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Results from inflam à
hyper-responsiveness of bronchi à
bronchoconstriction.
In the vast majority of cases, disease is mild & often
unrecognizable.
Prevalence ↑, esp. in 2nd decade, reason
(?).
Clinical Features:
Symptoms often worse at night:
1.
Cough.
2.
Wheeze.
3.
Chest tightness.
4.
Dyspnea, particularly exhalation.
Pathology
Bronchus
Sputum:
q
Curschmann’s
spirals:
appear as small white granules.
q
Charcot-Leyden crystals:
Etiology
External:
early onset, in atopic individuals who have (+) skin test &
FHx.
Intrinsic:
q
Late onset in non-atopic individuals.
q
> Refractory to
Rx; often follows severe respiratory illness.
Factors provoking attacks of asthma:
1.
Allergens:
Pollens, dust mites, cockroach,
animal dander, feathers.
2.
Drugs:
β-antagonists,
Aspirin.
3.
Foods:
nuts.
4.
Infection:
viral in children.
5.
Environmental:
Chemicals, air pollution, weather (cold / hot air / humidity), fumes,
irritants.
6.
Emotional
stress.
q
Persistent.
q
Episodic.
q
Occupational.
q
Aspirin-induced.
q
Steroid resistant.
q
Pregnancy.
q
Nocturnal.
Investigations
1.
Pulmonary
Flow Tests:
◙
FEV1, FVC (Reversibility test)
q
To determine:
o
Degree of airflow
obstruction.
o
To what extent it can
be relieved by bronchodilator drugs.
q
Confirm that
abnormality is provoked by exercise / occupation.
◙
PEF:
q
Serial recordings.
q
Monitors & treat
chronic & acute attacks.
◙
Measurement of bronchial reactivity to histamine &
methacholine by gradual inhalation until there is a 20% fall in
FEV1 (called PD20 = Provocative Dose).
2.
Arterial
Blood Gases analysis.
3.
Skin
hypersensitivity test.
4.
CXR
& sputum test for eosinophils.
Management
1.
Assessment of severity:
|
Severity
|
Symptoms
|
|
Mild
Moderate
Severe
Very
severe
|
à
< Weekly.
à
Most days.
à
Waking at night.
à
Recently in hospital.
|
2.
Pharmacolgic therapy.
3.
Avoidance
of provocative factors.
Cx
q
Repeated attacks à
Chronic bronchitic condition à
Emphysema.
q
Status asthmaticus.
Severe acute asthma = Status asthmaticus
q
Life-threatening.
q
Patient usually adopts upright position fixing
shoulder girdle to assist accessory muscles of respiration.
Immediate
assessment of acute severe asthma
v
Features
of severity
o
Pulse
rate > 120/ min
o
Pulsus
paradoxus.
o
Unable
to speak in sentences.
o
Peak
flow < 50% of expected.
v
Life-threatening
features:
o
Can’t
speak!
o
Central
cyanosis.
o
Exhaustion,
confusion, consciousness.
o
Bradycardia.
o
‘Silent
chest’
o
Unrecordable
PF.
Management
of acute severe asthma
1.
↑
[O2].
2.
↑ Doses of
inhaled short acting β2-adrenoceptor
agonists. e.g. salbutamol
/ terbutaline.
q
In early acute attack, ↑ inhaled
corticosteroids might be sufficient.
q
Amino-phylline
infusion.
q
Mechanical ventilation
if patient fails to respond.
written
by:
Khalid Bin Yaroof. FMHS, UAE University.
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