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;
- Acute inflammation
- Edema and necrosis of epithelial cells lining small airways
- Increased mucous production
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.
- Accessory muscle use
- Nasal flaring
- Fever in only 30%
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.