POCUS Skin and Soft Tissue

Transcript

• 00:00Hi, my name is Julie Leviter.
• 00:03I'm an assistant professor of
• 00:04clinical Pediatrics at Yale and
• 00:06I'd like to talk to you today
• 00:08about point of care ultrasound or
• 00:10pocus for skin and soft tissue.
• 00:11So your first patient of the day
• 00:13is a 15 year old male with red
• 00:15tender lesion of his ankle as shown.
• 00:18Now it's not obvious to you on exam
• 00:20whether there is an underlying Abscess
• 00:22or if this is simply Cellulitis.
• 00:24How do we tell whether we should
• 00:26just give antibiotics or if we need
• 00:28to perform an incision and drainage?
• 00:30We can use focus. Here
• 00:32are some indications for when you
• 00:34would use pocus for skin and soft tissue.
• 00:36So the first indication is to differentiate
• 00:39Cellulitis versus an Abscess.
• 00:40Figure out if you're just going to give
• 00:43antibiotics or if you also need to perform
• 00:46a drainage procedure.
• 00:48The next is to identify the location
• 00:50and size of the Abscess that
• 00:53can help to direct any procedure
• 00:55that you're going to perform.
• 00:57The next is to identify the presence
• 00:59and location of foreign bodies,
• 01:01thereby helping you to remove them,
• 01:03and the last is too.
• 01:05As I mentioned before,
• 01:06guide your Abscess drainage
• 01:08and your foreign body removal.
• 01:12Let's talk about what skin
• 01:14and soft tissue focus is not meant to
• 01:17do. One is that it's not meant to
• 01:20differentiate Cellulitis versus edema.
• 01:22This is going to look very similar
• 01:24or exactly the same on ultrasound,
• 01:27and so you're going to have to use
• 01:30other clinical and historical clothes.
• 01:32Another thing that skin
• 01:33and soft tissue pocus is
• 01:35not meant to do is to differentiate
• 01:38Abscess versus hematoma.
• 01:39Again, these can look very similar.
• 01:41An ultrasound and you're going
• 01:43to have to go with historical
• 01:45and clinical cues. So
• 01:48how do we practically go about
• 01:50scanning skin and soft tissue?
• 01:52We're going to use a linear probe.
• 01:55That's because it's high frequency and
• 01:57we want good resolution of
• 01:59those superficial structures.
• 02:00We're also going to put a tegaderm on it.
• 02:04It is not cool to get the probe
• 02:07covered in Mersa or COVID-19.
• 02:09The first thing I want you to
• 02:11do when you start this scan is
• 02:14to adjust the depth and gain.
• 02:16You'll notice that this depth
• 02:18is 4 centimeters,
• 02:19so we're going to get great
• 02:22resolution of those structures.
• 02:23Of interest in the superficial
• 02:25skin and soft tissue,
• 02:26one rule is to start though
• 02:28at about 5 to 6 centimeters,
• 02:30and then decrease your depth to hone
• 02:33in on the structures of interest.
• 02:35Otherwise you might miss something
• 02:37deeper then you want to turn up your
• 02:40game to make sure you can visualize
• 02:42your object of interest with good resolution.
• 02:46Once you've optimized your depth and gain,
• 02:49I want you to fully interrogate
• 02:52your area of interest.
• 02:54Now this doesn't mean just scan the area
• 02:57that looks abnormal on visual inspection,
• 03:00fully sweep through the area because
• 03:02you might find an Abscess adjacent to
• 03:05that area that looks abnormal visually.
• 03:07So scan it in short axis and then
• 03:10rotate 90 degrees and scan in long
• 03:13axis and two perpendicular planes,
• 03:16then measure.
• 03:17Any kind of fluid collection in
• 03:20three dimensions apply color,
• 03:22Doppler and optionally compare
• 03:25to the contralateral side.
• 03:28So now we're ready to scan.
• 03:31Let's first take a look
• 03:33at what normal tissue looks like.
• 03:35Here is someone's chest wall. This very top
• 03:39layer is the epidermis. Then we
• 03:42have some fascia and subq tissues.
• 03:44Nicely layered hypoechoic with linear,
• 03:47clearly demarcated sort
• 03:48of facial planes in there.
• 03:51Then we have the deep fascia layer,
• 03:54a little more hyper, hyperechoic and linear.
• 03:57Here we have some muscle,
• 03:59note the striations going from left
• 04:02to right and then we have bone.
• 04:05It's echogenic with acoustic
• 04:08shadowing posteriorly.
• 04:09Here's the calf of a four year
• 04:12old boy with pain, redness,
• 04:14warmth, and induration.
• 04:15Does this look different
• 04:17from the previous slide?
• 04:18It should.
• 04:19Those nice bright white lines of
• 04:21the fascia layers have disappeared.
• 04:23Now you have this black anechoic
• 04:26fluid tracing within the tissue.
• 04:28This is called cobblestoning.
• 04:31How about this scam?
• 04:32This is a 5 year old boy with buttock pain,
• 04:35redness, warmth, and induration.
• 04:37First of all,
• 04:39aside from the obvious circle
• 04:41in the center of the screen,
• 04:43which we'll get to in a second,
• 04:46what do you make of this tissue architecture?
• 04:50Notice how those nice bright
• 04:52fascia layers have disappeared,
• 04:53and now it looks homogeneous,
• 04:56so this is caused by the inflammation
• 04:59and this sort of anechoic fluid
• 05:01collection with a heterogeneous
• 05:04inside that is an Abscess with pus.
• 05:07Take a look at this slide.
• 05:10Look how bright it looks posteriorly.
• 05:13So what artifact is this?
• 05:16This is called posterior
• 05:18acoustic enhancement,
• 05:19so this happens posterior
• 05:21to a fluid collection.
• 05:23Any kind anywhere in the body also occurs
• 05:27in the bladder and the gallbladder,
• 05:30but here this can help us
• 05:34differentiate Abscess versus
• 05:35Cellulitis in cases when the pus
• 05:38inside isn't as hypoechoic or
• 05:40obvious as in the previous slide.
• 05:47So before we spoke about
• 05:49to have a complete scan,
• 05:51we not only have to fan through
• 05:53in two perpendicular planes,
• 05:55but we also have to measure the
• 05:57object of interest and apply color.
• 06:00So let's talk about that right now.
• 06:03So here is an illustration of how
• 06:06we need to measure our object
• 06:08of interest in three planes.
• 06:10So here on the top of Mount Upper
• 06:13left you see depth and width
• 06:15measured and then in the bottom
• 06:18right we're measuring the length.
• 06:24Here we are applying color Doppler.
• 06:27Now this is important to
• 06:30distinguish this structure from,
• 06:32for example, a blood vessel,
• 06:34a lymphatic structure,
• 06:36even a pseudo aneurysm or a mess.
• 06:39All of these potential alternative
• 06:42diagnosis would be expected to have
• 06:45some flow and should definitely
• 06:48not be incised as you would and.
• 06:51Abscess another thing that you can do
• 06:55to differentiate is to apply pressure
• 06:57and look for the swirl sign or the
• 07:00movement of the contents inside.
• 07:03So this will happen in an Abscess and
• 07:05it won't happen in a lymph node or
• 07:08mass or pseudo aneurysm or lymphatic
• 07:11malformation or something like that.
• 07:16So let's talk a little bit more about
• 07:20some of these potential pitfalls.
• 07:22So is this an Abscess?
• 07:24No, this is a lymph node.
• 07:26How can we distinguish this from an Abscess?
• 07:29Will usually it's more Oval or round.
• 07:32Morse well circumscribed, it doesn't
• 07:34swirl on compression,
• 07:36and you can see this hilar vascularity
• 07:39that will light up with color Doppler.
• 07:43How about this one? Is this an Abscess?
• 07:46You might see some pockets of
• 07:49hypoechoic fluid, but not as much
• 07:52as you would see in an Abscess,
• 07:55and there is some blood flow,
• 07:58whereas we would expect an Abscess
• 08:00not to have blood flow through it.
• 08:03So this is a lymphatic malformation,
• 08:06something you definitely would not
• 08:08want to incise and would want to
• 08:12follow up with radiology. Study.
• 08:14Now, before applying color Doppler,
• 08:17we might have misdiagnosed this
• 08:19person with an Abscess as well,
• 08:21but now that we've applied color Doppler,
• 08:24we can see what's called the Ying
• 08:26Yang sign of a pseudo aneurysm.
• 08:28Again, not something that we want to inside.
• 08:33So here's a case.
• 08:34We have a 10 year old girl
• 08:37with a breast Abscess.
• 08:39It was actually seen at an outside hospital.
• 08:42They performed an Ind,
• 08:43but it didn't reveal any pus,
• 08:46just some blood and they were transferred.
• 08:48Now to your hospital or for
• 08:51some further management.
• 08:52So when you apply your ultrasound,
• 08:54you notice that the pocket of fluid does
• 08:58not correlate with where it might seem
• 09:00that there was an underlying Abscess.
• 09:03On visual and physical exam.
• 09:07So this has been found in the
• 09:10literature to be true as well.
• 09:13This was a prospective randomized
• 09:15clinical trial of patients in an
• 09:17academic emergency department.
• 09:19Patients presenting with an
• 09:20uncomplicated skin soft tissue,
• 09:22Abscess requiring drainage diagnosis
• 09:24was either by physical exam by
• 09:27bedside ultrasound or by both and
• 09:29those randomized to the pocus group
• 09:31had Ind performed with bedside
• 09:33ultrasonographic imaging of the Abscess.
• 09:35Those in the non pocus.
• 09:38Group had Ind with physical exam alone.
• 09:41Now there were 125 patients
• 09:43enrolled 54 in the focus group and
• 09:4753 in the non focus group.
• 09:49They found that the Pokus group
• 09:52was less likely to fail therapy.
• 09:54The focus group had a four point 8%
• 09:58failure rate and the physical exam
• 10:01group alone had a 16% failure rate,
• 10:04so this is likely because pocus guidance
• 10:08facilitates the identification of the
• 10:10Abscess pocket and allows for better
• 10:13planning of the initial incision.
• 10:16So,
• 10:16just to recap,
• 10:17the first thing we want to do when we're
• 10:20doing a skin and soft tissue ultrasound
• 10:23is cover the probe with a tegaderm.
• 10:25Then we're going to scan in two planes,
• 10:28fully interrogate the area of interest we're
• 10:31going to measure the dimensions in 3D,
• 10:33apply color Doppler check for the swirl sign,
• 10:36and don't be fooled.
• 10:37If anything doesn't look like you would
• 10:40expect an Abscess to look like and has
• 10:43any other signs like color flow through it.
• 10:46Then be sure to follow up
• 10:50with radio radiologic imaging.
• 10:52Let's talk next about using
• 10:54ultrasound for foreign bodies.
• 10:56It actually has a fantastic
• 10:58sensitivity of 80 to 90%.
• 11:00It's very useful for finding
• 11:02radiolucent foreign bodies like wood,
• 11:04plastic, and cactus spine.
• 11:06But remember,
• 11:06if you don't
• 11:08see the foreign body that you're
• 11:10looking for on ultrasound,
• 11:12make sure to get an X ray just to
• 11:16make sure that nothing is missed.
• 11:19And remember. Pocus is also useful in
• 11:22real time for foreign body removal.
• 11:30So what do you see here?
• 11:34So at the top of the screen you see
• 11:36a hyperechoic linear structure that
• 11:38doesn't look like it's part of the
• 11:42muscle tissue that we're seeing here.
• 11:44This is a retained needle.
• 11:48This next patient is a 5 year
• 11:50old boy with a red tender area
• 11:52on the bottom of his foot.
• 11:53What do you see?
• 11:56So where are these arrows are pointing?
• 11:59Are the two perpendicular
• 12:00views of a retained splinter,
• 12:02so also notice that there is a small
• 12:05anechoic rim as well as some other
• 12:08pockets of fluid that we're seeing.
• 12:11Superficially this is likely some
• 12:13fluid or pus that's collected
• 12:15around the splinter plus adima or
• 12:17Cellulitis based on the ultrasound
• 12:19findings and clinical context.
• 12:21I'm thinking this splinter needs
• 12:23to be removed and that this kid.
• 12:26Needs antibiotics after removing
• 12:28the foreign body makes sure
• 12:30to scan again to ensure that
• 12:33you've removed the whole thing.
• 12:36This is a nice example of two
• 12:38artifacts that are frequently
• 12:40seen with foreign bodies,
• 12:42so the first is reverberation artifact.
• 12:45So this happens when there are two
• 12:47reflectors parallel to each other and
• 12:50perpendicular to the ultrasound wave and
• 12:52the sound gets trapped between these
• 12:55two echogenic surfaces bounces back
• 12:57and forth before returning to the probe.
• 13:00So since it takes more time to get back,
• 13:04it seems that.
• 13:05Each successive bounce
• 13:07comes from a deeper place,
• 13:09so that's where you're seeing
• 13:11that sort of triangular cone of
• 13:14brightness posterior to that object.
• 13:17That's more superficial.
• 13:20So the other artifact that we're
• 13:22seeing here is acoustic shadow.
• 13:25That's all that black area behind
• 13:27the object up on top of the screen,
• 13:31and that's because the object is preventing
• 13:34the sound waves from passing through.
• 13:36So this example shows a chemotherapy
• 13:39port so it didn't get there by accident.
• 13:43But I thought this was a really
• 13:45nice example of both reverberation
• 13:48artifact and acoustic shadowing.
• 13:50Both of which you can see
• 13:52with foreign bodies.
• 13:55So here's one last example.
• 13:57This is an 8 year old girl
• 14:01with a red painful earlobe.
• 14:03So look at whether it where
• 14:06this arrow is pointing.
• 14:08There's a hyperechoic structure
• 14:10at the top of the screen that is
• 14:13in Piper echoic metal earring,
• 14:16and this also shows that nice
• 14:18posterior acoustic shadowing
• 14:19and reverberation artifact.