Clinical Notes : Paediatrics

8. Bronchiolitis


  • Approximately one third of all infants develop bronchiolitis in the first 2 years of life

  • Peak incidence at 6-12 months

  • 2-3% of which require hospital admission



  • 75% of bronchiolitis is due to respiratory syncytial virus, the rest due to other common respiratory viruses




Coryzal symptoms for 1-3 days followed by

  • Persistent cough, AND

  • Tachypnoea and/or chest recession, AND

  • Wheeze and/or crackles on chest auscultation


Fine crackles (rales)

Fine crackles are brief, discontinuous, popping lung sounds that are high-pitched.

Fine crackles are also similar to the sound of wood burning in a fireplace, or hook and loop fasteners being pulled apart or cellophane being crumpled.

Crackles, previously termed rales, can be heard in both phases of respiration.

Early inspiratory and expiratory crackles are the hallmark of chronic bronchitis and bronchiolitis. .

Fine crackles (rales) -

Coarse crackles (rales)

Coarse crackles are discontinuous, brief, popping lung sounds.

Compared to fine crackles they are louder, lower in pitch and last longer.

They have also been described as a bubbling sound.

You can simulate this sound by rolling strands of hair between your fingers near your ear.

Late and coarse inspiratory crackles may mean pneumonia, CHF, or atelectasis

Coarse crackles (rales) -

Chest auscultation findings associated with bronchiolitis vary according to age, with infants older than 24 weeks likely to present with wheeze and those younger than 16 weeks more likely to present without auscultatory chest signs.

This is a crucial finding as it is commonly held misconception that crackles are a consistent feature of bronchiolitis.

Expiratory wheeze

Wheezes are adventitious lung sounds that are continuous with a musical quality.

Wheezes can be high or low pitched. High pitched wheezes may have an auscultation sound similar to squeaking.

Lower pitched wheezes have a snoring or moaning quality.

The proportion of the respiratory cycle occupied by the wheeze roughly corresponds to the degree of airway obstruction.

Wheezes are caused by narrowing of the airways.

Expiratory wheeze -

Monophonic wheeze

Monophonic wheezes are loud, continuous sounds occurring in inspiration, expiration or throughout the respiratory cycle.

The constant pitch of these sounds creates a musical tone.

The tone is lower in pitch compared to other adventitious breath sounds. The single tone suggests the narrowing of a larger airway.

These lung sounds are heard over anterior, posterior and lateral chest walls.

These sounds can be more intense over lung areas affected by partial obstructions.

Monophonic wheeze -

Assessment (record all findings)

Fluctuating clinical findings are a hallmark of bronchiolitis

  • Measure temperature, heart rate, respiratory rate, capillary refill time

    • Infants with bronchiolitis are rarely “toxic”

  • Looks for signs of respiratory distress

    • recession, nasal flaring, exhaustion

    • Fever >39C is unusual, consider pneumonia / alternative diagnosis

    • Apnoea may be the presenting feature in very young children (especially <6wk old)

  • Check for dehydration

    • Ask about oral intake and wet nappies

    • Poor feeding (most common days 3-5)

  • Check oxygen saturations if a paediatric Sats probe is available


Refer to A+E / paeds  if

  • NICE traffic light system amber or red

  • Significant co-morbidities, e.g. cardiac/respiratory disease

  • Age <3 months

  • Premature infants born <35 weeks gestation

When considering referral, remember that symptoms increase over the first 3 days and peak at 3-5 days.


Management at home (green NICE traffic light)

  • Take into account the capability of the carer / parent when deciding on follow up and referral

    • Antibiotics, inhalers, nebulisers, steroids and montelukast are not helpful and should not be prescribed

    • There is some evidence that nebulised saline solution is of benefit

    • Antipyretics are only recommended in the presence of fever and distress

    • No evidence that aerosols/steams.mists are of benefit

  • Inform parents that bronchiolitis can deteriorate and discuss red flags which should prompt review

    • Worsening work of breathing

    • Fluid intake is 50-75% of normal or no wet nappy for 12 hours

    • Apnoea or cyanosis

    • Exhaustiion

  • If the child is miserable due to a temp consider antipyretics

  • Encourage feeding regularly and maintain fluid intake

  • Inform parents that bronchiolitis can can deteriorate and discuss red flags which should prompt review

    • Worsening work of breathing

    • Fluid intake is 50-75% of normal or no wet nappy for 12 hours

    • Apnoea and cyanosis

    • Exhaustion

  • Inform parents of expected resolution time-frame

    • Symptoms usually peak at day 3-5

    • 50% of infants are asymptomatic at 2 weeks

    • Cough resolves in 90% by 3 week

    • A minority may have symptoms at 4 weeks

  • Encourage parents to :

    • Wash hands frequently with soap and water

    • Avoid other adults and children with upper respiratory infection

    • Avoid passive smoking (outcomes are worse in these children)

  • Arrange GP follow-up

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BMJ Best Practice

Last Reviewed September 2019

Last Updated  January 2019


Schroeder AR, Mansbach JM, Stevenson M, et al.

Apnea in children hospitalized with bronchiolitis.

Pediatrics. 2013 Nov;132(5):e1194-201.


Ralston SL, Lieberthal AS, Meissner HC, et al;

American Academy of Pediatrics.

Clinical practice guideline: the diagnosis, management, and prevention of bronchiolitis.

Pediatrics. 2014 Nov;134(5):e1474-502.


Friedman JN, Rieder MJ, Walton JM, 

Canadian Paediatric Society

Bronchiolitis : Recommendations for diagnosis, mnitoring and management of children one to 24 months of age

Updated 31 Jan 2018


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