Diagnosis of Asthma

What are the Diagnostic Criteria of Asthma?

There are four diagnostic criteria of asthma:

1. Cardinal features of asthma

• Paroxysmal respiratory distress
• Recurrent cough
• Wheeze
• Chest tightness

2. Recurrent attack due to multiple stimuli

3. Features of Eosinophilic inflammation: Sputum Eosinophilia

4. PFT: obstructive defects, at least partially reversible by drug

In case of children under five years of age 7. Exclusion of other differential diagnoses

sputum may not be available for examination and pulmonary function test may not be possible. So, for childhood asthma.

5. Family history of allergy (family allergy score is > 4)

6. Presence of other concomitant atopic illnesses:

• Atopic Dermatitis (Eczema)
• Allergic rhinitis
• Allergic conjunctivitis

If a child with positive family history of bronchial asthma (i.e. asthma among first relations) suffers from brochiolitis with subsequent recurrent wheeze and/or cough, he/she should be given preventive treatment of bronchial asthma with anti-inflammatory medicines (cromones/corticosteroids), for about 6 months after last episode of wheezing and/or coughing.

What are the differential diagnosis of asthma?

In Adult: There are some major diseases that should be excluded from asthma. These conditions may also present concomitantly with asthma.

i. COPD

ii. CCF (Previously termed as Cardiac Asthma)

iii. Pulmonary Eosinophilia

iv. Mechanical obstruction by tumour etc.

v. Pulmonary tuberculosis

vi. Interstitial lung diseases

vii. Bronchiectasis

viii. Gastro esophageal reflux disease

ix. Post nasal drip syndrome

In Child : There are few childhood diseases that should be differentiated from asthma.

i. Viral bronchiolitis

ii. Gastro esophageal reflux disease

iii. Pulmonary Tuberculosis

iv Laryngotracheomalasia

v. Pneumonia (Recurrent)

vi. Congenital heart disease

vii. Bronchiectasis

viii. Foreign body in the airway

ix. Cystic fibrosis

x. Post nasal drip syndrome

xi. Happy wheezers

Differential diagnosis of childhood asthma

Bronchiolitis: Commonest infection, peak age 2-6 months, caused mostly by RSV virus, good health, preceding coryza, low grade fever, feeding difficulty, dyspnoea, tachypnoea, chest recession, cyanosis, wheeze, crackles, palpable liver and spleen as the hyperinflated chest pushes the diaphragm downwards, CXR shows hyperluscent lung fields, wheeze and hypoxia may last as long as three to four weeks.

Gastro-esophageal reflux disease (GERD): Should be considered in children with inadequately explained chronic cough, may result either from the presence of gastric contents in the hypopharynx or due to the irritation of lower esophageal receptors. Effortless vomiting after meals, recurrent cough, recurrent pneumonia, anemia, barium meal study, 24-hour esophageal pH study and isotope milk scan may help in diagnosis.

Pulmonary tuberculosis: H/O contact with TB patients, chronic illness, cough, failure to thrive, CXR showing patchy opacities suggestive of Koch’s infection, hilar adenopathy, raised ESR, sometimes positive Mantoux test.

Laryngotracheomalasia: Wheezing, cough, stridor, dyspnoea, tachypnoea and cyanosis. Functional stridor is worst in supine position, in flexed neck, during crying and with respiratory tract infection. Improvement usually noted after 6-12 months with maturity of supporting cartilages.

Recurrent pneumonia: Fever, tachypnea, ill health, crepitation on lung fields, CXR shows wooly opacities in both lung fields, repeated attacks, may be associated immunodeficiency or congenital lung problem.

Congestive heart failure: Evidence of commonly congenital or rarely acquired heart disease, tachypnea, tachycardia, chest indrawing, hepatomegaly, peripheral edema (periorbital puffiness, pitting of the dorsal surface of hands and feet), engorged neck vein in older children.

Bronchiectasis: Chronic productive fetid cough, inspiratory crackles over the affected area, clubbed fingers and growth failure. CXR shows multiple ring or rail line like densities. CT scan of chest confirms diagnosis.

Cystic fibrosis: Consanguineous parents, recurrent sinopulmonary infection with or without pancreatic insufficiency (steatorrhoea), failure to thrive and raised levels of sodium and chloride in the sweat as evidenced by sweat test.

Post nasal drip syndrome: Drainage of nasal secretions into oropharynx, nasopharynx and possibly larynx can give rise to chronic cough. Prolonged use of antihistamine (ideally Ketotifen) and Cromolyn nasal drops gives improvement. Decongestants may be used in acute stage.

Happy wheezers: Persistent wheeze, thriving well, well oxygenated, but not responding to bronchodilators. Reassurance is the key point of management. Usually out goes by 1-2 years of age.

Helpful features for the diagnosis of childhood asthma

• Respiratory distress or recurrent wheeze, 3-5 attacks in life resolving either spontaneously or by bronchodilators
• Respiratory distress or wheeze following playing or physical activities
• Chronic night or early morning cough, may awaking the child
• Chronic unproductive cough without apparent cause
• Respiratory distress, wheeze or cough when exposed to dust
• Associated atopic problems of allergic rhinitis, allergic conjunctivitis and atopic dermatitis
• Family H/O asthma is positive
• On auscaltation: Breath sound vesicular with prolonged expiration, Rhonchi present
• CXR : Hyperinflated chest, tubular heart with low flat diaphragm
• Serum IgE level is elevated
• PFT: Air flow obstruction, reversible by bronchodilators

Algorithm for the diagnosis of bronchiolitis, pneumonia and asthma in children

Respiratory Distress

See Also:

Definition of Asthma

Etiology of Asthma

Classification of Asthma

Investigation of Asthma

Medicines of Asthma

Further Reading:

• Asthma and Allergy Foundation of America: http://www.aafa.org/
• American Asthma Foundation: http://www.americanasthmafoundation.org/
• Asthma, UK: http://www.asthma.org.uk/all_about_asthma/index.html