Clinical Case 109: Eyes, Air and Ultrasound

A quick case that shows how we can use ultrasound in clinical assessment of eyes and why US makes me look like a better doctor.

30 year old woman – was punched in the face 3 days ago at a disco.  She sustained a small laceration over the inferior orbital rim – but went on dancing.

The next day she awoke with a really swollen face, unable to open her eye at all.  The laceration had sealed itself  – so she decided to wait a few days to “see it it would get better”.  That is the type of people we see a lot of in Broome!

By day 3 the swelling was no better and she was beginning to get a bit annoyed by the pain and inability to open her eye…  so off to ED.

The left eye was severely swollen – despite analgesia and a firm hand – the best I could do was glimpse the sclera and a bit of cornea.  She had a small subconjunctival haemorrhage, no hyphema and a clear looking cornea [in the half second that she tolerated my prying her lids apart.]  Far from an ideal assessment.  So how do you assess an eye that is occluded by swelling in the middle of the night?  Ultrasound of course!

Here is a rough guide to looking into eye trauma using the US machine.

  1. Linear probe set to 4 – 5 cm depth.  “Small parts” preset works OK.
  2. Get heaps of gel onto he probe / upper lid (use cooled gel if you want to make a gel heap as a stand-off pad.)
  3. Easiest to have the patient supine with pillow to stop the head moving.
  4. Set the gain to make the vitreous black, however it can be useful to turn it up if you are looking for subtle intra-vitreal bleed etc
  5. Scan over the upper lid fanning from superior to inferior, then in sagittal plane from side to side.

There are some cool things you can do with ocular US when the eye is unexaminable:

– Assess range of extra ocular movement.  This is really important for assessing for rectus entrapment.

– Assess pupil response (check out the video here)

So I went through my routine and scanned the closed eye.  In trauma I look for the following injuries on my scan:

  • lens dislocation,
  • retinal tear,
  • intra-vitreal bleed / detachment,
  • globe rupture and
  • retrobulbar haematoma [tip is a "guitar pick-shaped" posterior globe]
  • Check the optic nerve sheath diameter (ONSD)

As I was scanning the orbit I kept getting this weird artefact – thought it was maybe due to some cellulitis or loss of contact – but it “just didn’t look right”.

So when I do a scan and it is “not quite right” I tend to imagine the worst case scenario.  I was seeing a normal eye with good pupil response, extra ocular movement etc. No pathology – just this odd artefact that obscured my views.  So I decided to investigate further.

Here is the CT of her orbit: Clearly an inferior orbital fracture with a nice teardrop of fat extruding into the antrum.

And you can see quite a bit of air that has escaped into the orbit – which was the sourcephoto-2 copy of my mystery artefacts.

So I thought I had just discovered a new sonographic sign – but of course I was wrong.

There was a paper published on this phenomenon way back in AJEM, 2004 from Michael Blaivas et al (here)

So I managed to fluke finding air in the orbit – though I wash’t really sure what I was seeing!

Lessons learned here:

  1. If you are not sure what you are seeing – don’t ignore it! It might be the key to the diagnosis
  2.  Air in the orbit equals blowout fracture and looks like a dirty gas shadow (kinda like bowel in the orbit)
  3.  Correlate your bedside scan with formal images and you will learn a lot faster.

Happy scanning

Casey

Lung Ultrasound with Dr. Kylie Baker

For about a year now I have been spending time “working” for the Ultrasound Leadership Academy – run by the team from the Ultrasound podcast.  It is really cool to be able to chat with enthusiastic US learners all over the globe about the clinical coal-face of US in medicine.  One question I get asked a lot: – what is the most useful US modality for me?

Well I reckon that lung US is now a clear winner.  Why?  Because it is so useful in really common, everyday scenarios.  It does guide diagnosis and also therapy and can be a life-saver from time to time.  A lot of the other uses of ED Bedside US are applied in less common situations and may not really effect outcomes in a lot of patients [I will get in trouble for saying that!].

So I feel that lung US is the thing I would teach to a keen MEd Student if they asked me to give them one US skill to make their early postgrad years go better.  But the problem is that this is a relatively new concept – unless you are from Europe – where it has been going on for 20 + years.  But for the English-speaking world it is pretty new and just making its way into clinical algorithms.

There are a few problems to overcome when learning lung US;

  1. The set-up on your machine is unlike any other that you have used before [mostly there are no pre-programmed modes.]
  2. It is all about artefacts – we are looking for things that are not really there – patterns in the smoke that represent various entities, rather tun actually visualising the “real anatomy”
  3. There is a steep learning curve… clinical correlation is required
  4. This is like many US uses – very user-dependent.  It takes practice to get consistently good images.

Luckily [for me and you] I had the good fortune of bumping into Dr Kylie Baker a few weeks ago at the ASUM [Australasian Society of US in Medicine] Conference in Melbourne.  Kylie is an ED doc from Ipswich in Queensland and has been contributing pearls to the Intensive Care Network on lung US in critical care.  So I put her on the spot and asked her some really dumb questions about lung sonography!  The result is this podcast.

I highly recommend having a listen if you are at all interested in improving your ability to treat patients with acute chest disease.

Here is a basic “How To” list that I have compiled from my discussions with Kylie.  You need to know how to make your machine do chest scans  – this is the quick guide for dummies.

(1)  Patient: enter patient ID and data for future ref and learning.  Review is crucial to learning!

(2)  Probe: select curvilinear probe initially for routine 8 zone scan

(3)  Position: patient supine / semi-supine. If they can sit for posterior scans – great. Depends on clinical context and your diagnostic goals.

(4)  Settings: TURN OFF any automated features that may decrease artefacts – e.g.. Tissue harmonics, multi beam, sonoCT, minimise greyscale range

(5)  Preset: Abdomen is OK. [NB: Lung preset on newer machines is really only optimised for pneumothorax scans - not other lung scanning.]

(6)  Depth: 10 – 12 cm in a normal sized person. You may need to adjust this if your machine has a fixed focal depth

(7)  Focus – aim to focus on the pleural line. (If this is fixed – then decrease depth to bring pleura close to mid screen.)

(8)  Frequency: push the probe to the lowest (Penetration) frequency possible.

(9)  Hand position: visualise the pleural surface and aim to keep the beam perpendicular to he pleura. [for pneumothorax - a slight angle may help] ***The absence of “A lines” suggests an incorrect setup or too large an angle on the pleura

(10)  The scan: Sample each of the zones (2 anterior, 2 lateral +/- posterobasal on each side)   If abnormalities are found – esp. focal changes – then this area can be further interrogated with a more thorough scan or a linear probe

Other great resources on Lung Scanning :

This from the Queen of Lung US – Dr Vicki Noble via Ultrasound Podcast – there are 2 parts to the lecture

Back to Basics on the Lung artefacts with Dr Mike Stone (the other Mike) of US Podcast – also a 2 part deal.

Some great pointers from Dr Rob Arntfield from Western Uni IN Canada at Western Sono tutorials. This video shows the positions of the probe well.

And guess what – all of these great lung US teachers are also “professors” with me at the Ultrasound Leadership Academy.  Check it out if you want to take your US skills to the next level.

If you have questions, comments or your own Lung US pearls – then please share on the comments below

Big thanks to Dr Baker for her time and expertise

Casey

Clinical Case 108: Planes, Drains and Pneumothoraces

Another case inspired by a Twitter debate today.

A Tweet Case was put forward by @FlyingDrBen  (Ben Darwent) who is based in Perth WA – home of LITFL. My friends Minh le Cong, Karim Brohi and Tim Leeuwenburg started a discussion around the case.  Fair to say it got way too big for twitter!  So I am posting this case to get you all thinking and source expertise on the topic.  Here we go…

Rodknee is a 27 yo. man who has presented to a remote hospital following an “incident” in which his girlfriend stabbed him in the right lateral chest with a small kitchen knife ( ~ 12 cm blade).  She apparently found out he had been sleeping with his wife despite his assurances to the contrary.  The oldest story in the book!

Rodknee is a stoic individual and managed to sober up and have a sleep before presenting to the ED about 3 hours after the injury.  There was not much blood loss at the scene and he managed to patch things up with his +1 in the meantime.

On arrival his Obs are all normal ( P = 70, BP = 125/80, RR 14, SpO2 = 99% RA, he is well perfused and alert.  He does complain of some pleuritic pain on inspiration over the site of the wound.  On inspection he has a very neat stab wound ~ 2cm long at the anterior axillary line – 6th intercostal space.  There wis no active bleeding or bubbling.

The attending Doctor is a semi-retired GP from an affluent Sydney suburb who is doing a few locums “for fun” to round out his career.  He has asked for your advice – fortunately you have a High-def VC link up to their ED which is about 250 km away.   So you have a virtual look at the patient.  He is as advertised.

Being an ultrasound enthusiast – you talk the locum through a FAST scan and look for a pneumothorax / haemothorax.  The very rough and ready images reveal a tiny right pleural fluid collection (less than a centimetre) and no clear pneumothorax – although it is hard to exclude in a mobile vertical patient who is 250 km away!  So we think he has a small haemothorax and either no pneumothorax – or a very small pneumo we have not been able to find on US.  He remains haemodynamically stable.

The locum is super keen to get Rodknee transferred out to your bigger ED ASAP – he is the solo cover and has been up all night already.  Fair call – lets get the aeromedical team in to swoop and run.  But……   what about the potential pneumothorax?  Does it need a drain before we put this chap on a small plane?  The textbook says it will expand and might cause tension effect if it does.

Just out of interest – you ask the locum if he is comfortable with placing an ICC if required…  he tells you that he last did one in 1979.  Then he starts waving a metal trocar around like the Swedish chef from the Muppets!  Hmmm, maybe not so soon!

So here is the question – is it better to perform a prophylactic intercostal catheter in a well lit ED under sterile conditions, OR should we fly him without an ICC.  What is the risk of his developing a tension pneumothorax or becoming hypoxic is his possible pneumo expands?

Is a drain mandatory for a 30 minute flight in a small aircraft that will be going to altitude?

Controversial!  Lets hear your thoughts.

Casey

 

Clinical Case 107: Subarach Sans Scan

This case is inspired by a Twitter conversation started by Dr Brent May ( @DocBrent ) – he is an Anaesthetist and motorsport doc in Australia.

Brent asked the simple question: “SAH Q – no CT available. What is the “usefulness” of RBC count on LP? Lab “unable to do xanthochromia”.  This is a real problem in many hospitals – especially the smaller places with no CT or specific lab crew.  So lets look at a case and try to get to the bottom of this one!

You are working in a remote clinic with a small Emergency area.  It is a slow day.  You are 400 km from the closest hospital which has a CT and laboratory services.

headache-388870_1280

Jan is a 45 year old local woman.  She presents with a bad headache – this is not usual for her, she is not usually a “headachy” person. No PMHx of migraine or other headache syndrome.  It woke her from sleep this AM – about 4 hours ago. Maximal intensity from the onset.  She says it has not responded to simple analgesia and resting at home.  She has had no syncope or neurological symptoms.  The headache has remained relatively constant.  She is complaining of neck stiffness – though has normal ROM in her neck.  She has no fever, vomiting or photophobia.

On examination she has no neurological signs.  Her obs are all normal, BP = 140/85, afebrile.  You cannot reproduce any objective neck stiffness.

So – first question.  Based on that clinical info – what would you estimate Jan’s “probability” of having a subarachnoid haemorrhage ?  Have a Gestalt guess… 2%, 5%, 10%, 50 %???

How low would you want your “probability” to be to avoid a transfer and subsequent work-up?  i.e.. what is your lower test threshold for SAH? 1:100,  1: 1000, less?

Here is a copy of Perry & Steill’s landmark paper in the BMJ 2011 – check out tables 1 & 2.  Jan is pretty much a “average Jan” for the cohort of 3000 pts in their paper.

About 7.7  % ended up having a subarachnoid bleed – and another 2 – 3 % had another non-benign cause for their headache.  So 10% is a reasonable “pretest probability” for badness in Jan’s case.

Now a 10% risk of serious intracranial pathology.  That would mandate a work up in most places.  Unfortunately your hospital only has rudimentary lab gear – you can do an LP and get red cell counts, but not xanthochromia.   A CT would be helpful if you can do it in less than 6 hours – but even if you called for transfer now – it would be well past 6 hours by the time Jan made it into the doughnut 400 km away.

So here we are.  You can do an LP and get red cell counts on the CSF.  Xanthochromia is probably not helpful as it is early (less than 12 hours) and simple visual inspection for yellow change is inaccurate. [Best read by non-colour blind female lab techs apparently!  Can you ask for that on the forms?]  Most Australian labs use automated spectroscopy to analyse for xanthochromia – and this is usually only available in larger, tertiary labs.

The accepted gold standard diagnostic features of SAH are variable – but the Canadian group who do a heap of research use the following:

“Subarachnoid haemorrhage was defined by:-

- subarachnoid blood on unenhanced computed tomography of the head,  OR

- xanthochromia in the cerebrospinal fluid,  OR

- red blood cells (>5×106/l) in the final sample of cerebrospinal fluid,

PLUS  an aneurysm or arteriovenous malformation evident on cerebral angiography.”

So now the big question.  Is there any way that you can effectively “rule out” SAH in Jan without transferring her 400 km to the next hospital?

Does a low CSF red cell count allow us to “exclude” SAH?  Can we use any other tests to decrease the risk for Jan?

Tough yet common problem in many rural areas in Australia.  I would love to hear your thought and comments below.  Does it depend on the timing?  Can we watch and wait if the initial LP is clear?  Or do we need to get imaging and a review for xanthochromia on all the Jan’s we see in ED?

If you are interested in the diagnostic dilemma that is the “SAH work up” then I highly recommend listening to David Newman’s SMART EM episode on the topic from way back in 2010. (WARNING: it is nearly 2 hours of podcast!)

Let me know what you think

Casey

A Chat with Dr Jim McDonald

Gday team.

This is a conversation I had with my mate and mentor Dr Jim McDonald.  Jim is a 45 year veteran of GP.  Based in Melbourne – he has worked all over the country as a rural locum.  He has delivered over 4000 babies in the suburbs of Melbourne and trained countless GP registrars over the years.  In 2015 Jim was awarded the Order of Australia for his service to Medicine.

Jim is a deep thinker – so I asked him to come up with his top 10 pieces of advice that he would give himself if he could go back 40 years.  I think we got past a dozen or so – but nobody was counting as the pearls flew all over the place.

So if you are a GP trainee, or any sort of doctor – then have a listen to this.  Plenty of great advice for us all

Enjoy.  Casey

Strept throat: Global Paeds Hangout

After the post on Strept throat, Swabbing and Such last week – I have recorded a longish podcast with a gang of international PAeds FOAM crew: Drs Damian Roland,  Seth Trueger and Melanie Thompson.  They joined me for a chat about all things to do with pharyngitis in kids – the diagnosis, the work up, swabbing, antibiotics, communication with parents, training JMOs and role modelling – we covered it all!

It is an enlightening discussion that takes in some large global practice variation and puts in the context of our local tropical Australian endemic strept disease.

Here is the podcast:

The references are mostly in the previous blog post on the topic from last week

Additional references you might want to check out:

Seigel et al from NEJM 1961 – last Paeds trial that actually had a case of ARF in its cohort I could find.  About 1200 kids with throat infections – 2 got ARF and 1 got APSGN [both in the control group.]

Dr Mel’s SMACC 2013 PK on “Keeping Up with the Jones” – refresh your Jones criteria for rheumatic fever.

Big thanks to the team – @Damian_Roland @MDAware and @dr_mel_t  – hit them with any questions or comments on the post below or tweet it right at them – they are all very friendly !!

 

Casey