Armando Hasudungan
Biology and Medicine videos


The presence of a wheeze implies narrowing of airways of any size throughout the proximal conducting airways. Wheezing occurs during the prolonged expiratory phase. Children wheeze more often than adults because of physical differences.

Overview Wheezing in infants and children is a common problem presented to primary care offices. Approximately 25 to 30 percent of infants will have at least one episode of wheezing. The presence of a wheeze implies narrowing of airways of any size throughout the proximal conducting airways. A wheeze requires sufficient airflow to generate the sound of a wheeze. Most infants and children with recurrent wheezing have asthma, but other causes should be considered in the differential diagnosis. Beware of the wheezing patient who suddenly becomes silent.

Wheeze: continous high-pitched whistling expiratory sound
caused by partial upper airway obstruction and is typically heard in inspiration, although it can also be heard on expiration if the obstruction is below the larynx (monophonic)
Stertor: snoring sound
Rhonchi: continuous low pitched, rattling lung sounds that often resemble snoring

Mechanism of Wheeze

  • Occurs during the prolonged expiratory phase by the rapid passage of air through airways that are narrowed to the point of closure.
  • Infants’ and young children’s bronchi are small, resulting in higher peripheral airway resistance → diseases that affect the small airways have a proportionately greater impact on total airway resistance in infants.
  • Infants also have less elastic tissue recoil and fewer collateral airways, resulting in easier obstruction and atelectasis.
  • The rib cage, trachea, and bronchi are also more compliant in infants and young children, and the diaphragm inserts horizontally instead of obliquely.


  • History
    • Onset
    • Pattern
    • Seasonality
    • Cough
    • Position changes
    • Medical history
    • Family History
  • Examination
Remember Beware of the wheezing patient who suddenly becomes silent.
Questions Indications
How old was the patient when the wheezing started? Distinguishes congenital from noncongenital causes
Did the wheezing start suddenly? Foreign body aspiration
Is there a pattern to the wheezing? Episodic: asthma
Persistent: congenital or genetic cause
Is the wheezing associated with a cough? GORD/GERD, sleep apnoea, asthma, allergies
Is the wheezing associated with feeding? GORD/GERD
Is the wheezing associated with multiple respiratory illnesses? Cystic fibrosis, immunodeficiency
Is the wheezing associated with a specific season? Allergies: fall and spring
Croup: fall to winter
RSV: fall to spring

Differentials of wheeze in children


  • FBC
  • Chest X-ray – if unexplained wheezing that is unresponsive to bronchodilators or with recurrent wheezing
  • Bronchoscopy – Immediate bronchoscopy should be performed if foreign body aspiration is suspected
  • Allergy testing
  • Sweat chloride test – cystic fibrosis
  • Serum immunoglobulin levels – Immunodeficient?
  • Barium swallow – may detect vascular rings and esophageal compression.
  • Computed tomography – can identify lung nodules and bronchiectasis, but these are uncommon causes of wheezing in children.
Remember X-ray Features that suggest inhaled foriegn body include: Inspiratory (nothing), Expiratory can reveal gas trapping. If foreign body has been lodged for a long time à atelectasis (rather than gas trapping, due to the reabsorption of the gas). Hyper-inflated lung on opposite non obstructed lung. Tadioopaue ibject may be seen on chest C-ray
Side Note Foreign bodies are revealed in up to 70% of patients

Transient Infant Wheeze Asthma
  • Children with TIW tend to have airways that are of relatively small calibre & may be floppy
  • Maternal smoking is a RF
  • Personal nor FHx of atopy is a RF
  • Benign condition
  • Sx: wheeze – episodic, spontaneous, often increase with viral RTI. Most children outgrow this by 6yo (airways grow in size)
  • Don’t usually respond to bronchodilators
  • Hypersensitive airways that react to allergens à mast cell degranulation à reversible bronchoconstriction
  • RF: Hx of eczema, FHx of asthma, allergic rhinitis
  • Sx: cough, wheeze, secretion production, hyper-inflation, respiratory distress, respiratory failure
  • Bronchoconstriction reverses with beta-2-agonsits

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