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Correct Diagnosis
Making a correct diagnosis is tremendously important because if asthma is correctly diagnosed it can be treated more appropriately.
- A diagnosis of asthma involves all of the following:
- A detailed history which would include:
- A family history of asthma, allergies, hay fever and eczema; children will have a greater chance of developing the above if there is a
family history of allergies and asthma
- A child's medical history including:
- When parents first noticed the child developed breathing problems; history of nasal stuffiness (rhinitis), itchy eyes (allergic
conjunctivitis) and eczema, which are common accompaniments to asthma, and hives (urticaria).
- A history of recurrent and persistent cough following a cold, frequent colds, croup, seasonal changes (i.e. worse in the spring and
autumn), exercise limited by breathing problems, waking at night with symptoms.
- school absences, emergency room visits (hospitalizations)
- environmental history
- Physical examination: i.e. listening to the lungs with a stethoscope; examination of nasal passages etc.
- Chest x-ray to exclude the likelihood of breathing problems being caused by something other than asthma.
- Blood tests and sputum studies.
- Allergy prick skin testing: Skin tests can confirm a presence or absence of allergies; but they must, be correlated to the history of
symptoms shown.
- Spirometry If testing children who are less than five years old, this test is not commonly indicated because a certain amount of effort
and cooperation is required. However, it's a very good trustworthy method of making an asthma diagnosis. Any difficult or troublesome asthma
should be confirmed objectively by performing a spirometry test.
- Challenge tests: Exercise challenge tests and methacholine inhalation tests are procedures which are used most frequently in clinical
laboratories to assess airway responsiveness.
- Differential diagnosis: Other possible causes of shortness of breath, wheeze, and cough plus chest tightness need to be investigated in
order to rule them out. These can include such illnesses as heart disease, other lung conditions and gastro-oesophageal reflux.
- A trial use of asthma medications: If asthma medications are taken and an improvement in symptoms is seen this further supports a
diagnosis of asthma.
Tests may include:
- Peak expiratory flow charts
- Exercise tests
- Histamine or methacholine bronchial provocation test
- A trial of corticosteroids
- Blood and sputum tests
- Chest X-ray
- Skin tests
- Allergen provocation tests
Peak expiratory flow charts Measurements of PEFR on waking, prior to taking a bronchodilator medication and before bed
after a bronchodilator, are very useful in demonstrating the variable airflow limitations characterizing asthma. It's also useful in the
longer-term evaluation of the sufferer's disease and its response to proffered treatment. Peak flows should always be measured over several days
and preferably over a weekend or short holiday if the effect of the asthma sufferer's work exposure is also being studied.
Exercise tests
These are widely used in the diagnosis of asthma in children. Ideally, the child should run for 6 minutes on a treadmill at a workload which is
sufficient to increase their heart rate above 160 beats per minute. Alternative methods use cold air challenge.
Histamine Test This test indicates the presence of airway hyper responsiveness, which is a feature found in most
asthmatics. It can be predominantly useful in investigating those people whose main symptom is a cough.
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