A 4 month-old male presents with a 3 day history of low grade fever and runny nose.  He has now developed a cough and has some trouble breathing at times.  His immunizations are up to date, and he is an only child.  He has no known sick contacts, but he attends day care.  On physical exam, his axillary temperature is 38.1 degrees Celsius, his respiratory rate is 50 per minute, he coughs frequently, and he looks quite ill.  He has diffuse expiratory wheezes and mild rhinorrhea.  The remainder of his physical exam is normal.



Bronchiolitis is usually seen in children less than 2 years old, and the highest incidence is seen in infants less than 6 months old.  It is a seasonal disease, with outbreaks frequently seen during the winter months.  The vast majority of cases are caused by Respiratory Syncytial Virus (RSV) infections, with parainfluenza virus, adenovirus, human metapneumovirus, coronavirus, Bocavirus, human parechovirus, and Mycoplasma as other known, but less frequent, causes.  These infections cause increased airway resistance, coughing, and wheezing secondary to increased bronchiole edema and mucus production.  The disease is most severe in children with congenital heart disease, bronchopulmonary dysplasia (BPD), or prematurity.




  • History of URI symptoms
  • Cough
  • Decreased feeding
  • Respiratory distress (presents day 3-5 of illness)


Physical exam findings

  • Low grade temperature
  • Tachypnea and respiratory distress
  • Wheezing
  • Rales
  • Dehydration
  • Hypoxia



  • Clinical diagnosis; common in December-April months
  • Can be confirmed with ELISA or DFA of nasal washings of culture, and these tests have excellent sensitivity and specificity
  • Chest X-ray can show peribronchial cuffing, air trapping, flattened diaphragms, and areas of atelectasis

X-ray of a child with RSV bronchiolitis showing the typical bilateral perihilar fullness



  • Supplemental oxygen as needed
  • Maintenance fluids or normal saline if PO intake is poor
  • +/- bronchodilators (have not been proven to be effective); can try once, but if not effective, should be discontinued
  • No role for antibiotics or corticosteroids
  • Palivizumab is a monoclonal antibody that is given monthly during the RSV season.

AAP Recommendations for use of Palivizumab - click here


Indications for admission

  • Hypoxemia
  • Underlying BPD, cardiovascular condition, or immunologic deficiency
  • Dehydration and poor PO intake
  • Parental anxiety or poor follow-up


Hospital course

  • Often, patients will appear very toxic and will need careful observation with continuous pulse oximetry monitoring and oxygen supplementation
  • There is generally quick spontaneous improvement within 48 hours of admission
  • Mortality is very rare and almost exclusively associated with underlying conditions
  • 1% of patients developed secondary bacterial pneumonia 



  • Hand to hand, respiratory droplets, conjunctival transmission
  • Patients should be on strict contact isolation
  • 5-8 day incubation period with viral shedding of 3-4 days



Bronchiolitis versus asthma

  • Age of patient (younger favoring bronchiolitis)
  • Time of year
  • Prodrome of URI symptoms
  • Family history of asthma/atopy
  • Response to bronchodilators



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  2. Perlstein P. Evaluation of an Evidence-based Guideline for Bronchiolitis. Pediatirics. 1999
  3. Garrison M.M. et al. Systemic Corticosteroids in Infant Bronchiolitis: A Meta-analysis. Pediatrics. 2000
  4. Breese H. C. Respiratory Syncytial Virus and Parainfluenza Virus.  NEJM June 2001
  5. Titus M.O. and Wright S.W. Evaluation of Infants with Fever and Respiratory Syncitial Virus Pediatrics August 2003
  6. Wohl M.B. Treatment of Acute Bronchiolitis NEJM 2003
  7. King V.J. et al. Pharmacologic treatment of bronchiolitis in infants and children.  A systemic review.  Arch Pediatr Adolesc Med 2004
  8. Bordley W.C. et al. Diagnosis and testing in brondhiolitis.  A systemic review. Arch Pediatr Adolesc Med. 2004
  9. Subcommittee on Diagnosis and Management of Bronchiolitis. Diagnosis and Management of Bronciolitis Pediatrics 2006
  10. Smyth R. Openshaw P. Bronchiolitis.  Lancet 2006 
  11. AAP.  Modified Recommendations for Use of Palivizumab for Prevention of Respiratory Syncitial Virus Infections.  Pediatrics Dec 2009
  12. Zorc J. and Breese Hall C. Bronchiolitis: Recent Evidence on Diagnosis and Management.  Pediatrics Feb 2010