Lung POCUS and the zone wars

Probe positioning is very well defined for echocardiograpy, FAST and vascular scanning.  However with the thorax there is a lot of real estate, and a lot of lung.  Is there  an agreed plan and language for scanning the lungs?

First a surface anatomy refresher:

09fig_lunglobes
from http://imbus.anwresidency.com/txtbook/03_lung.html

For lung ultrasound assessment for assessment of interstial oedema there seems to be two  main methods, following Volpicelli (Italy)or Lichenstein (France).  Great slides by Lichenstein here.

First I present the 4 lung zones for each hemithorax described by Volpicelli from 2006:

zones_volpicelli
from https://www.youtube.com/watch?v=VzgX9ihnmec

With two zones anteriorly and two under inferior to the axilla.  Different articles seem to variously place the horizontal line at the 3rd or 5th intercostal space.

And the three zones of Lichenstein and the BLUE (Bedside Lung Ultrasound In Emergency) protocol (really six as they divide the three zones into upper and lower, without setting out anatomical borders for upper/lower) from 2008.

lungpocuszoneslichenstein
https://com-anest.sites.medinfo.ufl.edu/files/2015/11/The-Blue-Protocol.pdf

In 2008 there were also two of the Italian workers Copetti & Cattarossi who described POCUS zones for paediatric lung infections were “The probe was placed perpendicular, oblique and parallel to the ribs in the anterior, lateral and posterior (lower and upper) thorax.”, creating six zones on each hemithorax, they don’t provide any guiding images.

Then there are various EM/ICU/CC/Anaesthesia protocols eFAST, RUSH, CCUS,FATE, F-LUS:

m_chest_148_4_912_fig01
CCUS – Critical Care Ultrasound, similar to Volpicelli, adds a 5th zone for dependent pleural fluid (PLAPS -Postero-Lateral Alveolar Pleural Syndrome- see also BLUE protocol) http://journal.publications.chestnet.org/article.aspx?articleid=2297756
efast
eFAST – extended Focused Assessment with Sonography in Trauma – adds two anterior high thoracic and two low lateral thoracic probe positions to the FAST scan
RUSH - Rapid Ultrasound for Shock and Hypotension, two anterior thoracic windows http://sinaiem.us/tutorials/rush/
RUSH – Rapid Ultrasound for Shock and Hypotension, two anterior thoracic windows
http://sinaiem.us/tutorials/rush/
lung portion of FATE (Focus Assessed Transthoracic Echo)
lung portion of FATE (Focus Assessed Transthoracic Echo)
m_chest_144_6_1868_fig01
F-LUS – expansion of FATE( Focused Lung Ultrasound/Focus Assessed Transthoracic Echocardiography) which the authors state is a modification of Lichenstein and Volpicelli http://journal.publications.chestnet.org/article.aspx?articleid=1728827

If you want to really wig out there is a 28 zone protocol to use:

http://handsonecho.com/sites/53072f21c97d797504000002/content_entry530f3ce3c97d79b7c2000279/5470daaac97d7945d40d6b5f/files/How_I_do_it.pdf
http://handsonecho.com/sites/53072f21c97d797504000002/content_entry530f3ce3c97d79b7c2000279/5470daaac97d7945d40d6b5f/files/How_I_do_it.pdf

 

I really just like this pragmatic approach:

wheretoputtheprobe
http://handsonecho.com/sites/53072f21c97d797504000002/content_entry530f3ce3c97d79b7c2000279/5470d878c97d7904e30d4f41/files/Semiotics_A.pdf

What will I be using in general practice? As per my positioning post, clothing access and patient positioning and room ergonomics play a large part of the scanning process for me.  The questions I want to address pneumothorax yes/no, B-lines/interstial oedema yes/no, consolidation yes/no and effusion yes/no would be well answered by any of these however the CCUS five zones (1R, 2R, 3R, 4R, 5R) modification of Volpicelli’s zones seems clear and allow me to have a re-producible note for myself in the patient record and onscreen comments for review scans. For on-referred patients (usually going to the ED for LRTI) I will still use word descriptors because we do not yet have a lingua franca for lung ultrasound zones.

I have not talked about probe selection or probe orientation (mostly perpendicular to ribs to achieve the Bat Wing sign, the FATE low pleural views are parallel to ribs to view lung/diaphragm/liver or spleen) or lung scoring systems.

Another learning point from my reading around these zones was something I have not been doing – scan low on the back to get kidney and then work up when patient is sitting. You will ensure you are low, below diaphragm and as you scan up in area 5R you give yourself the best chance of spotting the curtain sign of the diaphragm and then a dependent effusion.

 

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Patient positioning and GPPOCUS

Traditional sonography has the patient on a examination couch, usually in the centre of the room with machine on the patients right.  POCUS in the ED can replicate this, or for procedures have the screen on the patients left, operator on the patients right however access around the patient on the hospital trolley bed is preserved.

In general practice we are often more constrained. Rooms can be small, beds are often fixed or too heavy to move easily and if not electric can be hard/unsafe for the elderly to climb.

Time constraints of a consultation also come into play – it can take a very long time for someone in winter layers to take everything off, lie down on the examination couch and then dress again.

So for pure reasons of anatomical access, safety, timeliness and privacy there are some scans that just need to go to the formal sonographer due to pure patient positioning reasons.

I have also been using a sitting position for lung POCUS, the patient sitting sideways on a chair without arms, allowing access to the back and infra-axillary lung windows.  This however must affect rib spacing and ?increased lower zone consolidation compared to the ideal lying down with hands behind head in a trolley. Some articles do suggest a lying or sitting position equally valid and points out that sitting is preferred for the very dyspnoeic. This is another article from a early researcher/adopter of LungPOCUS, Volpicelli, who states there is no difference in lying/sitting/standing as fluid shifts occur slowly in the lungs.

Home Visit POCUS

 

homevisitclean

For the elderly infirm, getting to the practice and then on to pathology/radiology can be a real expedition for the patient and the family. GP’s are perfectly poised to be doing this for the select patient.
Was the SOB COPD or CCF? a quick look with the US confirmed the clinical suspicions with oedema in Zones 2 left, Blines (lung rockets)

homevistleftzone2

and Zone 3 left:

homevisitleftzone3

Similar picture on the right, so fitting more with a picture of mild interstitial oedema than COPD and ACEI/Beta Blocker directed therapies.

(patient consent for image and photograph use was obtained)

Two GP related POCUS articles – Canada & UK

Quite an in-depth review article that looks at the varied usages for ultrasound in the general practice setting from the Journal of Family Practice, CanadaJournalFamilyPractice

Over five pages the article covers AAA screening, obstetric dating, guiding procedures, quick look cardiac assessment.  The article also provides a good precis of relevant evidence for non-sonographer/radiologist ultrasound use.

 

Next is a research study from the British Journal of Cardiology. To be clear the person doing the scanning was not a general practitioner, they were a trained sonographer however the setting was in general practice – assessing what findings a quick look cardiac scan can detect.

BritJournalCardiology

Of 163 scans, they were normal in 80 (49%), mildly abnormal in 67 (41%) and significantly abnormal in 16 (10%).

stethoscope or dermatoscope?

 

dermatoscope

When attempting to describe the utility of POCUS, the use of US has been described as the stethoscope of the future and that the stethoscope, born with René Laennec 200 years ago in 1816 was dead.

However I posit that within the Australian general practice setting, the dermatoscope is the better comparison. The dermatoscope aids in treatment by improving accuracy of diagnosis, allowing benign skin lesions to remain and confirming concerns about suspicious lesions.

  • Using the dermatoscope well is a skill that benefits the patient with less benign lesions removed through better accuracy in diagnosis
  • The clinician benefits from extension of diagnostic skills and satisfaction gained from assisting the patient
  • The dermatoscope is not required for GP clinic accreditation, unlike some other clinic equipment (a stethoscope is mandated)
  • There is no direct remuneration for acquiring the skills to use the dermatoscope and no MBS billing number for using it (there are some cases when there are Meidcare items for clinic US use)
  • The dermatoscope is at least ten times the cost of a stethoscope (US ranges from dermatoscope cost second hand to ten times again).
  • Patients appreciate you taking the extra time to use comprehensive equipment for a comprehensive examination

Where my comparison falls down:

  • Dermatoscope examines only one organ (although stethascope only really does 4 – heart, lungs, bowel, blood vessels). POCUS does them all (even brain with optic nerve diameter measurement!)
  • Dermatoscope use is not as broad in the medical family as stethascope or POCUS, only GP and dermatology.

 

Exporting images from older US machines

If, like myself you have a old machine, it may not talk easily to a modern computer.  My 2004 General Electric Logiq 100 apparently could talk to computers via a parallel port and a Windows 95 program however I would need a legacy computer just to talk to it, even if the program was available!

My machine does output a analog video signal however, provided for use with a thermal printer or a external monitor.Mini-CDVR-VideoAudio-Recorder-Motion-Detection-TF-Card-Recorder-for-IP-Camera-Blue_800x800

These C-DVR sell on ebay for USD15-25, coming with leads in and variably a manual and 12V power pack.  They seem popular for those recording video for drone flying.  Video comes out of the co-axial port on the back of the machine, into this blue box and onto a mini-SDHC card.  There are no real controls – if there is video coming in and 12V power to the C-DVR it is recording.  All live video coming into the box is recorded as an .AVI, you can then transfer the card to a computer and view with a program like VLC or MediaPlayer.

C-DVR installed on US machine
C-DVR installed on US machine

It is working well for me, only fault is that I have not worked out how to get rid of the time stamp on the bottom of the saved video.