According to the AAP’s 2006 Clinical Practice Guideline, bronchiolitis is the most common lower respiratory tract infection (LRTI) in infants and is caused by a virus – most often RSV in 70-80%, Human metapneumovirus in 10-20%, and then assorted rogues such as Adenovirus, Rhinovirus, Parainfluenza, and Influenza pulling up the rear. Its cardinal pathophysiologic features include;

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  • Acute inflammation
  • Edema and necrosis of epithelial cells lining small airways
  • Increased mucous production
  • Bronchospasm
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It is rare in the first month of life, and peaks between ages 2-5 months – with 90% of children having some sort of RSV infection in the first 2 years of life. Most cases are seen between December and March. The symptoms include those of both upper and lower respiratory tract infections.

URI Symptoms

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  • Rhinitis[/list]

LRTI Symptoms

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  • Tachypnea
  • Cough
  • Wheezing
  • Crackles
  • Accessory muscle use
  • Nasal flaring
  • Fever in only 30%

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Bronchiolitis Course

In general the clinical severity of symptoms peak between the 4th through the 6th day. Though Human metapneumovirus may see a later peak than RSV by a day or two.

The annual cost of hospitalizations is estimated at $700 million dollars.

Interestingly the rate of inpatient stays has increased since the development of pulse oximetry – Hmmm .

 

Stay tuned to this site for a series of posts exploring various diagnostic and therapeutic options for bronchiolitis – In total I hope that this will be a ‘mini-elective’ in managing this persistent illness.

Special thanks to my colleague, and local bronchiolitis aficionado Todd Florin, MD, MSCE.