Asthma is a chronic inflammatory disease of the airways in the lungs of children and adults.
The patient usually complains of shortness of breath, chest tightness and coughing with wheezing.

A diagnosis of asthma in young children is more likely if they have symptom patterns, presence of risk factors for development of asthma and therapeutic response to controller treatment.
Goals of treatment are effective symptom control with minimal or no exacerbations, minimal or no nocturnal and daytime symptoms, no limitations on activities, minimal or no need for reliever treatment, and minimal adverse effects of medication.


  • A diagnosis of asthma in children is more likely if they have:
    • Symptom patterns [wheeze, cough, breathlessness (typically manifested by activity limitation), & nocturnal symptoms or awakenings]
    • Presence of risk factors for development of asthma
    • Therapeutic response to controller treatment
    • Episodic symptoms of airflow obstruction or airway hyperresponsiveness
    • Airflow obstruction is at least partially reversible
    • Alternative diagnoses are excluded


  • Identify the symptoms likely to be due to asthma
  • Support the likelihood of asthma (eg patterns of symptoms, family history of asthma & atopic disease)
  • Determine symptom pattern for the past 3-4 months
    • Focus on symptoms that occurred in the past 2 weeks
  • History of variability is essential in the diagnosis of asthma
    • Variability refers to improvement or worsening of symptoms & lung function occurring over a period of time (eg day to day, month to month or seasonally)

Key Indicators for Considering a Diagnosis of Asthma

  • Episodes of wheezing occurring more than once a month or symptoms occur >3 episodes/year
    • Wheezing occurring during sleep, activity, laughing, or crying, & with increasing recurrence is likely due to asthma
  • Activity-induced cough, usually accompanied by wheeze or heavy breathing
  • Nighttime cough or wheeze in the absence of viral infection
  • Heavy breathing, shortness of breath, or difficult breathing during exercise or activity, that is noticeably recurrent increases the likelihood of asthma
  • Persistence of asthma symptoms beyond age 3 year
  • Symptoms triggered or exacerbated by animal fur, aerosol, temperature changes, dust mites, drugs, etc
  • Symptoms (eg cough, wheeze, heavy breathing) lasting longer than 10 days in the presence of an upper respiratory tract infection (URTI)
  • Symptoms improve with asthma medication
  • Presence of patient history or family history of allergic disease (eg atopic dermatitis, allergic rhinitis)

Physical Examination

  • Perform a thorough exam with focus on observation of forced expiration & nasal inspection
  • Hyperexpansion of the thorax
  • Wheezing during normal breathing or prolonged forced exhalation
  • Increased nasal secretion, mucosal swelling or nasal polyps
  • Signs of allergic skin condition
  • Occasionally, wheezing may not be seen in severe asthma attacks due to markedly reduced airflow & ventilation
    • Other signs may be present (eg cyanosis, drowsiness, tachycardia, difficulty speaking)

Laboratory Tests

Allergy Tests

  • Presence of food-specific immunoglobulin E (IgE) &/or atopic dermatitis increases the risk of sensitization to inhaled allergens & may be predictive of developing asthma

In vivo Test

  • Skin prick test

In vitro Test

  • IgE panel test/radioallergosorbent test (RAST)
    • May be done if in vivo test cannot be performed (eg cases of severe dermatitis)
    • May be performed if current antihistamine therapy cannot be discontinued, or if there is a known possibility of a life-threatening reaction to food or inhalant

Asthma diagnosis in children ≤5 years

  • Objective measurements of lung function may be difficult in this age group
  • Atopy is a major risk factor for subsequent development of asthma in this age group & it also predicts severity once asthma develops
  • To help establish a diagnosis of asthma, a diagnostic trial of asthma medications, in addition to a thorough medical history & physical exam, may be useful
  • Consider asthma if >3 episodes of reversible bronchial obstruction have been noted within the last 6 month
    • Patients may have virus-induced asthma which is common in this age group


Pulmonary Function Testing


  • Preferred diagnostic method
    • Measures airflow limitation & determines reversibility
    • All measurements should be done before & after administration of inhaled short-acting bronchodilator
  • Generally valuable in children ≥5 years of age
    • Some children cannot correctly execute the required maneuvers until age 7 years
  • Forced vital capacity (FVC) is a measure of the maximal volume of air exhaled from the point of maximal inhalation
  • Volume of air exhaled during the 1st second of this maneuver is called forced expiratory volume in 1 second (FEV1)
    • FEV1 indicates risk for exacerbations
  • FEV1/FVC appears to be a more sensitive measure of severity of impairment
  • Increase in FEV1 ≥12% after administration of a bronchodilator indicates reversible airflow limitation

Peak Expiratory Flow (PEF) Measurements

  • Important in diagnosis & monitoring of asthma

Bronchodilator Response

  • Determines reversibility of airflow limitation in response to treatment

Fractional Concentration of Exhaled Nitric Oxide (FENO) Measurement

  • Associated with increases in eosinophilic levels
  • An increase in fractional concentration of exhaled nitric oxide (FENO) >4 weeks after an upper respiratory tract infection (URTI) in preschool children with recurrent symptoms may help in the diagnosis & in predicting intranasal corticosteroid use by school-age
  • Further studies are needed to prove the use of fractional concentration of exhaled nitric oxide (FENO) measurement as a guide for adjusting asthma treatment

Other Tests

  • There are several lung function tests that do not rely on patient’s cooperation or the ability to perform the required maneuvers
    • May be valuable in children 2-5 years of age
    • These are not evaluated as diagnostic tests for asthma
    • Commonly used in research studies & specialist centers
    • Eg impulse oscillometry, specific airway resistance, measurements of residual volume
  • Chest radiograph may be used to rule out other pathologies & structural abnormalities
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