The college loves bronchiolitis. Of the four questions in the past papers, three were unequivocally about bronchiolitis (eg. "A 12-month-old infant is admitted to your ICU with bronchiolitis"). The other SAQ had a patient with bronchiolitis, but the discussion strayed into the wider territory of respiratory failure. Bronchiolitis has therefore featured in 20% of the past paper paeds questions (because there haven't been that many paediatric SAQs -understandably, in this adult intensive care exam). It is therefore an important topic to revise in the pre-dawn panic of Day 0.
For background reading, one may pay for the UpToDate articles on bronchiolitis, or read the free "Clinical practice guideline: the diagnosis, management, and prevention of bronchiolitis" from the American Academy of Pediatrics. Both sources were used in the making of this summary.
To call it "bronchiolitis", your infant needs to have the following features:
Histologically, there is acute inflammation, edema, and necrosis of epithelial cells lining small airways, and increased mucus production. Wheeze is an important clinical feature but overlaps with asthma and "recurrent virus-induced wheezing" which is apparently a serious paediatric diagnosis. For the purposes of bronchiolitis reasearch, you've got to do better than that. Researchers have developed a series of more functional definitions. For instance, in the study by Plint et al (2009) which investigated the benefits of dexamethasone, bronchiolitis was defined as "the first episode of wheezing associated with signs of an upper respiratory tract infection during the peak RSV season".
RSV is in fact the most common pathogen. Other possibilities include rhinovirus, influenza, parainfluenza, human metapneumovirus, human bocavirus, adenovirus and coronavirus (which could extend towards SARS and MERS).
Question 11 from the first paper of 2016 asked for five differential diagnoses. The whole table of differentials for respiratory failure in children was reproduced in the discussion section. However, there are specific broncholitis mimics which need to be mentioned, as they also present with wheeze.
Radiographic features are also discussed in the literature, and they consist of hyperinflation and peribronchial thickening. Classically, there shouldn't be consolidation. Classically, there should also be no chest Xray, as the AAP recommends against it.
Question 11 from the first paper of 2016 asked for four such features. The college listed a total of seven - eight if you include tachypnoea. They were as follows:
Unsurprisingly, there are more formal way of looking at the severity of bronchiolitis. For example, in the study by Plint et al (2009) observers used the Respiratory Distress Assessment Instrument (RDAI) which was developed by Lowell et al in 1987 to measure the effects of nebulised adrenaline on bronchiolitic infants. Unfortunately all these tools are completely useless because the level of respiratory distress in infants varies from minute to minute (depending on the frequency and efficacy of hugs, etc) and so any given RDAI value becomes completely useless almost as soon as it is recorded.
The following list is a mixture of the Question 11 from the first paper of 2016, UpToDate and the AAP guideline.
This section is constructed in a manner which also answers the "assessment" components of Question 6 from the first paper of 2009 and Question 28 from the first paper of 2008.
The management section here will discuss "ICUable" bronchiolitis, rather than the mild disease which is managed with "continue feeding, comfort" (the college model answer from Question 11 from the first paper of 2016). Severe bronchiolitis management can be described in the followign manner:
Plint, Amy C., et al. "Epinephrine and dexamethasone in children with bronchiolitis." New England Journal of Medicine 360.20 (2009): 2079-2089.
Lowell, Darcy I., et al. "Wheezing in infants: the response to epinephrine." Pediatrics 79.6 (1987): 939-945.
Ralston, S. L., A. S. Lieberthal, and H. C. Meissner. American Academy of Pediatrics Subcommittee on Diagnosis and Management of Bronchiolitis. "Clinical practice guideline: the diagnosis, management, and prevention of bronchiolitis". Pediatrics 134.5 (2014): e1474-e1502.
Osvald, Emma Caffrey, and Jane R. Clarke. "NICE clinical guideline: bronchiolitis in children." Archives of disease in childhood-Education & practice edition (2015): edpract-2015.
Alansari, Khalid, et al. "Caffeine for the Treatment of Apnea in Bronchiolitis: A Randomized Trial." The Journal of pediatrics (2016).