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How is asthma diagnosed?
All those who
wheeze are not asthmatic and all asthmatics do not wheeze.
Therefore diagnosis of asthma is very important for the
proper treatment of asthma.
To establish
a diagnosis of asthma, the clinician should determine that:
Episodic symptoms of airflow obstruction or airway
hyperresponsiveness are present.
Airflow obstruction is at least partially reversible.
Alternative diagnoses are excluded.
Recommended methods to establish the diagnosis are:
Detailed medical history.
Physical exam focusing on the upper respiratory tract, chest,
and skin.
Spirometry to demonstrate obstruction and assess
reversibility, including in children
5 years of age or older. Reversibility is determined either by an increase in FEV1 of
≥12 percent from baseline or by an increase ≥10 percent of predicted FEV1 after inhalation of a short-acting bronchodilator.
Additional studies as necessary to exclude alternate
diagnoses.
Diagnosis of
asthma involves:
1.
Detailed medical history,
2. Physical examination,
3. Investigations like spirometry, X-ray chest-PAV.
Medical
history:
-
Doctors ask
about the family history of asthma, allergies including
allergic rhinitis, eczema.
-
Children who
have family history of allergies, asthma have greater chances
of having asthma.
-
History of
recurrent and persistent cough and cold following exposure to
cold air, changing seasons.
-
Exercise limited
by breathing problem and wheezing
-
Occupational
history for exposure to gases, fumes, chemicals etc.
-
Any history of
emergency room visits or hospitalization following breathing
problem.
-
In the children
diagnosis is mainly clinical. Doctor determines when the
parents first noticed child developing breathing problem,
itchy eyes, nasal stiffness, eczema.
Asthma diagnosis is
suspected in all adult and children whose have following sign
and symptoms:
-
Recurrent Wheeze
which is a high-pitched whistling sounds when breathing
out—especially in children. (Lack of wheezing and a normal
chest examination do not exclude asthma.)
-
Cough, worse particularly at
night
-
Recurrent
breathlessness or difficulty in breathing
-
Recurrent
chest tightness
-
Recurrent lower
respiratory tract infections (LRTI)
-
Exercise induced cough/wheeze
Physical
examination:
Physical
examination includes listening to breath sounds over the chest
for possible ronchi or wheeze or rales, examination of nasal passage for evidence
of allergic rhinitis like nasal polyps and deviated nasal
septum.
Peak flow
meter:
Peak flow meter is a small portable hand held instrument used to
measure peak flow rates, or how well the airways are open.
Asthma is suspected when there is more than 20% diurnal
variation on 3 days or more in a week or for 2 weeks in a PEF
diary.
For more information click Peak Flow Meter
Lung function testing (Spirometry):
If symptoms and the patients history points towards the
diagnosis of asthma, the physician will perform
spirometry
or lung function test to
confirm the diagnosis of asthma.
Spirometry is used to access the airflow obstruction. For
asthma diagnosis airflow obstruction should be at least
partially reversible.
To establish airflow obstruction physician uses spirometer to
measure (FEV1, FVC, FEV1/FVC) before and after the patient
inhales a short-acting bronchodilator.
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