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Acute Bronchiolitis

Acute bronchiolitis refers to airway inflammation and obstruction of the lower respiratory tract and is caused almost exclusively by viral infection in children younger than 2 yrs
( Bronchiolitis Alyssa H Silver and Joanne M Nazif Pediatrics in Review November 2019 , 40 (11 ) 568-576 )


Occurs in children < 2 yrs and most commonly in 1st year of life Most common serious respiratory illness in infancy Peak between 3-6 months Symptoms peak between 3-5 days- then improve 90 % infnats will get better within 3 weeks Seasonal ↑↑ during winter and early spring ( N America and Europe ) Re-infection during a single season is possible

Diagnosing bronchiolitis-
Coryzal prodrome lasting 1-3 days followed by persistent cough and either tachypnoe or chest rececssion ( or both ) either wheeze or crackles on chest auscultation ( or both ) fever ( in around 30 % of cases usually < 39° ) high fever is uncommon ( ie > 39° ) poor feeding ( after 3-5 days of illness ) → rapid respiratory rate may not permit time for sucking and swallowing 

Young infants ( particularly < 6 weeks old ) may present with apnoe without other clinical signs

Signs of resp illness may include
 Tachypnoe Intercostal and/ or subcostal retractions Accessory muscle use Nasal flaring Grunting Colour change or apnoe Low O2 saturation Diagnosis is clinical
 based on hx and clinical findings

Breastfeeding reduces
 risk of RSV related admissions

 Smoking ↑ risk of admission

Examination-Oxygen saturation Hydration status ( CRT , Pulse rate, skin turgor etc ) Resp distress- RR , IC/SC recession , nasal flaring

Pathology-Viral illness ( Respiratory syncytial virus ) RSV is the pathogen in 70-80 % cases Other viruses including human metapneumovirus ( HMPV ) , influenza , rhinovirus , adenovirus and parainfluenza virus can all cause a similar clinical picture Transmission is by droplet and direct contact of respiratory secretions ( RSV ) or via enviornmental surfaces ( eg skin , clothes ) Mucous plugs obstruct bronchioles → can cause hyperinflation or collapse of the distal lung tissue Even small ↓ in diameter caused by inflammation and secretions → impairs laminar airflow leading to respiratory distress

Apnoe ( observed or reported ) Child looks seriously unwell Severe respiratory distress ( grunting , marked chest recession , RR > 70 ) Central cyanosis Sats persistently < 92 % on air- Admit emergency 999

RR > 60 /min Difficulty with breastfeeding or inadequate 
oral fluid intake (50-75 % of usual vol ) Clinical hydration- consider admission

Risk factors severe disease-Age < 12 weeks History of prematurity ( < 32 weeks ) Underlying cardiopulmonary disease Neuromuscular disorder Immunodeficiency

Suspected impending respiratory failure-Signs of exhaustion ( listlessness or ↓ resp effort ) Recurrent apnoe Failure to maintain adequate O2 saturation despite O2 supplementation

Differentials –Asthma Bacterial pneumonia GORD Congestive heart failure Vascular ring
Congenital defect causing airway/ oesophageal compression Croup Foreign body aspiration Pertussis Cystic fibrosis

NICE suggests to consider the diagnosis of a viral induced wheeze or early onset asthma in older infants and young children if they present with
◘ persistent wheeze without crackles OR
◘ recurrent episodic wheeze OR
◘ a personal or family h/o atopy
 Consider a diagnosis of pneumonia if
◘ high fever > 39° C
◘ persistently focal crackles

Bronchiolitis is a clinical diagnosis made on basis of history and clinical examination No investigations indicated in primary care other than oxygen saturation in children with mild bronchiolitis

In hospital-moderate and severe cases
 Lab tests may include CRP , FBC to exclude bacterial infection ,U-E ( if IV fluids needed ) Blood culture Isolating the virus – Nasopharyngeal aspirate
○ reduce antibiotic use
○ reduce number of investigations
○ shorten hospital stay CXR has not been shown to be helpful but usually done in moderate-severe cases Blood gas ( not routinely indicated )

Consider admission –child looks unwell respiratory rate of > 60 /min feeding difficulties
○ breastfeeding or
○ inadequate fluid intake ( 50 to 75 % of usual vol ) risk factors for developing severe bronchiolitis apnoea ( observed or reported ) persistent O2 level < 92 % central cyanosis inadequate fluid intake persistent severe resp distress take into account social circumstances

Management is supportive Aim is to maintain
○ adequate hydration
○ oxygenation ( cut-off for supplementation varies from 90-92 % ) Upper airway suctioning Observe for deterioration Current NICE guidance advice’s against using the following to treat bronchiolitis in children Ventilatory support in infants who are very unwell may involve
○ mask , high flow nasal cannula ( HNFC )
○ nasopharyngeal continous positive airway pressure ventilation or
○ endotracheal intubation Palivizumab humanized monclonal antibody 
( mAB) – expensive and requires several doses , its efficacy and cost effectiveness is not established and administration is cumbersome

Treatment not recommended- Antibiotics Hypertonic saline Adrenaline ( nebulised ) Salbutamol Montelukast Ipratropium bromide Systemic or inhaled corticosteroids A combination of systemic and nebulised adrenaline Antivirals

Supplemental Oxygen is a mainstay of
 treatment in hospital

Prognosis- From onset most
 infants would be asymptomatic 
by 2 weeks- a small proportion will still 
have symptoms 
after 4 weeks

Complications –Respiratory ( e.g apnoea , respiratory failure Bacterial
otitis media
UTI ( rare ) Death
rare in the developed world

safety-netting –Recognise red flag symptoms

○ worsening work of breathing ( eg grunting , nasal flaring , marked chest recession )
○ fluid intake is 50-75 % of normal or no wet nappy for 12 hrs
○ apnoe or cyanosis
○ exhaustion ( for eg not responding normally to social cues , wakes only with prolonged stimulation )
 Not to smoke in child’s home ( symptoms can get ↑ severe ) How to get immediate help


Parent information printable from Oxford Clinical Commissioning Group

Paediatric Normal Parameters from University of Iowa Healthcare

NICE Guideline on Bronchiolitis
NICE Traffic Light system for identifying risk of serious illness



  1. Acute Bronchiolitis Gatechew Teshome et al Pediatr Clin N Am 60 ( 2013 ) 1019-1034
  2. Bronchiolitis in children: diagnosis and management NICE guideline June 2015 National Collaborating Centre for Women’s and Children’s Health (UK).
  3. Bronchiolitis: Diagnosis and Management of Bronchiolitis in Children. London: National Institute for Health and Care Excellence (UK); 2015 Jun. (NICE Guideline, No. 9.) 3,
  4. Diagnosis and assessment of bronchiolitis. Available from:
  5. Management of bronchiolitis in infants: key clinical questions McNaughten, Ben et al Paediatrics and Child Health, Volume 27 , Issue 7 , 324-327
  6. Acute bronchiolitis in infants , a review Knut Øymar et al Scand J Trauma Resusc Emerg Med. 2014 : 22:23 Justice NA, Le JK.
  7. Bronchiolitis. [Updated 2019 Feb 23]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2019 Jan-. Available from:
  8. Bronchiolitis: Assessment and evidence-based management by Dominic A Fitzgerald and Henry Kilham The Medical Journal of Australia May 2004 Caballero MT, Polack FP, Stein RT.
  9. Viral bronchiolitis in young infants: new perspectives for management and treatment. J Pediatr ( Rio J ). 2017; 93:75-83


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