Download Definition

‫د‪ .‬ميريانا البيضة‬
‫‪Asthma‬‬
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DIAGNOSIS
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Definition of asthma
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Definition
The guidelines define
asthma as:
a chronic inflammatory
disease of the airways
many cells play a role
(mast cells, eosinophils,
and T lymphocytes)
Definition
recurrent episodes of:
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•
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Wheezing
Breathlessness
chest tightness
Cough
particularly at night and/or in
the early morning
Definition
widespread but variable
airflow limitation
at least partially reversible
either spontaneously or with
treatment
Definition
increase in airway
hyperresponsiveness to a
variety of stimuli
Definition
• Chronic
Inflammation
• Bronchial
Hyperresponsivenes
s
• Reversible Airway
Obstruction
Confirmation of the diagnosis of
asthma is based on
two key elements:
The history or presence of
respiratory symptoms consistent
with asthma
The demonstration of variable
expiratory airflow obstruction
The variation in expiratory
airflow
may be demonstrated with
measurements made at different
points in time
The variation in expiratory
airflow
or
in response to administration of
anti-asthmatic therapy
The diagnosis of asthma can be
confirmed using several
approaches
depending on the patient's clinical
presentation and clinical course
The 2007 asthma guidelines of the
National Asthma Education and
Prevention Program (NAEPP)
recommend that
spirometry, before and
after administration of a
bronchodilator
be performed in all adolescents and
adults in whom the diagnosis of
asthma is being considered
The use of spirometry or
bronchoprovocation testing to
demonstrate reversible airflow
obstruction is particularly
important when the patient's
symptoms or response to therapy
are not typical
Use of pulmonary function
testing in this manner helps
to prevent both over- and
under-diagnosis of asthma
persons without asthma may have
recurrent cough and chest
congestion
due to
repeated bouts of bronchitis,
episodic chest heaviness due to
gastroesophageal reflux,
or chronic cough due to post-nasal
drip syndrome
In each of these
conditions
repeatedly normal spirometry
or peak flow measurements would
help to
exclude the diagnosis of
asthma.
Conversely
reversible airflow obstruction in
the patient with
chronic cough
but without other chest symptoms
or wheezing on examination
could assist in making the correct
diagnosis of asthma
Diagnosis when
initial PFTs are
normal
Patients with asthma may
have normal lung function at
the time of evaluation.
If the diagnosis is not
apparent based on history
alone
then the following strategies
are useful:
Repeat evaluation by the clinician
when the patient is symptomatic
Repeated patient-based
measurements of PEFR over time,
possibly with a therapeutic trial of
bronchodilator
Bronchoprovocative testing, such as
with a methacholine or exercise
challenge
Serial measurements of
lung function over time
As previously noted, asthma is
characterized by variable
expiratory airflow obstruction.
Normal individuals without asthma
experience little variability
(less than 20 percent)
even when respiratory symptoms
are present.
One useful strategy to diagnose
asthma in patients with normal
lung function at their medical visit
is to provide them with a handheld peak flow meter for home use
and ask that they keep a diary of
their peak flow recordings, as
described previously.
The diagnosis of asthma is
confirmed by a reliable series of
recordings that document
more than 20 percent variability in
PEFR over time
(especially when PEFR reductions
are associated with asthmatic
symptoms)
Similar data collection can take
place in the clinician's office by
recording PEFR or spirometry at
each patient visit.
This method is less dependent on
the reliability of the patient
independently making selfmeasurements, although multiple
visits may be required
Serial patient-recorded
measurements of PEFR over time
can be combined with a
"therapeutic trial" of a
bronchodilator.
Significant decreases in
PEFR that reverse within
minutes of use of an
inhaled beta-adrenergic
agonist
typify asthma.
In individuals without asthma
the increase in PEFR following
bronchodilator administration
would be expected to be
less than 20 percent
Bronchoprovocation
Bronchoprovocation testing
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the diagnosis of asthma can be
confirmed with
bronchoprovocation testing,
usually in the form
of methacholine challenge.
A provocative stimulus
“indirect”
“direct”
• methacholine
and histamine
exercise,
eucapnic voluntary
hyperventilation,
cold air
hyperventilation,
hypertonic saline,
mannitol, adenosine
monophosphate [AMP]
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This diagnostic strategy is
particularly useful for patients
with atypical symptoms
such as isolated
chronic cough.
Standardized protocols for
methacholine testing
The test consists of performing
spirometry at baseline
and then after each dose of nebulized
methacholine
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Diagnosis based on history
and clinical course
In some instances,
the diagnosis is clear because of a
characteristic history and clinical
course.
As an example
the diagnosis is readily made in a
patient who describes repeated
episodes over time of typical
symptoms triggered by typical
stimuli (especially allergic
triggers) and responding to antiasthmatic medications.
in patients presenting to an urgent
care setting or emergency department
the diagnosis can be rapidly made
when asthmatic symptoms
and musical wheezes on
auscultation
resolve over the course of minutes
to hours in response to
bronchodilators and
glucocorticoids
If spirometry is not available, a
diagnosis of probable asthma can
be made based upon history and
response to therapy alone among
patients with classic symptoms
who respond promptly and
completely to therapy.
In patients with less typical or
persistent symptoms,
further evaluation and a more
formal approach to diagnosis is
indicated
Consultation with an asthma
specialist, either a pulmonologist or
an allergist
is warranted
when the diagnosis of asthma is
uncertain,
when the asthma is difficult to
control,
or when a patient has frequent
exacerbations