Tag Archives: bronchiolitis

Probing Questions: Lung Ultrasound in Diagnosis and Management of Bronchiolitis

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Thanks to Casey Parker of Broomedocs for this guest contribution – his review is cross-posted here.

Where can I find this paper?


What is this paper about (what is the research question)?

This paper aimed to correlate sonographic lung findings with clinically diagnosed bronchiolitis in infants.  The authors also attempted to provide some prognostic information [the need for oxygen support] based on sonographic lung features.

Summary of the Paper

The subjects were infants admitted for clinically suspected bronchiolitis.  There was also a cohort of “normal controls” used as a comparison.  The children underwent a clinical scoring by the treating Paediatrician and lung ultrasound by both a radiologist and Paediatrician sonographer.  The scans were all completed by two of the authors.

Design: Single-centre, observational cohort study conducted in an Italian Paediatric unit.

Objective: to evaluate the accuracy of lung ultrasonography in the diagnosis and management of bronchiolitis in infants.

Outcome of interest:  correlation between clinical and sonographic lung findings in bronchiolitic infants.  Can LUS findings be used to predict the need for supplemental oxygen requirements?

Participants: One hundred six infants, aged from 9 to 239 days old were enrolled.

  • Inclusions: clinically “suspected bronchiolitis” in infants.  Unclear as to whether these were consecutive cases – only 106 over a 3 year study period.
  • Exclusions: radiological pneumonia, other “concomitant pathology” or the unavailability of the study sonographer.

Results: There was a high level [ ~90%] of agreement between the clinician’s severity rating and the predetermined sonographic severity scores.  There was also a high level of agreement between the two sonographers scoring of the LUS findings (K = 89.6%).  The lung US scoring predicted the need for oxygen supplementation with good accuracy [sensitivity: 96.6 %, specificity 98.7 % ] although there were wide confidence intervals as a result of the small numbers in this trial.

Authors’ Conclusions:

In summary, this pilot study demonstrates that the use of LUS in bronchiolitis can be considered as an extension of the clinical evaluation and could be incorporated into clinical algorithms to aid decision-making. Our promising data needs to be confirmed in larger cohort studies also involving critical patients.

On the study design

 This study design is typical of many pilot ultrasound papers.  Small numbers of patients in which sonography is compared to a gold-standard that may not be entirely accurate of itself.  Bronchiolitis is a clinical diagnosis, with no really objective diagnostic standard.  The use of just 2 experienced Paediatric sonographers in a single centre does raise questions about the external validity of the results and there is a high likelihood of bias here.  The clinicians were blinded to the sonographic findings – and therefore the risk of bias here was removed.  The use of “normal cohort” and the “RSV swabs” in the study design was a little confusing and doesn’t really add to the results.

What were the results and what does this mean?

The results suggest that clinically diagnosed bronchiolitis looks like…. sonographic bronchiolitis as per the defined criteria used in this paper.  The protocol used did identify infants with more severe lung disease.  The need for supplemental oxygen was consistent with more severe LUS changes.  However, given the “standard” was clinical examination it is unclear exactly what LUS would add to the prognostication by paediatricians.  The high degree of agreement between the two study sonographers is difficult to extrapolate given they are both highly skilled, ultrasound enthusiasts – a larger mix of observers would be needed to draw any conclusions about our ability to utilise LUS in small kids.

What can we take from this paper into clinical practice?

Lung ultrasound for the diagnosis and severity scoring of bronchiolitis is reasonably accurate.  Does it add anything?  Probably not, unless you are currently using CXR to ‘diagnose’ bronchiolitis.  This paper does provide some useful descriptions of the spectrum of disease and their sonographic appearance.

I think this paper is interesting in that it describes the sonographic spectrum of a common disease of infants.  The study is not really large enough, nor does it have the external validity to make it a “practice changer”.   This pilot can help inform us about the appearance of bronchiolitis – and in the future this may become a more commonplace part of our clinical assessment of children – but for now I am not sure it adds to our quiver.

More questions to ask

  • Can ultrasound reliably differentiate bronchiolitis from important differential diagnoses in infants ? (e.g.. pneumonia, heart failure, upper airway obstruction… )
  • Are the sonographic findings in bronchiolitis consistent when obtained by sonographers of various experience?
  • Previous papers have compared LUS to conventional CXR for the diagnosis of bronchiolitis – and LUS was favourable.  It would be nice to see a paper looking at children with severe disease in which clinicians often turn to CXR to “reconfirm the working diagnosis” in order to ascertain its utility at that end of the spectrum.

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Oxygen Saturation Targets in Bronchiolitis – Magic Numbers?

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Where can I find this paper?

http://www.ncbi.nlm.nih.gov/pubmed/26382998 – this paper is currently open access

What is this paper about (what is the research question)?

Is a target oxygen saturation of 90% or higher equivalent to 94% or higher for resolution of illness in acute viral bronchiolitis?

Summary of the Paper

Design: multicentre, parallel group, randomised controlled equivalence trial with allocation concealment.

Objective: to determine whether accepting a reduced lower limit target oxygen saturation in infants with viral bronchiolitis affected time to resolution of illness

Primary outcome measure: time to resolution of cough (parental reporting)

Intervention: subjects were randomised following decision to admit, to either standard SpO2 monitoring or a modified oximeter which skewed the reading such that SpO2 90% read as 94%. All other care was standard.

Participants: 615 subjects randomised between 03/10/2011-30/03/2012 and 01/10/2012-29/03/2013. 308 randomised to standard group, 307 to modified oximeter group

  • Inclusions: infants aged 6 weeks to 12 months (corrected gestational age) with clinically diagnosed bronchiolitis admitted to hospital for supportive care following presentation to the Emergency Department or Acute Assessment Area
  • Exclusions: preterm (<37 weeks) who had received oxygen in past 4 weeks; cyanotic or haemodynamically significant heart disease; CF or interstitial lung disease; documented immunodeficiency; direct admission to HDU/ICU; previously randomised

Results: Median time to cough resolution was 15.0 days in both groups with a median difference of 1.0 days (95% CI -1 to 2). This fell between the prespecified equivalence limits of plus and minus two days.


Authors’  conclusions

In children with acute viral bronchiolitis, the time taken for symptoms to resolve was the same whether they were managed to a target oxygen saturation of 90% or 94%.

On the study design


This study used eight centres to recruit a sample with 80% power to detect non-equivalence of greater than two days in time to resolution of cough. Cough resolution was determined by parents at pre-determined follow-up phonecalls (7, 14, 28 days and 6 months). Some allowances were made for inaccurate recording of this data using random selection of a date between the last time the cough was known to be present and the first date it was noted to be absent (if available). This method of reporting does still leave the outcome open to some parental bias and accuracy of reporting cannot be guaranteed.

Allocation to a group was concealed until definite enrolment, and the allocation was masked to study staff, hospital staff and parents. It’s not clear why the authors have chosen to use the work “masking” rather than “blinding”.

Several interesting secondary outcomes were also recorded although it is always worth remembering that studies are designed and powered to detect differences in the primary outcome and may be underpowered to detect differences in secondary outcome. The authors decided in advance to statistically analyse time until “fit for discharge” and actual discharge date for both groups, along with parental anxiety scores and whether the child was fit to attend daycare.

What were the results and what does this mean?


Following some loss to follow-up and protocol violations, 293 subjects were analysed in the standard group at 6 months and 291 in the modified oximeter group. This still reflects a study population greater than that determined by the power calculation. There was no difference in the median time to cough resolution which was 15.0 days in both groups.

The authors addressed both intention to treat analysis (analysing those subjects with protocol violations – being given the wrong oximeter probe – according to their original allocated group) and per-protocol analysis (analysing them only if they fulfilled the allocation from start to finish) and found this did not affect the results.

The modified group also had quicker return to adequate feeding and “back to normal” time. Patients in the modified group, predictably, received supplemental oxygen in fewer cases, for a shorter period, were considered fit for discharge sooner and were discharged sooner. There were fewer serious adverse events and adverse events in the modified group (35 SAEs in 32 infants in the standard group vs 25 SAEs in 24 infants in the modified group). The modified group had increased HDU admissions (13 episodes in the modified group vs 8 in the standard group) but fewer reattendances (26 in the standard group vs 12 in the modified group).

The authors postulate that having a higher target oxygen saturation influences decisions about fitness for discharge and that the increased use of oxygen in the standard group might have adversely affected feeding through drying of nasal passages, reflected in the time to adequate feeding. They also suggest that increased time in hospital in the standard group might expose these infants to nosocomial infection, causing the increased readmission rate – but of course this is all speculation 🙂

What can we take from this paper into clinical practice?

It seems that infants subjectively recover from bronchiolitis at the same rate even if we target SpO2 90% or above instead of 94% or above. However this was a population for whom a need for admission to hospital had already been identified and the extrapolation of this to the Emergency Department population is not wholly appropriate. We can be reasonably relaxed about SpO2 90-94% in these patients but until further work is done to reflect our undifferentiated population we should probably be careful about assuming we can safely discharge these infants.

More questions to ask

  • Would we see the same resolution and patterns of return to normal behaviour/complications in the undifferentiated ED population of infants with bronchiolitis?

See Also:

Don’t Forget the Bubbles – Tessa Davis reviews a JAMA paper on oxygen saturations in admission decision-making in patients with bronchiolitis – http://dontforgetthebubbles.com/effect-oximetry-hospital-admission-bronchiolitis/


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