Through the looking glass

Shares

As we head out winter in the southern hemisphere the northern hemisphere can see that ‘Winter is Coming’ and with it the scourge of the paediatric emergency departments – bronchiolitis.  It’s one of those diseases that the we should all be able to spot but the real challenge is picking up those that present as if they have bronchiolitis but in fact have a different disease entity altogether. 

Pneumonia may present clinically in a similar fashion to bronchiolitis. Radiographs inconsistent with the diagnosis are found in 7-23% of patients. Does that mean we should be doing chest x-ray on all children that present with bronchiolitis just in case?

Chao et al. tried to answer this question in the following paper –

Predictors of Airspace Disease on Chest X-Ray in Emergency Department Patients With Clinical Bronchiolitis: A Systematic Review and Meta-analysis

So what was they PICO that they subjected to systematic review and meta-analysis?

Population – Paediatric Emergency department patients under 2 years of age with a clinical diagnosis of bronchiolitis

Intervention – History and physical exam including vital signs

Comparator – A chest x-ray positive for airspace disease e.g. atelectasis, infiltrate or consolidation

Outcome – The sensitivity, specificity and likelihood ratios for finding a positive chest x-ray were calculated

It’s easy just to read the bottom line summary of an article but it’s worth getting used to reviewing papers critically and being skeptical of everything you see. Thanks to Ken Milne of the Skeptics Guide to Emergency Medicine for suggesting this tool.

How does the quality checklist for this systematic review pan out?

Is the question relevant? – Yes

Was the search for studies detailed and exhaustive? It seems to be and the full search strategy is listed in the article. The authors then tried to contact original study authors to obtain missing data.

Was the methodological quality of primary studies assessed for biases? The studies were assessed using a validated, diagnostic accuracy tool (QUADAS-2).  The paper includes a greta review of the potential biases of the original papers.

Were the assessments of studies reproducible? YesThere was a Cohen’s kappa value of 1 suggesting excellent inter-rater reliability.

Was there low heterogeneity for estimates of sensitivity/specificity? Yes.

Was the summary diagnostic accuracy sufficiently precise to improve on existing clinical decision making models? Yes, in that there are no specific clinical indicators that predict the presence of positive findings on a chest x-ray.

So the bottom line is that you should trust your instincts and not order chest x-rays on children with clinically obvious bronchiolitis. Not all that wheezes and crackles in infants is bronchiolitis however and if you suspect an alternative diagnosis such as congestive cardiac failure, pneumonia, pneumothorax or an inhaled foreign body* then go ahead and get some imaging.

What x-ray changes might you see in a case of bronchiolitis?

The majority of x-rays are normal.

Occasionally they may show bilateral, symmetrical hyperinflation with peri-bronchial cuffing and some atelectatic changes. Thanks to Radiopaedia for the image.

Case courtesy of Dr Luke Danaher, Radiopaedia.org. From the case rID: 16821

Case courtesy of Dr Luke Danaher, Radiopaedia.org. From the case rID: 16821

It’s an interesting paper to read but won’t actually change my management. Unless I have a high pre-test probability that a patient has a disease process going on other than bronchiolitis I am not likely to order a chest x-ray. I’m a big fan of using the ALARA (as low as reasonably acceptable) principle when it comes to imaging children and so might be more tempted to pick up the ultrasound probe than my pen to order a test. My go-to source for all things ultrasound and ‘out there’, Casey Parker, covers some of the literature here.

*A plain chest x-ray isn’t great at ruling out inhaled FB’s – that’s a post for another time.

References

Chao JH, Lin RC, Marneni S, Pandya S, Alhajri S, Sinert R. Predictors of Airspace Disease on Chest X‐Ray in Emergency Department Patients With Clinical Bronchiolitis: A Systematic Review and Meta‐analysis. Academic Emergency Medicine. 2016 Jul 1.

Schuh S, Lalani A, Allen U, Manson D, Babyn P, Stephens D, MacPhee S, Mokanski M, Khaikin S, Dick P. Evaluation of the utility of radiography in acute bronchiolitis. The Journal of pediatrics. 2007 Apr 30;150(4):429-33.

Basile V, Di Mauro A, Scalini E, Comes P, Lofù I, Mostert M, Tafuri S, Manzionna MM. Lung ultrasound: a useful tool in diagnosis and management of bronchiolitis. BMC pediatrics. 2015 May 21;15(1):1.

Zerella JT, Dimler M, McGill LC, Pippus KJ. Foreign body aspiration in children: value of radiography and complications of bronchoscopy. Journal of pediatric surgery. 1998 Nov 30;33(11):1651-4.

Print Friendly, PDF & Email

About 

An Emergency Physician with a special interest in education and lifelong learning. When not drinking coffee and reading Batman comics he is playing with his children.

@andrewjtagg | + Andrew Tagg | Andrew’s DFTB posts

Author: Andrew Tagg

An Emergency Physician with a special interest in education and lifelong learning. When not drinking coffee and reading Batman comics he is playing with his children.

@andrewjtagg | + Andrew Tagg | Andrew’s DFTB posts

One Response to "Through the looking glass"

  1. Henry Goldstein
    Henry Goldstein 1 year ago .Reply

    Really interesting paper Andy; I agree it’s not likely to change my thresholds for ordering a chest radiograph.

    In practice, I seem to see a significant number of patients with RSV-proven bronchiolitis whose radiographs demonstrate isolated (R) upper lobe collapse. This not infrequently leads to the initiation of antibiotics, much to the chagrin of my senior general paediatric colleagues.

    Fitzgerald and Kilham mention this in their 2004 review, but I can’t find much in the radiology/primary literature to confirm.

Leave a Reply