Transcript Bronchial asthma

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 Asthma
is characterised by chronic airway
inflammation and increased airway hyperresponsiveness leading to symptoms of wheeze,
cough, chest tightness and dyspnoea.
 It is characterised functionally by the presence of
airflow obstruction which is variable over short
periods of time, or is reversible with treatment.
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 The
prevalence of asthma increased steadily over the
latter part of the last century in countries with a Western
lifestyle and is also increasing in developing countries.
 Current estimates suggest that 300 million people worldwide suffer from asthma and an additional 100 million
may be diagnosed with asthma by 2025.
 In childhood, asthma is more common in boys, but
following puberty females are more frequently affected.
 The socio-economic impact of asthma is enormous,
particularly when poor control leads to days lost from
school or work, hospital admissions and, for some
patients, a premature death.
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Dietary
intake may be important. Milk fat and antioxidants
such as vitamin E and selenium may protect against the
development of asthma in children; however, in other
studies early exposure to cows' milk protein has been
linked to the development of atopy and asthma.
 higher levels of Lactobacillus in the gut may protect
against the development of atopic disease.
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 The
increase in asthma may also be linked to the
rise of obesity in Western society through
mechanical mechanisms such as gastrooesophageal reflux.
 Shared genetic traits
 modification of the immune system by diet, or
alteration of airway responsiveness by hormones
are, however, alternative explanations.
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 In
some circumstances the appearance of asthma relates
to the use of medications.
 Beta-adrenoceptor antagonists (β-blockers-even when
administered topically as eye drops) may induce
bronchospasm.
 Aspirin and other non-steroidal anti-inflammatory drugs
are associated with asthma in about 10% of patients.
This is believed to reflect a shift in the metabolism of arachidonic
acid from the cyclo-oxygenase pathway generating prostaglandins,
towards the lipo-oxygenase pathway generating cysteinyl
leukotrienes.
Aspirin-sensitive asthma is often associated with rhinosinusitis and
nasal polyps
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extrinsic
Intrinsic(cryptogenic)
External factor identifiable
No such factor
Serum shows high levels of IgE &IgG
No raised Ab levels but increased
eosinophils present ,aspirin sensitivity, &
presence of nasal polyp
Atopic manifestations may be
present
No atopy
Dermatological and respiratory s/s show Not associated with skin s/s
a see-saw relationship
Positive family history present
Affects persons of 10-15 yrs
Affects persons over 40 yrs
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Causes
 House dust
 Pollen
 Fungi
 Animal hairs
 Insect scales
 Fumes and drugs
 food
 Infection with respiratory syncitial virus
 Exercise induced asthma
 Exposure to cold
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 Once
sensitization occurs these antigens release
chemical mediators from the mast cells by
interacting with the IgE molecules on their surfaceType 1 hypersensitivity reaction-immediate
asthmatic paroxysm
 Some times type 3 hypersensitivity reaction also
occurs and it is mediated by IgG –delayed
paroxysm
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 The
inhalation of an allergen in a sensitised atopic
asthmatic patient results in a two-phase
bronchoconstrictor response .
 The inhaled allergen rapidly interacts with mucosal
mast cells via an IgE-dependent mechanism, resulting
in the release of mediators such as histamine and the
cysteinyl leukotrienes with resulting
bronchoconstriction.
 In persistent asthma a chronic and complex
inflammatory response ensues, which is characterised
by an influx of numerous inflammatory cells, the
transformation and participation of airway structural
cells, and the secretion of an array of cytokines,
chemokines and growth factors
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 Airflow
limitation Usually reverses spontaneously or
with treatment
 Airway hyper-reactivity Exaggerated
bronchoconstriction to a wide range of non-specific
stimuli, e.g. exercise, cold air
 Airway inflammation :Eosinophils, lymphocytes,
mast cells, neutrophils; associated oedema, smooth
muscle hypertrophy and hyperplasia, thickening of
basement membrane, mucous plugging and epithelial
damage
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 With
increasing severity and chronicity of the
disease, remodelling of the airway occurs, leading
to fibrosis of the airway wall, fixed narrowing of the
airway and a reduced response to bronchodilator
medication
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Typical symptoms include recurrent episodes of
breathlessness
wheezing,
cough.
chest tightness
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Common precipitants include
exercise, particularly in cold weather,
exposure to airborne allergens
 pollutants
 viral upper respiratory tract infections (beware the cold that 'goes
to the chest' or takes more than 10 days to clear).
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 Moderately
severe cases the patient is
orthopneic,cyanosed, and accessory muscles of
respiration are active
 Ineffective cough with tenacious mucoid
expectoration
 Pulse rapid
 BP normal or elevated
 Pulsus paradoxus in severe cases
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 Chest
expansion diminished ie,less than 2cm
during attack.
 Expiratory wheeze heard all over the chest.
 Patients with mild intermittent asthma are usually
asymptomatic between exacerbations which occur
during viral respiratory tract infections or after
exposure to allergens.
 In persistent asthma the pattern is one of chronic
wheeze and breathlessness
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a
diurnal pattern, symptoms being worse in the
early morning.
 Particularly when asthma is poorly controlled,
symptoms such as cough and wheeze disturb
sleep and have led to the use of the term 'nocturnal
asthma'.
 Cough may be the dominant symptom in some
patients and the lack of wheeze or breathlessness
may lead to a delay in reaching the diagnosis of
so-called 'cough-variant asthma'.
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Occupational
asthma is now the most common
form of occupational respiratory disorder and
accounts for around 5% of all adult-onset asthma.
This should be considered in all adult
asthmatics of working age, particularly if symptoms
improve during time away from work, e.g.
weekends or holidays.
Atopic individuals and smokers appear to be at
increased risk.
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 Early
diagnosis and removal from exposure leads
to a significantly improved prognosis and may
result in cure.
 The recognition of occupational asthma has
important medico-legal implications and should
prompt screening of the workplace and other
employees .
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 The
diagnosis of asthma is made on the basis of a compatible
clinical history combined with the demonstration of variable airflow
obstruction
 Eosinophilia
 Sputum reveals eosinophils.
 Sputum shows eosinophils, mucus plugs and curschmann’s spirals.
 Purulent sputum indicative of respiratory infection.
 Culture reveals the infecting organisms
 Pulmonary function tests
 Compatible clinical history plus either/or:
 FEV1 ≥ 15% (and 200 ml) increase following administration of a
bronchodilator/trial of corticosteroids
 > 20% diurnal variation on ≥ 3 days in a week
 FEV1 ≥ 15% decrease after 6 mins of exercise
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 Acute
asthma is accompanied by hyperinflation,
 lobar collapse may be seen if mucus has occluded
a large bronchus.
 Flitting infiltrates, on occasion accompanied by
lobar collapse, suggest asthma complicated by
allergic bronchopulmonary aspergillosis (ABPA).
 An HRCT scan may be useful to detect
bronchiectasis
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An
elevated sputum or peripheral blood eosinophil
count may be observed.
The serum total IgE is typically elevated in atopic
asthma.
Skin prick tests are simple and provide a rapid
assessment of atopy.
Measurement of allergen-specific IgE.
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Induced
sputum and exhaled breath allow the noninvasive assessment of airway inflammation and
may prove useful in the diagnosis of asthma and
assist in the monitoring of disease activity.
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Achieve
and maintain control of symptoms
Prevent asthma exacerbations
Maintain pulmonary function as close to normal as
possible
Avoid adverse effects from asthma medications
Prevent development of irreversible airflow limitation
Prevent asthma mortality
Patient education
Avoidance of aggravating factors
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 PEF
33-50% predicted (< 100 l/min)
 SpO2 < 92% or PaO2 < 8 kPa (60 mmHg) (especially if
being treated with oxygen)
 Normal PaCO2
 Silent chest
 Cyanosis
 Feeble respiratory effort
 Bradycardia or arrhythmias
 Hypotension
 Exhaustion
 Confusion
 Coma
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 PEF
33-50% predicted (< 200 l/min)
 Respiratory rate ≥ 25/min
 Heart rate ≥ 110/min
 Inability to complete sentences in 1 breath
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 Bronchitis
 Bronchiectasis
 Pulmonary
fibrosis
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