Introduction to Bedside Ultrasound

Screen Shot 2013 01 06 at 1.53.52 PM Introduction to Bedside Ultrasound

 

It’s been out awhile now, but if you haven’t seen it yet, take a look at Mike and Matt’s Introduction to Bedside Ultrasound.  The ultrasound pocast guys have released this excellent overview of point of care ultrasound through the iTunes Store.  This is certainly convenient as most of us have 3-12 iDevices on our person at any one time.  Caveats are that this means that it is available only on an iPad using iBooks 2 or later, and ios 5 or later.  Right now it is $29.99.

 

There is a lot of good content, but I think the best chapter in the book, is probably the RUSH chapter. :)

  photo1 Introduction to Bedside Ultrasound

Lung ultrasound goes viral for flu season

Zlines 300x290 Lung ultrasound goes viral for flu seasonMore lung ultrasound tips and examples from Drs. Jim Tsung and Brittany Pardue Jones!

Bacterial pneumonia will manifest as lung consolidation with air bronchograms. The A-line pattern of normal lung will begin to be replaced by B-lines in the area of affected lung:

Here we’ve highlighted the consolidation from the above video as well:

large PNA piclabel Lung ultrasound goes viral for flu season

In contrast, subpleural consolidations and confluent B-lines are more suggestive of viral pneumonia.
So what do these look like?

Subpleural consolidation:

and another example:

Confluent B-Lines:

occur when multiple B-lines coalesce. In contrast, the next example demonstrates multiple discrete B-lines.

Multiple B-Lines:

And now for something completely different

Z-Lines:  Comet tails that arise from the pleural line but DO NOT make it to the bottom of the ultrasound screen. These are not B-lines. These artifacts have not been associated with any pathology, and they do not obliterate A-lines.

For more details on the sonographic appearance of viral lung pathology, check out this article by Jim Tsung.

FAST five ways

The FAST exam is generally described as a trauma assessment (hence the acronym). But it is often used as a metanym to mean any assessment of the peritoneum for fluid. In fact when I was a resident folks would often say, “let’s FAST that gallbladder,” or “get the FAST machine so we can put that central line in.” And we didn’t have Twitter.

Anyway, here are a few cases where the “FAST” was used in a non-trauma patient to assess the peritoneum:

Cirrhotic with abdominal pain and tenderness:

who was found to have ascites, and spontaneous bacterial peritonitis

Lower abdominal pain in pregnancy:

who was found to have hemoperitoneum from a ruptured ectopic pregnancy

Diffuse abdominal tenderness in a healthy ten-year-old:

who was found to have idiopathic seromas of the peritoneum, pleura, and pericardium!

Shortness of breath and abdominal distension:

which turned out to be massive abdominal abscesses

Diffuse abdominal tenderness and distension after hysteroscopy:

which was complicated by a bowel perforation; hence fecal material throughout the peritoneum

Take home points:

  • Assessment of the peritoneum greatly aids medical and surgical diagnoses
  • Fluid appears black (anechoic) on ultrasound. Very difficult to tell what TYPE of fluid by appearance alone
  • Your clinical assessment must guide the differential diagnosis for your ultrasound findings

Spray bottle woes

spray Spray bottle woes

Here’s a quick trick:

 

When the Transeptic spray bottle won’t spray, it is often because the pump has become disconnected from the plastic tubing within the bottle. Instead of trying to fish it out with forceps, just turn the whole bottle upside-down.

Disinfectant Spray Bottle Troubleshooting from Sinai EM Ultrasound on Vimeo.

I hope this takes away just one small annoyance on your next shift. Unfortunately this will leave room for another, larger annoyance to occupy the space.

Hepatization versus Pseudo-Hepatization

Counter-intuitively, when insonating the lungs of healthy patients, we don’t “see” lung tissue. Instead we see and interpret artifacts arising from the pleural lines and the diaphragm.  These artifacts change with pulmonary disease processes.  In pneumonia, the airway spaces become inspissated with bacterial byproducts and consequently the sonographic appearance of lung tissue changes.

The transformation of lung tissue is termed hepatization: the lung tissue now appears similar to liver tissue.

This can be confusing in the lower lung fields, especially adjacent to the diaphragm because we use the mirror image artifact of the liver and spleen to indicate that lung tissue is normal. This mirrored, artifactual splenic or liver appearance could then be called pseudo-hepatization.

 

 

So, how do we differentiate hepatized lung versus pseudo-hepatized lung?

  1. Never use a single image for your diagnosis, scan through area and convince yourself (then save a representative image or clip for QA).
  2. Be systematic and scan down from the lung apices to the diaphragm.
  3. Hunt for the diaphragm and use it as a dividing line between the lung and the abdominal organs.
  4. Hepatized lung will often have a rim of fluid around it.

Image 1: Normal lung with visible diaphragm

Ultrasound of lung and spleen from Sinai EM Ultrasound on Vimeo.

Image 2: Normal lung with obscured diaphragm

Lung and Spleen Interface on ultrasound from Sinai EM Ultrasound on Vimeo.

Image 3: Hepatized lung at the lower lung field

What the Heck 3

The Shadow Knows What the Heck 3So we are scanning the left thorax in a patient with shortness of breath, in an effort to assess for pleural effusion. The following video was obtained:

The operator correctly noted the presence of a pleural effusion, and a bit of lung tissue can be seen towards the left side of the screen floating in fluid. In addition, there are THREE shadows evident, each from a different source. Can you spot them?

large LUQ pic What the Heck 3

So let’s take these one at a time, with labels:

large LUQ piclabels What the Heck 3

Shadow A

Is the easiest one. It extends almost from the first pixel at the top of the screen down to the far field. We can’t even see the characteristic echotexture of skin or subcutaneous tissue in the near field. There’s no contact here between the transducer and skin, possibly due to:

  • the probe not touching at all
  • clothing or an EKG lead getting in the way
  • not enough gel (the novice’s answer to everything but sometimes still true)

Shadow B

The most interesting one of the bunch. Probably two major factors at work here. First, this section of diaphragm is a particularly bright reflector so it can create a shadow behind it due to the sheer amount of reflection occurring. Second, the density difference between the diaphragm and pleural effusion is creating a refraction artifact, often referred to as an edge artifact. Beams of sound which were roughly parallel as they struck this interface get bent at different angles based on whether they hit the dense diaphragm or the less dense fluid. The space in between the formerly tightly spaced beams is displayed as blackness, or the absence of returning echoes.

Shadow C

That’s a rib shadow. Did you know that ribs grow back if you remove them?

 

Case- vaginal bleeding

This young healthy woman presented in her first trimester of pregnancy with lower abdominal pain and vaginal bleeding. She had diffuse abdominal tenderness and was mildly tachycardic with a normal blood pressure. After IV access was established, labs and blood bank sample were sent, and the following ultrasound of the right upper quadrant was obtained:

So there’s a bit of free fluid in Morison’s pouch. Can we make it more evident for the kids in the back row? The next image was taken with the patient in Trendelenberg position:

That made a pretty big difference.

In this sagittal view of the uterus the bladder is visible to the screen right; there is free fluid in the pelvis just to the left of this, and it can be seen to move with probe pressure on the lower abdomen.

Thus a diagnosis of ruptured ectopic pregnancy was strongly suspected, and the patient underwent emergency laparoscopy with the obstetrics service.

Check out our pelvic ultrasound and FAST tutorials for more details on performing these assessments.