Bronchiolitis: Recognise and Assess


Published: 13 June 2022

Bronchiolitis is the most common cause of hospital admission in infants younger than six months. In fact, in Australia, about 13,500 children are admitted to hospital every year due to bronchiolitis (O’Brien et al. 2018).

What is Bronchiolitis?

Bronchiolitis is a viral lower respiratory infection characterised by inflammation and an accumulation of mucus in the bronchioles in the lungs. This causes the bronchioles to narrow, and consequently, results in mild to moderate respiratory distress (Raising Children Network 2020; Justice & Le 2021).

Bronchiolitis is most commonly caused by the respiratory syncytial virus (RSV). Almost every child will experience an RSV infection by the age of two (SA Health 2022).

Other viruses that cause bronchiolitis less commonly include parainfluenza viruses, influenza viruses and adenoviruses (Health.vic 2015). It’s also been suggested that SARS-CoV-2 (the virus that causes COVID-19) can lead to bronchiolitis (Piedra & Stark 2021).

Bronchiolitis most commonly affects infants under six months of age, but may also occur in those up to 12 months old (Better Health Channel 2022).

While older children and adults can be infected by RSV, only infants tend to present with bronchiolitis (SA Health 2022; KidsHealth 2020).

How Does Bronchiolitis Spread?

The viruses causing bronchiolitis are spread by breathing in the respiratory secretions emitted when an infected individual talks, coughs or sneezes. Bronchiolitis can also be transmitted by touching a surface contaminated by a virus and then touching the eyes, nose or mouth (Healthdirect 2020).

Symptoms of Bronchiolitis

bronchiolitis infant with fever

Bronchiolitis typically starts as an acute upper respiratory tract infection. The infant may then begin to experience one or more of the following symptoms:

  • Coughing
  • Tachycardia (rapid breathing) and hypoxia with or without cyanosis
  • Breathing difficulties - the infant may display tracheal tug (the chest sinking in when they attempt to breathe), nasal flaring or head bobbing
  • Nasal flaring
  • Reduced appetite
  • Crackles or wheezing
  • Fever.

(RCHM 2018, 2020; Better Health Channel 2022; RCHSD 2014)

Due to the thick secretions associated with bronchiolitis, babies may have difficulty feeding. Secretions block the nares, making breast and bottle feeding difficult. Babies may struggle to breathe and feed at the same time and can tire quickly (PCH 2020).

Symptoms typically last for 7 to 10 days, with peak severity at days 2 to 3. The cough may last for up to two to four weeks (SCHN 2021).

Assessing the Severity of Bronchiolitis

The following table can be used to assess the severity of symptoms of bronchiolitis. As a general rule, the more symptoms from the moderate or severe categories present, the higher the risk of developing severe illness (RCHM 2021).

Mild Moderate Severe
Behaviour Normal Some or intermittent irritability
  • Increasing irritability and/or lethargy
  • Fatigue
Respiratory rate Normal to mild tachypnoea Increased respiratory rate Noticeable increase or decrease in respiratory rate
Use of accessory muscles Nil to mild chest wall retraction
  • Moderate chest wall retractions
  • Suprasternal retraction
  • Nasal flaring
  • Noticeable chest wall retractions
  • Noticeable suprasternal retraction
  • Noticeable nasal flaring
Oxygen saturation/oxygen requirement Oxygen saturations >92% (in room air) Oxygen saturations 90–92% (in room air)
  • Oxygen saturations <90% (in room air)
  • Hypoxaemia that may not be corrected by oxygen
Apnoeic episodes None Brief apnoea Increasingly frequent or prolonged apnoea
Feeding Normal Difficulty with feeding or reduced feeding Reluctance or inability to feed

(Adapted from RCHM 2020)

Risk Factors for Bronchiolitis

The following risk factors increase the risk of severe illness from bronchiolitis:

  • Prematurity (born under 37 weeks gestation)
  • Being under 10 weeks of age
  • Postnatal tobacco exposure
  • Being breastfed for less than two months
  • Failure to thrive
  • Chronic lung disease
  • Congenital heart disease
  • Chronic neurological condition
  • Aboriginal or Torres Strait Islander ethnicity
  • Immunodeficiency
  • Trisomy 21 (Down syndrome)
  • Social factors such as remote geographical location or reduced access to transport.

(RCHM 2020; PCH 2021)

Infants with any of these risk factors may deteriorate rapidly. Therefore, admission to hospital should be considered even if the infant is initially presenting with mild symptoms (RCHM 2020).

Diagnosing Bronchiolitis

Bronchiolitis is usually diagnosed clinically, based on signs and symptoms. Most children don't require diagnostic investigations unless their condition is deteriorating, or there is diagnostic uncertainty (RCHM 2020).

Investigations such as chest x-rays, blood tests and virological testing are generally unhelpful (RCHM 2020).

Treating Bronchiolitis

Infants with mild symptoms can usually be treated at home. Management should include:

  • Avoiding smoking around the infant
  • Encouraging rest
  • Giving shorter, more frequent feeds to prevent dehydration and fatigue
  • Administering paracetamol to manage fever (always ensure you give the correct dose).

(SCHN 2021)

bronchiolitis sick infant with mother

If symptoms are more severe, the infant may need to be admitted to the hospital. Treatment is supportive, with oxygenation and intravenous fluids administered as required (RCHM 2020). Minimal handling in a calm, quiet environment has been a long-recommended strategy. The more the child becomes distressed, the more they experience respiratory problems.

Normal saline drops to the nares may help to loosen secretions to allow feeding. Nasal suctioning may be required in some cases but is not routinely recommended. Infants who have severe difficulty feeding may require nasogastric (NG) feeding. Frequent, small feeds are preferred (either oral or NG) (RCHM 2020).

Bronchiolitis is caused by a virus and therefore does not respond to antibiotics. Other medicines are not indicated in treatment either (RCHM 2020).

When to Escalate Care

Care should be escalated if the infant is displaying any of the following symptoms:

  • Wheezing or breathing difficulties
  • Rapid breathing
  • Eating less than half of their usual amount for at least two feeds
  • Dry nappy for 12 hours or longer
  • Sudden worsening of symptoms.

(Healthdirect 2020)

Signs of an emergency requiring immediate medical attention include:

  • Severe breathing difficulties or exhaustion from trying to breathe
  • Pale, sweaty skin or a blue tinge around the lips or fingernails
  • Very rapid breathing
  • Difficulty feeding
  • Extreme fatigue - inability to be roused or going back to sleep immediately after being woken.

(Healthdirect 2020)


Bronchiolitis is one of the leading causes of hospitalisation of children under 12 months of age. Knowing how to recognise the severity of the infection and manage its symptoms will help you to provide the best patient care, particularly in the winter months when the illness is most prevalent.


Test Your Knowledge

Question 1 of 3

True or false: Almost every child will experience respiratory syncytial virus infection before the age of two.


Abbie Blog View profile
Abbie is a Nurse Practitioner currently working in a Specialist Allergy Clinic in Brisbane. She has been a paediatric nurse for over 20 years originally working in the UK before moving to Australia with her young family 8 years ago. Abbie has a diverse career working with some of the most vulnerable patients. She has worked in paediatric oncology , emergency and general paediatrics. She has worked for NGO's in the fields of child protection and parental support as well as currently working with re- settled refugees. Abbie is a passionate nursing advocate and has just started the new challenge of blogging.
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