beta blocker
B2 adrenoceptor blockers eg. propranolol
selective B1 adrenergic blockers eg. atenolol
what respiratory infections can cause asthma
viral inactions eg. rhinovirus, parainfluenza and RSV
are viral infections an intrinsic or extrinsic cause of asthma
EXTRINSIC
what are the extrinsic causes of asthma
external environmental factors
Allergens - IgE response
Chemicals in workplace
extrinsic causes of asthma are more common in children/adults
CHILDREN
what is intrinsic causes of asthma
no external cause identified adult onset asthma non-atopic aspergillus fumigatus due to extrinsic causes
what does NSAIDS stand for
non-steroidal anti-inflammatory drugs
what extrinsic causes cause intrinsic asthama
sensitisation due to occupational agents (toluene isocyanate)
NSAIDS
b-adrenoceptor blocking agens
what is hay fever an example of
atopic asthma
usually runs in families
what happens during an acute asthma response (4 stages)
- airway narrowing, impeded airflow (reversible)
- airway hyper responsiveness + airway spasms = bronchoconstriction
- increased mucosal inflammation + recruitment of inflammatory cells (eosinophils, mast cells, neutrophils, T lymphocytes)
- hyper secretion of mucus = mucus plugs
what causes chronic asthma
long standing inflammation in bronchioles
what happens as a result of chronic asthma
changes in bronchioles
what happens as a result of long standing bronchial inflammation resulting in increased bronchial constriction
plasma exudation
accumulation of interstitial fluid = oedema
increased smooth muscle mass = hypertrophy + hyperplasia
matrix desposition
sub-epithelial fibrosis
increased mucus = mucus plugging
epithelial damage - sensory nerve endings exposed
how does exposure of sensory nerve endings increase bronchoconstriction
feed forward effect, inhaled allergens have direct access to blood and tissue causing more inflammation
chronic asthma results in decreased/increased FEV1 + PEFR
decreased
why is chronic asthma worse than acute asthma
IRREVERSIBLE airflow limitation due to inflammation
what happens to the airways as a result of chronic asthma
airway remodelling = excess narrowing & swelling outside the smooth muscle layer
what changes in the epithelium causes airway remodelling due to chronic asthma
conducting airway epithelium is stressed/damaged with loss of ciliated columnar cells
metaplasia - increased mucus-secreting goblet cells
lots of mediators
epithelium becomes hyperresponsive = increased sensitivity to bronchoconstrictors, more vulnerable to viruses
how does changes in the epithelium basement membrane cause airway remodelling
increased desposition of repair collagens + proteoglycans in laminal reticlaris beneath basement membrane
increased disposition of lamina, tenascin + fibronectin
increased disposition of matrix proteins
THICKENED BASEMENT MEMBRANE
what does collagen despostitions cause
activation of underlying fibroblast sheath
contractile myofibroblasts
how does changes to airway smooth muscle cause airway remodelling in chronic ashtma
hypertrophy
hyperplasia of helical bands of ASM
bands contract more easily, stay contracted due to change in actin-myosin cross-link cyclin
asthmatic airways contract too much and too easily
how do nerves cause airway remodelling
nerve reflexes cause airway irritability
4 factors that cause a change in the airways in asthmatics
- increased smooth muscle mass
- accumulation of interstitial fluid
- increased mucus secretion
- epithelial damage
in asthma what drives mild/moderate inflammation
Th-2 lymphocytes
what do Th-2 cells facillitate
produce IL-4 = IgE synthesis
produce IL-5 = eosinophilic inflammation
what drives sever/chronic asthma
loss of sensitivity to corticosteroids
Th1 + Th 2 response
what does a Th1 response do
Th1 cells release mediators eg. TNF-a
causes tissue damage, mucus metaplasia, aberrant epithelial + mesenchymal repair
where are mast cells increased in asthma inflammatory response
epithelium
smooth muscle
mucous glands
what mediators to mast cells release in the immediate asthma reation
histamine
tryptase
PGD2
cysteine leukotrines
what do mediators from mast cells act on
ASM
blood vessels
mucous secreting cells
sensory nerves
what do mast cells release in the late asthma response and in chronic asthma
cytokine
chemokines
growth factors
what are mast cells inhibited by
sodium cromoglycate
B2 agonsits
where is there large numbers of eosinophils in asthma
bronchial wall + secretions
what triggers eosinophilic recruitment of the airways
cytokines: IL-3, IL-5, GM-CSF
chemokine: act on type 3 C-C chemokine recepors (CCR-3)
what is the role of mediators
prime eosinophils for enhanced mediator secretions
what do activated eosinophils release
LTC4, MBP, ECP, EPX (all toxic to epithelia cells)
what effect does corticosteroids have on eosinophils
they decrease the number and activation of eosinophils
where is there lots of dendritic cells and lymphocytes in asthma response
in mucous membranes of airways and alveoli
what is the role of dendritic cells + lymphocytes in an asthma reaction
uptake of allergens
CD4+ cells show evidence of activation
what cytokines released by dendritic cells + lymphocytes cause migration and activation of mast cells
IL-3, IL-4, IL-9, IL-13
what cytokines released by dendritic cells + lymphocytes cause migration and activation of eosinophils
IL-3, Il-5, GM-CSF
what cytokine maintain pro allergic TH2
IL-3, IL-4
describe the helper T cell response during an immune response in atopic and nonatopic individuals
atopic: strong TH2 response
non-atopic: low-level TH1 response
what type of inflammatory response occurs in atopic and non-atopic
atopic: antibody mediated
non-atopic: cell-mediated
what antibodies and inflammatory cells are involved in atopic and non-atopic responses
atopic: IgE
non-atopic: IgG + macrophages
individuals who readily produce IgE to common antigens are more/less prone to allergic asthma
MORE
what type of reaction is an allergic asthma reaction
TYPE 1 Hypersensitivity reaction
caused by antigen/IgE induced mast cell degranulation
what do mast cells release in an allergic asthma reaction
spasmogens
histamine
leukotrienes (LTC4 + LTD+4)
chemotaxis + chemokine (prostaglandins D2 + platelet activating factors)
what do spasmogens + histamine + leukotrienes cause
increased mucus product. and therefore bronchoconstriction
what happens during the late asthma response
chmokines + chemotaxis infiltrate mast cells + Th2 lymphocytes
stimulating resale of cytokines which attracts eosinophils and neutrophils to area
causing: epithelial damage, airway limitation, hyper-reactivity, bronchospasm, wheeze, cough
what happens if inflammation in late reaction isn’t treated
collagen lays down
fibrosis
formation of scar tissue
DOES NOT RESPOND TO BRONCHODILATORS
what treatment should be given if there is no bronchodilator response due to fibrosis and collagen deposition
CORTICOSTEROIDS
in an early asthma attack what occurs during the early (immediate phase)
alveolar hyperventilation increased resp drive decreased PaO2 decreased PaCO2 Bronchoconstriction normally subsides in 2 hours
in the late phase asthma attack what occurs
alveolar hypoventilation decreased resp drive decreased PaO2 Increased PaCO2 hypercapnic drive = high conc of O2 (60%) mechanical venitaltion
what is asthmaticus
acute severe asthma = medical emergency
who gets asthma
5-10% industrialised countries childhood (3-5) more common in UK, Australia, NZ less common in Far East + africa Genetics + Environment
what symptoms do asthmatics present with
episodic: intermittent attacks of bronchoconstriction
- tight chest
- wheezing (increased resistance + turbulence)
- creating difficulty (worse night + morning)
cough (worse at night)
what other symptom are children with atopic asthma likely to have
eczema (dermatitis)
what clinical signs do people which asthma present with
increased IgE: rhinitis, conjunctivitis, eczema
blood eosinophilia > 4%
steroid/b-agonist responsive
family history
what genes can predispose people to asthma
genes controlling cytokine production (IL-)
affects mast cells + eosinophil development
genes encode neuropeptide S receptor
what gene defect predisposed people to atopic asthma
polymorphic variation in proteins in Il-4/IL-13 pathway
what gene defect can affect airway hyper-responsiveness and tissue remodelling
ADAM 33 (diintegin + metalloproteinase) on chromosome 20p13
what are the 4 hallmarks during examination of someone with asthma
WHEEZE
tight chest
breathlessness
cough
what do we look for in the blood/sputum of asthmatics
high eosinophils (more significant in sputum) asthmatics don't usually produce sputum
what lung function tests can be used to assess asthma
PEFR (peak expiratory flow rate)
spirometry = reduced forced expiratory ratio
how is peak flow (PEFR) measured
measured on walking prior to taking bronchodilator + before bed after bronchodilator
diurnal variation of peak flow to see if asthma symptoms at night
keep diary
what does spirometry asssess
reversibility
how does spirometry diagnose asthma
demonstrating > 15% improvement in FEV1 or PEFR after inhalation of bronchodilator
FVC = normal
FEV1 = decreased
what FEV1/FEV ratio indicates asthma (obstructive airway disease)
< 75%
how does spirometry assess asthma severity
as the conc of bronchoconstrictor increases the % fall in FEV1 increased
> severity = > FEV1 fall
what is FEV1
forced expiratory volume (in litres) in 1 second
mild asthma shows hypersensitivity/hyper-reactivity and a moderate/large fall in FEV1
hypersensitivity
moderate
severe asthma shows hypersensitivity/hyper-reactivity and a moderate/large fall in FEV1
hyper-reactivity
large
how does expiration differ in asthmatics to healthy people
asthmatics have slower gas flow, harder to breath out, exhalation declines
how can exercise be used to test asthma in children
child - 6 min treadmill run
HR > 160 bpm
what is bronchial provocation testing
inhaled bronchonstictors eg. spasmogens cause bronchospasm
give examples of bronchoconstrictors
mannitol
histamine - activates ASM H1 receptor
methalcholine - activates ASM M3 receptor
what people will react only to higher dose of methalcholine in bronchial provocation tests
extreme exertion - winter sports enthusiast
wheeze/lots of coughing after viral infection
seasonal wheeze in pollen season
allergic rhinitis
what do some x-rays of asthmatic patients show
over-inflation
x-ray can exclude pneumothorax as similar symptoms
if a patient has suspected asthma due to severe airflow limitation what can be used to see if they are asthmatic
trail of corticosteroids
prednisolone 30 mg orally for 2 weeks
lung function measured before and after
FEV improvement > 15%
how are bronchial provocation tests carried out
ask patient to inhale gradually increasing conc of histamine or methalcholine
induces transient airflow limitation
OR
inhalation of cold dry air, mannitol/hypertonic saline causes release of endogenous mediators eg. histamine, prostaglandins
asthmatics respond to very low/high does of methalcholine
Low PD20FEV1
how do bronchial provocation tests assess asthma severity
severity of BHR graded according to provocation dose of conc of agonise that produces a 20% fall in FEV1 (PD20 FEV1)
how does inhaled NO indicate asthma
measures airway limitation + index corticosteroid response
If high NO is exhaled what does this suggest
asthma
how does a skin prick test test for asthma
identifies allergic/extrinsic asthma
if SPT is not available how can allergen-specific IgE be measured
in serum
patient must be taking antihistamines
what are the adverse effects of SABAs
fine tremor tachycardia cardiac dysrhythmia hypokalaemia increased BP palpitations
how do short-acting B2 adrenoceptors agonists (SABAs) treat asthma
stimulate bronchial smooth muscle B2 receptors - increased cAMP
relax bronchial smooth muscle 3-5 hours
mucus clearance
decrease mast cell/monocyte mediatory release
examples of SABAs
salbutamol
albuterol
terbutaline
what is the first line treatment for mild and intermittent asthma
SABAs
when are SABAs taken
when needed
what route are SABAs taken by
inhalation - metered dose. dry powder (lessens systemic effect)
IV in emergency
how do SABAs act
rapidly - 5 mins
max effect 30 mins
what are LABAs
long acting B2 adrenoceptor agonists
give examples of LABAs
salmeterol
formoterol
why are LABAs used over SABAs sometimes
NOCTURNAL use
8 hours
long half life
why are SABAs used over LABAs sometimes
LABAs are NOT for acute bronchospasm relief
salmeterol over formoterol = slow to act
are LABAs used as monotherapy, what are they co-administered with
NO
add on asthma therapy
ALWAYS co-adminsitered with glucorticoids
what are the adverse affects of LABAs
can increase asthmatic deaths
use of non-selective B-adrenoceptor antagonist eg. propranolol in asthmatics = contrainicated - bronchospasm
what is the advantage of using selective B2 adrenoceptor agonists
they reduce harmful stimulation of cardiac B1 adrenoceptors
non-selective agonists eg isoprenaline = redundant
what do combination inhalers consist of
ICS (glucocorteroid) + LABA
eg. Beclometasone, Formorterol
why are combination inhalers safe
high therapeutic ratio
B2 down regulation + tachyphylaxis with chronic LABA
how do CysLT1 receptor antagonists (leukotrienes) treat asthma
anti-inflammatory
act competitively at CysLT1 receptor, blocking the receptor
derived from mast cells
infiltrate inflammatory cells causing: smooth muscle contraction, mucus secretion + oedema
Give examples of CysLT1s
LTC4
LTD4
LTE4
when are cysLT1s used
second line therapy
what is a 2nd line complimentary non-steroidal anti-inflammatory that is add on to inhaled steroid against bronchospasm in mild and persistent asthma
CysLT1 receptor antagonists (leukotrienes)
when is CysLT1 receptor antagonists combined inhaled with corticosteroids
in severe asthma
what is montelukask
taken orally, once daily, high therapeutic ration drug that is a non-steroidal anti-inflammatory that can be added to a corticosteroid
adverse effects of montelukask
headache
gastrointestinal upset
what is montelukask (a CysLT) effective against
antigen-induced + exercise induced bronchospasm
allergic rhinitis + anti-histamine
what do cysLTs eg montelukask NOT treat
relief of acute severe asthma
what are methylxanthines
bronchodilators + anti-inflammatory
increase diaphragmatic contractibility, improves ventilation and reduces fatigue
added to inhaled steroid as complimentary non steroidal anti-inflammatory
inhibit mediator release from mast cells
increase mucus clearing
give an example of methylxanthines
theophylline
aminophylline
what drug that can be used to treat asthma is present in
coffees, tea, chocolate beverages
when is theophylline used to treat asthma
oral maintanence
what does theophylline activate
histone deacetylase HDAC
anti-inflammatory action of glucocorticoids
add on therapy
why must theophylline be monitored
due to drug interactions CYP450 drug interactions eg. antibitiotics inhibit erythromycin
what drug is given as an add on during an acute asthma attack via IV
aminophylline
what is the disadvantages of methylxanthine
low therapeutic ratio - drug interactions narrow therapeutic window dysrhythmia seizures hypotension nausea vomiting abdominal discomfort headache MUST GIVE ACCURATE DOSAGE
advantage of using methylxanthines
oral route = sustained effect
what type of drugs are methylxanthines
second line combined with B2 adrenoceptor agonists and glucocorticoids
what is the action of methylxanthines
inhibitor of phosphodiserases isoforms (PDE3 + 4) that activates cAMP and cGMP (second messengers Thant relax smooth muscle
what is ibruprofen
anti-inflammatory that can trigger bronchospasm in sensitive individuals
what is a first line preventer inhaler that is an anti-inflammatory agent (surpasses inflammation)
QVAR
what synthesises corticosteroids on demand
adrenal cortex
released from zona fasciculata
why are corticosteroids given to a patient
reduce exacerbations in eosinophilic COPD (ACOS- asthma COPD overlap syndrome)
optimises lung delivery (extra fine solution HFA/Spacer)
what is the most important glucocorticoid
cortisol (hydrocortisone)
what is the first line treatment for asthma where there is inflammation
glucocorticoids = CORTISOL
what effect does cortisol have in the body
decreases inflammation, immunological response, glucose utilisation
increases liver deposition, gluconeogenesis, liver glucose output, protein catabolism, bone catabolism, gastric acid + peptide secretions
do glucocorticoids have direct bronchodilator action
NO
does cortisol relive bronchospasms
NO
why is cortisol inhaled
to minimise adverse effects
describe the 4 stages of the mechanism of action of cortisol
- lipophilic (enter by diffusion)
- combine with GRa causing dissociation of inhibitory heart shock proteins (HPS90) the activated receptor translocates to the nucleus by importins
- in nucleus receptor monomers become homodimers which bind to GRE (glucocorticoid response elements ) in the promotor region of specific genes
- transcription of specific genes: switched on (transactivated)/switched off (trans repressed) to alter mRNA levels and mediate protein synthesis
in inflammation of bronchial asthma what are genes regulated by
glucocorticoid response elements
modifying chromatin structure (deacetylation of histones)
what effect does cortisol have on genes
increases gene transcription encoding anti-inflammatory proteins
decreases gene transcription for genes encoding inflammatory proteins
how does cortisol prevent inflammatory gene expression
acetylation of histones by HATs (histone acetyltransferase)
acetylation unwinds DNA from histones causing transcription
glucocorticoids recruit deacetylase HDAC activating genes and switches off gene transcription
how does cortisol switching off gene transcription of inflammatory proteins stop the inflammatory response
decreased Th2 cytokines (IL-4, IL-5) Th2 apoptosis eosinophils don't enter lungs eosinophils apoptosis mast cells reduced decrease Fc receptors on mast cells prevent IgE production restoration
what effect does glucocorticoid have on eosinophils
decrease number by apoptosis
what effect does glucocorticoid have on T cells
decrease cytokines
what effect does glucocorticoid have on mast cells
decrease numbers
what effect does glucocorticoid have on macrophages
decrease their release of cytokines
what effect does glucocorticoid have on dendritic cells
decrease number
what effect does glucocorticoid have on epithelial cells
decrease cytokine mediators
what effect does glucocorticoid have on endothelial cells
decrease leakiness
what effect does glucocorticoid have on ASM
increased B2 adrenoceptors
decrease cytokines
what effect does glucocorticoid have on mucus glands
decrease mucus secretions
why are glucocorticoids used
prevent inflammation and resolves established inflammation
do glucocorticoids have a short or long term effect and what is this effect
long term effect against allergens
what should glucocorticoids be combined with
LABAs
adverse effects of cortisol
dysphonia (weak/horse voice) oropharyngeal candidiasis (thrush)
3 examples of glucocorticoid + LABA used to treat mild asthma
becolmetasone
budesonide
fluticasone
how longs does becolmetasone have effect for
efficacy develops over days
why is becolmetasone inhaled by metered dose
to minimise unwanted systemic effects
what steroid is administered by IV
Hydrocortisone
what is an oral steroid with a low therapeutic ratio that is administered for acute exacerbations NOT maintenace
Prednisolone
side effects of prednisolone
retarded growth
water retention
hypertension
weight gain
what is an inhaled steroid that has a high therapeutic ration and is used to treat chronic asthma, its maintenance can be given as mono therapy
becolmethasone
where are mineralocorticoids released from in the adrenals
zona gomerulosa
give an example fo a mineralocorticoid and its function
aldosterone
regulates salt and water retention by kidneys
what should be given to patients with poor inhaler technique
SPACER
avoids coordination problems with pMDI (metered dose)
improves lung deposition
what does a spacer device reduce
oropharyngeal + laryngeal side effects
systemic absorption from swallowed fraction
particle size + velocity
what people usually require a spacer
children
what anti-inflammatory preventer is a second line drug that is a mast cell stabiliser therefore surpasses histamine release from mast cells
Cromones
what method are croons administered by
inhaled only
why are croons infrequently used
poor efficacy
weak effect
how do cromones prevent inflammation
decreases sensitivity of sensory c-fibres that trigger exaggerated reflex
reduces cytokines
give an example of a cromone
sodium cromoglicate
- inhaled (little systemic absorption)
why is sodium cromoglicate given
reduces asthma attack in early + late phase
it takes several weeks to block late phase using frequent dosing
why is sodium cromoglicate not completely useful against asthma attack
it takes several weeks to block late phase using frequent dosing
what patients are commonly given sodium cromoglicate
children
what anti-IgE drug is given to people with severe persisting allergic asthma to reduce exacerbations and is given via IV every 2-4 weeks
Omalizumab
what is the action of omalzumab
inhibits binding to high-affinity IgE receptor (prevents Fce attachment) so inhibits Th2 response and suppresses mediators from mast cells/basophil release
also reduces Fee receptor expression on inflammatory cells
what drug is a monoclonal anti-IL5 antibody used to treat severe refectory eosinophilia ( >300 ul eosinophils) and reduce exacerbations
mepolizumab
reslizumab
how does mepolizumab work
blocks effect of TH2 cytokine IL-5 release (reducing eosinophilic inflammation)
what is the treatment of chronic asthma
- inhaled steroid suppresses inflammatory cascade
- anti-IL-5 (mepolizumab)
- inhaled becolmethasone
- LABA/LAMA to stabilise ASM
- (+/-) non steroid anti-inflammatory eg. theophylline, anti-leyukotrine, cromoglicate
if an asthma is atopic what should be prescribed
anti-IgE eg Omalizub
what is the treatment given to acute asthma
- oral prednisolone (or IV hydrocortisone) if rapidly deteriorating
- nebulised high dose salbutamol (+/- nebulised ipratoropium) (+/- aminophylline/magnesium)
- at least 60% oxygen
- if falling PaO2 and rising PAO2 ITU assisted mechanical intubated ventilation
in asthma hat alliterates decline in lung function
airway remodelling
what is the stepwise therapy of asthma
- inhaled SABA (blue inhaler)
- addition of inhaled low dose steroid (brown inhaler)
- addition of LABA + increased dose of inhaled steroid
- increased dose of inhaled steroid + leukotrienes receptor antagonists (MONTELUKAST = for atopic asthma)
- ADD low dose oral steroid eg. ozmilzub + refer to specialist
what is a QVAR inhaler
ICS + LABA + LAMA
a patient presents to you with inability to complete sentences in 1 breath, resp rate >25, tachycardia > 110 bpm + pulse paradox and a PEFR < 50% predicted normal/best what is wrong with them
Acute severe asthma
list the features of an acute severe asthma attack
silent chest, cyanosis, feeble resp effort
exhaustion, confusion, coma
bradycardia or hypotension
PEFR < 30%
High PaCO2 > 6 kPa
severe hyperaemia PaO2 < 8 kPa with O2 treatment
low arterial pH
what treatment should be given to a patient with severe asthma attack
- nebulised SA bronchodilators
- nebulised antimuscarinics = IPRATROPIUM BROMIDE
- IV hydrocortisone
- SABA/magnesium sulphate (IV)
- oral prednisolone
- ventilation
what happens to FEV1 during an asthma attack in the immediate phase then in the late phase
sudden fall then begins to increase then a large slower fall in FEV1 and a longer increase back to normal
in an asthma attack what type of reaction occurs in the early phase
Type I hypersensitivity reactio
in asthma attack what type of reaction occurs in the late phase
Type IV hypersensitivity reaction, delayed inflammation
in early phase of an asthma attack what causes bronchospasm
spasmogens
CysLTs
Histamine
RELEASED FROM MAST CELLS
in early phase of an asthma attack what causes the late phase and exacerbates the immune response
chemotaxis and chemokines
FROM MAST CELLS
what happens during the late phase of an asthma attack
infiltration of cytokines releasing Th2 cells + monocytes
activation of inflammatory cells - eosinophils
what does CysLTs cause in an acute asthma attack
airway hyper-responsiveness + airway inflammation bronchospasm wheeze mucus over-production cough
what does an infiltration of eosinophils cause in an asthma attack
epithelial damage airway hyper-responsiveness bronchospasm wheeze mucus over-production cough