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Ultrasound for pneumonia – sounds crazy?

You may have noticed my recent obsession with all things respiratory.  Seeing and personally experiencing a lot of LRTIs recently. 

A few weeks back Cliff Reid @resus.me put up this article for discussion: Lung US for pneumonia in ED, Emerg Med Journ 2012.  Which suggests that US is at least as good as an CXR for the early diagnosis of pneumonia and actually picked a few more when the CTs were compared as a gold standard.  It was a small study of 120 patients – so I thought I would look further into the literature – see what else is out there.  Here is what I found:

Evaluation of lung ultrasound for the diagnosis of pneumonia in the ED. Amer Journ Emerg Med 2009

Ultrasound diagnosis of pneumonia in children.  Radiol Med. 2008

Clinical application of transthoracic ultrasonography in inpatients with pneumonia.  Europ Journ Clinical Investigation 2011.

Diagnosis of radio-occult pulmonary conditions by real-time chest ultrasonography in patients with pleuritic pain.  Ultrasound in Med Biol 2008

It seems the Italian sonographic community have cornered the market in all things chest US in the past few years!

So in summary if you are too busy to read the articles – there are a pile of little observational studies out there that all say the same thing – US is as good as a CXR, maybe a little more sensitive for showing pneumonia / consolidation.  It is very likley to be better than the clinical examination – however that is not how this works. 

If you hear something or are unsure – then use the probe as the next “test” – if you get a positive then likley you have found a pneumonic process.  You can treat this as clinically appropriate, and still get a CXR if necessary later.  However, especially in kids – do you really need to irradiate them?  Or can we use clinical progress, repeat US and still achieve the same ends?

I suspect those of us who grew up on CXR diagnosis will be more comfortable seeing a positive, or a negative – however if you look in the numbers – CXR has a significant false negative rate in pneumonia (especially early in the disease) – so should we be so comfortable?  I think this is one of those common biases in Medicine – we attribute too much weight to a familiar test, even though we know it might be steering us in the wrong direction.  We like yes/no, black/white answers – and believe in CXR as it has been drilled into us from day 1 of Med School!

This is a great example of US being an “extension of the clinical examination” rather than a “test” – after all, with US you are looking at the sound that you might be able to hear with your stethoscope and ears.  I suspect in 10 years this will be something we teach in Medical Schools – the old look, listen, feel, percuss with have “scan” added to the end of the exam.

Love to hear your thoughts

Casey

Comments

  1. Exactly.

    I’m using USS more and more – the problem of course is getting enough ‘numbers’ and being sure that I am scanning correctly…the short day courses for rural docs don;t cut the mustard.

    Wonder if it’s worth compiling a list of worthy USS uses for the rural doc – eFAST, RUSH, PTX, Symphysis pubis (pelvic fracture), long bone fracture, RO/RI pneumonia, optic nerve etc.

    Particularly interested in which ARE the useful tests for the “occasional sonographer” and developing some protocols/templates for wider dissemination.

    tim

  2. I personally haven’t use US for pneumonia, and I would probably have to do a fair number of ‘internal validation’ using a CXR for QA before I’d be comfortable actually using it diagnostically. I feel like the diagnostic criteria these guys use for PNA might be a little difficult for the average doc to use accurately.

    I have used lung US for diagnosing pulmonary edema though, and find it quite simple and useful in this case, as well as being faster than CXR.

  3. toby thomas says

    A simple but surprisingly accurate protovol for scanning the chest is described in “The Rapid Assessment of Dyspnea with Ultrasound: RADiUS” by William Manson and Nadim Hafez in Ultrasound Clin 6 (2011) 261–276. We have used the same protocol for a couple of years (but sadly were too lazy to publish it) and have achieved sens and spec for CCF and pneumonia of over 90%. You can scan a patient in the resus bay and get a diagnosis within minutes (ie long before you can get an xray)

    Also, whilst the Italians are doing some amazing stuff we should give credit where it is due. Without the pioneering and ongoing work of Daniel Lichtenstein no one would be doing lung ultrasound. He is to ultrasound what Jimmy Hendrix was to the electric guitar (No Hendrix, no Clapton. No Clapton, no Van Halen. No Van Halen, no Steve Morse. You get the picture)

  4. Mattia Quarta says

    Maybe the enduring aura of the stethoscope has stood in the way of its decline. Ironically this iconic tool that revolutionized clinical practice had ferocious detractors at its beginnings and Laennec was ridiculed for his invention. I was absently considering this idea last night when discharging a patient that I had diagnosed with a community acquired pneumonia. The clinical picture was suggestive and it took me few minutes to confirm my suspicion with a chest ultrasound. it was less obvious to spare him x rays since this is the conventional standard. Yet the ED was dramatically overcrowded and there was no good reason to add another febrile patient to the queue toward radiology nor to radiate him in the first place. So I just wrote down a brief ultrasound report and sent him home. It’s been ten years now that I use sonography in my daily clinical practice. I work in an Italian ED and we guys are quite maniac over ultrasound (it appears less on other sound propagations techniques such as navigation sonars!). Yet the more I ponder on how much sonography has substantially changed my approach to the patient the more I realize that I haven’t drawn ultimate conclusions from it. We should steadily integrate ultrasound in our diagnostic algorithms and accordingly change our logistics and professional habits. Great intriguing blog!

  5. Casey Parker says

    Great comments. Thanks for the corrections
    Tim – the way I think we get experience is by scanning a lot of ptatients and correlating with our current tools – stethoscope / X-ray

    I recall feeling incompetent for at least 2 years when I started using a stethoscope – we have to reschool ourselves. It will take time , errors are how we learn. So now I try and scan as many pts as I can. I guess that is why it is called ” clinical practice ”
    Casey

  6. minh le cong says

    thanks Casey
    great post and really appreciate you highlighting this area pf USS application. In remote Australia, getting CXRs is not always simple. I recall doing the basic radiography licensing course with Tim..many years ago in Adelaide , so we rural doctors could take our own plain films. I am average at best with plain film taking. but USS should be the next stage of your physical exam

  7. toby thomas says

    The latest issue of EM Critical Care is entitled “Emergency Ultrasound In Patients With Respiratory Distress”. It is well worth a read.

  8. Ah, if only I had access to online journals. Anyone (ahem) wanna send me a PDF?

    Minh, didn’t realise we’d done that xray course together! Seems a long time ago…

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