• DIAGNOSING ASTHMA IN GENERAL PRACTICE
• WHAT IS ASTHMA?
• ARRIVING AT A DIAGNOSIS
• DIAGNOSIS IN INFANTS AND CHILDREN YOUNGER THAN 5 YEARS OF AGE
• IDENTIFYING THE HIGH-RISK PATIENT

Despite fruitful research over the last 20 years, why is it that asthma prevalence (especially in children) is still on the rise? The answer is that, as always in the past, asthma still continues to be underdiagnosed and undertreated.

In our country, asthma continues to be often ‘diagnosed’ (in adults and children) as ‘asthmatic bronchitis’, ‘wheezy bronchitis’, or ‘allergic bronchitis’. Fear of labelling a patient as ‘asthmatic’ still hounds our general practitioners, physicians, and paediatricians. Firstly, the doctor fears that the patient (or parent, in the case of a child) may be alarmed and unwilling to accept the diagnosis. Secondly, the doctor fears that the patient may change doctors (which, in India, happens at the drop of a hat!; and more so, when unwilling to accept a diagnosis).

It is primarily due to the above reasons that the rates of asthma incidence and mortality have increased or remained stable over the last decade in spite of recent advances in asthma prevention and management. Asthma practice patterns have not kept pace in translating these advances in prevention and management into actual asthma care delivery. Underdiagnosis and inappropriate therapy are major contributors to asthma morbidity and mortality.

Some readers will be surprised at how ‘addicted’ ‘a well-treated asthmatic can become to his doctor. Rarely have I seen a more grateful patient than the one whose undiagnosed asthma has been diagnosed and treated. Regular prophylactic treatment (usually with inhaled steroids) results in freedom from symptoms, virtually no exacerbations, and an improved quality of life, similar to that enjoyed by normal people.

The following review will focus on the new understanding and diagnosis of asthma. It is critical that asthma be diagnosed early and appropriate therapy instituted quickly. So many people in this country are awaiting diagnosis and are unaware that their lives can be normal and active and that this transformation is so close.

Airflow obstruction in asthma is the result of:

• Contraction of the airway smooth muscle and
• Airway inflammation characterised by:

1. mucus hypersecretion
2. mucosal oedema
3. cell infiltration
4. epithelial desquamation

In the long term, this inflammatory process can cause permanent changes in the airways.

If patients understand that asthma is caused by more than bronchospasm, they will appreciate the need for two separate types of medication for asthma management:

• Bronchodilator (also referred to as ‘reliever’) medication and
• Anti-inflammatory (also referred to as ‘preventer’) medication

The diagnosis of asthma is based on:

1. History
2. Physical examination
3. Supportive diagnostic testing

Where the diagnosis of asthma has not been made before, the characteristic symptoms which suggest it are:

Wheeze, chest tightness, shortness of breath and cough; especially if these symptoms are recurrent, worse at night or in the early morning, or obviously triggered by exercise, irritants, allergens or viral infections.

However, the symptoms and signs of asthma vary widely from patient to patient and the absence of typical symptoms does not exclude the diagnosis of asthma.

A chronic or recurring cough may be the only symptom of asthma.
Asthma is the most common cause of a persistent night cough.

The following questions must be asked when noting the patient’s history:

• Has the patient had an attack or recurrent episodes of wheezing (high-pitched whistling sounds when breathing out)?
• Does the patient have a troublesome cough, worse particularly at night, or when awakening?
• Does the patient (esp. child) cough after physical activity, like running or other exercise?
• Does the patient have breathing problems during a particular season?
• Do the patient’s colds ‘go to the chest’ or take more than 10 days to resolve?
• Does the patient use any medication (e.g. bronchodilator or corticosteroid) when symptoms occur? Is there a response?

  If the patient answers ‘yes’ to any of the above questions, a diagnosis of asthma should be considered.

  Some more important questions that must be additionally asked and can give clues to a more specific diagnosis include:

• Are the symptoms (of cough and/or wheeze) more during working days of the week and less or absent on holidays? (suggestive of occupational asthma)
• Are the symptoms related to asthma usually triggered off by a cold? (suggests asthma linked to allergic rhinitis)
• Are the symptoms of asthma often worse after meals? (suggest gastroesophageal reflux-induced asthma)
• Are symptoms of asthma triggered or worse after use of pain killer medicine, e.g. aspirin etc? (could suggest NSAID-induced asthma)
• Are you hypertensive? (look for -blocker induced asthma)

  ASTHMA MEDICAL HISTORY CHECKLIST:

  Factors which may induce or aggravate (trigger asthma)

• Exposure to known allergen (e.g. cockroach, pollens, moulds)
• Viral respiratory infections
• Exercise
• Animals with fur or feathers
• House-dust mites (in mattresses, pillows, upholstered furniture, thick curtains, carpets)
• Smoke (tobacco, wood, agarbattis)
• Changes in weather, exposure to cool air
• Emotions such as laughing or crying loud
• Drugs, e.g. aspirin and beta blockers
• Foods, especially nuts
• Food additives - colourings, metabisulphite, monosodium glutamate
• Exposure to irritants - e.g. strong odours, perfume
• Gastro-oesophageal reflux, allergic rhinitis or sinusitis
• Exposure to chemicals or other occupational sensitisers
• Menses

  REMEMBER:

• Recurrent episodes of coughing or wheezing are almost always due to asthma in both children and adults.
• A chronic or recurring cough may be the only symptom of asthma.
• Asthma is the most common cause of a persistent night cough.

An asthma patient may present to a physician either with the first episode of symptoms or after chronic, recurring symptoms. Most patients present initially to their general practitioner and it is here that a diagnosis can be arrived at and appropriate management instituted.

Physical signs may be present if the patient has symptoms at the time of examination. Absence of physical signs does not exclude a diagnosis of asthma.

Because asthma symptoms vary throughout the day, the respiratory system may appear normal during physical examination. Thus the absence of symptoms at the time of the examination does not exclude the diagnosis of asthma. Therefore, clinical signs, which include the following, are more likely to be present when a patient is experiencing symptoms.

Cough

1. Usually chronic or recurring
2. More pronounced when asked to exhale forcefully
3. Often associated with chest tightness
4. Increased while patient is talking or laughing
5. Often expectorates thick, mucus plugs after a violent bout of coughing
6. Much worse when asked to lie down or blow into a peak flow meter

   Wheeze - high-pitched whistling sound while breathing (usually complained by the patient, and can be heard without the stethoscope in patients with severe bronchospasm)

   Dyspnoea (breathing difficulty)

7. Rhonchi (heard with a stethscope), more pronounced during expiration
8. Flaring of the nostrils when breathing in
9. Interrupted talking
10. Agitation
11. Use of accessory muscles, hunching forward, or preferring not to lie down.
12. Silent chest (i.e. no audible rhonchi with stethoscope in acute, severe asthma).

    Increased nasal secretions, sinusitis, rhinitis or nasal polyps (often seen in allergic rhinitis associated with asthma).

    Allergic skin rashes, eczemas (seen in atopic dermatitis associated with asthma)

    It is equally important to realise that all that wheezes is not asthma. Wheezing may often be seen in conditions other than asthma. Asthma can be differentiated from such conditions (see table that follows).
    

Chronic bronchitis

usually elderly; cigarette smokers; poor reversibility in lung function

Bronchiectasis

Vocal cord paralysis or dysfunction

Foreign bodies

Endobronchial tumours

Congestive heart failure

Pulmonary embolism

Pneumonia

The diagnosis of asthma can be confirmed by demonstrating the presence of reversible airway obstruction. The most common tests are spirometry and peak expiratory flow rate (PEFR) measurement. Most adults and children over 5-6 years of age can perform spirometric tests.

Spirometry:
Just like electrocardiograms (ECGs) are used to determine the functioning of the heart, spirometry is needed to determine the level of lung function. An X-Ray Chest tells you a lot about the gross structure and pathology of the lung, but little about its functioning capabilities.

Spirometry is strongly recommended for all those who can perform the test.

Certain terms to understand (FVC, FEV₁ and FEF_25-75%)

FVC: (Forced Vital Capacity). This is the maximum volume of air that can be forcefully exhaled after a maximal inspiration.

FEV₁: (Forced Expiratory Volume in the 1st second). The forced volume of air that can be expired in the first second of an FVC manoeuvre is the single best measure of lung function for assessing airflow limitation or asthma severity. A diagnosis of asthma can be made with confidence when:

FEV₁ increases by 15% or more than 200 mL after bronchodilator use

Spirometers, however, may be cumbersome and expensive to use. Hence they are presently primarily used in the clinic and hospital settings for diagnosis and long-term monitoring of asthma.

FEF_25-75%: (Forced Expiratory Flow _25-75%). This is the average expired flow over the middle half of the FVC manoeuvre and is regarded as a more sensitive measure of small airways narrowing than FEV₁. However, it is less reproducible than FEV₁ and difficult to interpret when the FVC is reduced.

1) Normal spirometry

2) FEV₁ <80% FVC

3) FEV₁ increase by 15% or more than 200 mL after bronchodilator

4) FEF_25-75% reduced

Spirometry should not be done in the following conditions:

• Haemoptysis
• Respiratory infection on the day of test
• Chest pain, or pain induced or aggravated by testing

Peak Expiratory Flow Rate:
Peak expiratory flow rate (PEFR) is the fastest rate at which air can move through the airways during a forced expiration starting with fully inflated lungs. Peak flow meters are used to measure the PEFR. PEFR correlates fairly well with FEV₁. Peak flow meters are small, portable, convenient and inexpensive.

Peak flow meters are much simpler to use on a clinic basis. In fact, just like a thermometer or sphygmomanometer, the PEFR provides an objective assessment of asthma control.

Simple Steps on How to Use a Peak Flow Meter:

1. Fit the mouthpiece to the peak flow meter
2. Ensure the patient stands up and holds the peak flow meter horizontally. Adjust the pointer to zero
3. Nose clips are unnecessary. Ask the patient to breathe in deeply (as far as possible) with the  mouth wide open. Place the mouthpiece in the mouth and ask the patient to seal his/her lips around it
4. Ask the patient to blow out as hard and fast as possible. In case the patient coughs, disregard that reading. Make sure that the patient’s tongue is not blocking the mouthpiece. Record the result
5. Make the patient repeat steps 2 to 4 two more times and record the highest of the three readings

   A child should be told to blow out vigorously as if blowing out candles on his birthday cake

   A diagnosis of asthma is possible if:

• There is a significant (> 15%) increase in PEFR after inhaled short-acting b₂-agonist (or there is an increase in PEFR after a trial therapy with short-acting b₂-agonist and corticosteroid).
• There is abnormal PEFR variability. A variation of > 20% between morning and evening readings indicates asthma in patients taking a bronchodilator (> 10% in patients who are not taking a bronchodilator).
• There is a 15% decrease in PEFR after running or other exercise.

  Monitoring of the peak flow rates is extremely useful whenever the patient comes for a review. This helps to ascertain the patient’s ‘personal best’ PEFR. When the patient is asymptomatic and normal on clinical examination, this is probably the time one would expect a ‘personal best’ reading. The ‘personal best’ reading provides an excellent guide to monitoring. Maintaining the patient within 20% of his/her personal best reading has important uses:

1. It serves as an objective tool to tell the patient that all is well with the asthma, despite having symptoms (probably related to infection or other causes).
2. It helps the doctor to make decisions on reducing or increasing prophylactic therapy. Maintaining personal best readings for 3-6 months would certainly justify a reduction in dose of prophylactic treatment. Similarly, deteriorating PEFRs would alert the doctor to:

1. Identify any new triggers
2. Check compliance with prophylactic therapy
3. Increase the dose of prophylactic medication

3. If the patient uses a peak flow meter at home, the doctor can guide him/her for cut-off readings, which may serve as early warning signals of an asthma attack.

   Beware of over-treatment based on a poorly performed PEFR reading.

   In the case of infants and young children who are unable to use a spirometer or a peak flow meter reliably, a therapeutic trial with bronchodilator and/or corticosteroid may support the diagnosis.

   Other Tests:

   Chest X-Ray

4. If the diagnosis is uncertain
5. There are symptoms not explained by asthma
6. There is physical evidence of a complication like alelectasis, pneumothorax or failure to respond to treatment

   Bronchial Challenge (e.g. histamine, methacholine)

   Bronchoprovocation tests are done at some specialised centres where facilities are available. These may help to confirm the diagnosis when symptoms present are suggestive of asthma, but the spirometry is still normal.

   Allergy Tests

   Some patients may benefit from assessments of their allergic status by skin tests or specific IgE in serum. Positive allergy test results will not add to the diagnosis of asthma, but when correlated with patient history, they may identify asthma triggers and help in developing effective management plans.

   Gastroesophageal reflux assessment

   Many patients with asthma have their symptoms aggravated by gastroesophageal reflux. Anti-reflux measures often help to reduce their symptoms. Precise determination of GE-reflux needs the measurement of oesophageal pH. An empirical trial of anti-reflux measures usually suffices and such a detailed assessment is rarely required.
   

Because children with asthma are often mislabelled as having bronchiolitis, bronchitis, or pneumonia, many do not receive adequate therapy.

• The diagnostic steps listed previously are the same for this age group except that spirometry is not possible. A trial of asthma medications (bronchodilators/corticosteroids) may aid in the eventual diagnosis.
• Diagnosis is not needed to begin to treat wheezing associated with an upper respiratory viral infection, which is the most common precipitant of wheezing in this age group. Patients should be monitored carefully.
• There are two general patterns of illness in infants and children who have wheezing with acute viral upper respiratory infections: a remission of symptoms in the pre-school years and persistence of asthma throughout childhood. The factors associated with continuing asthma are allergies, a family history of asthma, and perinatal exposure to aeroallergens and passive smoking.

The following characteristics identify the patient who is potentially at risk from life-threatening asthma and indicate the need for close follow-up.

• Frequent visits to Emergency Room or general practitioner with acute asthma, or hospital admission for asthma in previous 12 months.
• A history of admission to Intensive Care or a previous near-fatal attack.
• Night-time attacks, especially associated with severe chest tightness or ‘choking’.
• Marked (> 25%) diurnal variation in peak expiratory flow.
• Immediate hypersensitivity to foods - especially allergy to nuts.
• Sensitivity to aspirin or other non-steroidal anti-inflammatory drugs (NSAIDs).
• Inadequate treatment or poor compliance with treatment.
• Failure to perceive asthma symptoms when lung function is impaired, as shown by spirometry or peak flow results.
• Excessive reliance on inhaled oral bronchodilators.
• Denial of asthma overt or psychosocial problems.

  DIAGNOSTIC CHALLENGES IN ASTHMA

• Young children whose primary symptom is cough or who wheeze with respiratory infections are often misdiagnosed as having bronchitis or pneumonia (including acute respiratory infection-ARI) and thus ineffectively treated with antibiotics or cough suppressants. Treatment with asthma medication can be beneficial and diagnostic.
• Many infants and young children who wheeze with viral respiratory infections may not develop asthma that persists through childhood. But they may benefit from asthma medications for their wheezing episodes. There is no certain way to predict which children will have persistent asthma, but allergy, a family history of allergy or asthma, and perinatal exposure to passive smoking and allergens are more strongly associated with continuing asthma.
• Asthma should be considered if the patient’s colds repeatedly "go to the chest" or take more than 10 days to clear up, or if the patient improves when asthma medication is given.
• Tobacco smokers and elderly patients frequently suffer from chronic obstructive pulmonary disease with symptoms similar to asthma. Yet they may also have asthma and benefit from treatment. Improvements in PEF after asthma treatment is diagnostic.
• Workers who are exposed to inhalant chemicals or allergens in the workplace can develop asthma and may be misdiagnosed as having chronic bronchitis or chronic obstructive pulmonary disease. Early recognition (PEF measurements at work and home), strict avoidance of further exposure, and early treatment is essential.
• Asthma attacks may be difficult to diagnose. For example, acute shortness of breath, chest tightness and wheezing can also be caused by croup, bronchitis, heart attacks, and vocal chord dysfunction. Using spirometry, establishing reversibility of symptoms with bronchodilators, and assessing the history of the attack (e.g. whether it was related to exposures that commonly make asthma worse) aid the diagnosis. A chest X-ray can help rule out infection, airway lesions, congestive heart failure, or aspiration of a foreign object.

  Further Reading

1. International Consensus Report on Diagnosis and Treatment of Asthma; NHLBI, NIH. European Respiratory Journal 1992; 5: 601-41
2. Asthma Management Handbook 1996, National Asthma Campaign, Melbourne, Australia.
3. Expert Panel Report 2: Guidelines for the Diagnosis and Management of Asthma, National Institute of Health, NHLB, No. 97; 97-4053, October 1997.
4. Spirometry: The Measurement and Interpretation of Ventilatory Function in Clinical Practice. Pierce R and Johns DP. Thoracic Society of Australia and New Zealand.
5. Pulmonary Function Testing for Clinicians, Virendra Singh, 1999 Indian Asthma Care Society, Jaipur, India.