If you are a regular reader then you will know that I have been spruiking lung ultrasound for a few years now. In fact I wrote this post [ Ultrasound for pneumonia – sounds crazy? ] way back in early 2012. There continues to be a slow trickle of studies looking at US for pneumonia – and like a lot of US literature – the numbers are small in each paper.
In March 2015 Pediatrics published a systematic review titled:
Lung Ultrasound for the Diagnosis of Pneumonia in Children: A Meta-analysis by Perada et al. This was a metanalysis of 8 smaller studies (2 in neonates) which showed that lung US performed well as a diagnostic tool compared to CXR. The papers used a variety of “US users” from expert to novice sonographers.
The diagnostic characteristics have been reasonably variable across these small trials and they give the following as their overall analysis of lung US for pneumonia:
- Sensitivity 96%, Specificity 93%,
- + Likelihood ratio = 15.3 -ve Likelihood ratio = 0.06
- if you are into “area under the ROC” – it was 0.98 – which is pretty good!
These figures are our best estimate of the utility of LUS for pneumonia in kids. They are significantly better than the characterisitics of traditional plain film.
So, are we there yet? Is there enough evidence to change practice?
I think that there is.
Lung US is at least “non-inferior” to CXR. US carries no risk of radiation and is a fast and technically easy scan to do in small people. The cost is … a few dollops of gel and the time to do the scan.
There will certainly be a risk of overdiagnosis given the relatively high sensitivity of US and the potential to misinterpret findings. This is going to require education and training around image interpretation. As with all point-of-care US – one needs to interpret the images in the clinical context and be prepared to do another test if the data doesn’t make sense.
So I would love to hear your thoughts –
- is there enough here to change practice?
- what barriers are there in your practice to change imaging preferences?
Want to learn how to do this scan??
check this video tutorial from Sonokids / Kasia Hampton
My tips on technique:
- lots of data to get by looking at the bases: look for effusion, unilateral B lines,
- The middle lobes collapse to leave a wedge based laterally – this is high in the axilla in little kids – so you need to get up into the armpits to see this common site of consolidation.
- Anterior zones are easy to scan – zip down each midclavicular line
- Always correlate with you clinical findings. e.g.. if you think it is bronchiolitis clinically, and you see bilateral posterobasal, small sub-pleural consolidations – then it is bronchiolitis…. NOT bilateral pneumonia
- Keep using CXR and correlate until you are comfortable, but remember that 20 -30 % of sonographic pneumonias will be invisible on CXR [it is a more sensitive test]. So don’t be surprised if you get imaging that disagree
Let me know how you go.