Abdominal, Critical Care, ED, Emergency medicine, Videos

Small Bowel Obstruction on ultrasound

Great case of the week from Yale EM Ultrasound. This is a great POCUS education site.

Hyperactive, dilated small bowel loops with free intraperitoneal fluid. (c.f. paralytic ileus where bowel loops are dilated but static)

ED, Vascular

DVT 101

Looking for deep vein thrombosis (DVT) of the lower extremity is a common request. The most important aspect of a DVT ultrasound is the compression of the vein.

On ultrasound, vessels look black, or anechoic, due to the fact that they are fluid filled. You can also use colour Doppler to see the flow of blood within these vessels.

Holding your probe in transverse on the patient’s leg, find the common femoral artery and vein at the proximal thigh. By applying firm pressure with the probe to the patient, the vein should easily collapse. Follow the vein from the thigh to behind the knee, to the popliteal vein.

sfv-comp-norm.jpg

However, if the vein does not compress, this should raise suspicion for a DVT. Often, you will be able to see clot within the vein, as the vessel is no longer anechoic, but filled with hypoechoic clot. Also, if you turn on colour Doppler there will be no colour flow within the vessel.

DVT +

clot

Images:

http://www.nuemblog.com/dvt

https://radiopaedia.org/cases/lower-limb-deep-venous-thrombosis-dvt

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Equipment

What’s in a name? Different types of ultrasound probes

Types of Probes:

There are three main types of ultrasound probes: curvilinear, linear and phased.

Curvilinear. This is a low frequency probe with a curved face. Typically used for abdominal, gyne, obstetrical and pleural scanning. The curved face gives and increased field of view, while the lower frequency allows for better penetration.

Linear: High frequency probe with a flat, rectangular face. Used for vascular, small parts and musculoskeletal scanning. Due to shape of probe, image is rectangular, not a curved arc. *Tip: Most units have an option to make the image widescreen, increasing the field of view.

Phased: Low Frequency rectangular shaped probe with a small face. Primarily used for cardiac scanning (echocardiography). The small face of the probe allows it to fit between ribs, but the arrangement of crystals creates a curvilinear field of view.

Abdominal, ED, Emergency medicine

Aorta and IVC

Ultrasound can be used to assess the main vascular structures in the abdomen. The most common examination is to look for an Abdominal Aortic Aneurysm (AAA).

To find your aorta, start by placing the probe on the patients’ abdomen in transverse, just below the xiphoid process. You will see anechoic oval and circle, above a crescent shadow. These represent the IVC, Ao and Vertebra, respectively. Using firm pressure, slide probe downwards toward the umbilicus, at which you should see the Ao bifurcate into the Iliac arteries. Once found in transverse, try this motion while the probe is in the sagittal plane.

AO IVC TRaortanormal

 

 

 

 

 

An aortic aneurysm is a focal dilation of the Aorta, and should be greater than 3.0 cm when measured from anterior to posterior.

aaa

The IVC is located just right of midline, and can be seen by the liver. It is best appreciated in the sagittal plane. Notice how the IVC is phasic, changing size with respiration. If you ask your patient to breathe in, or “sniff”, you should see the vessel collapse more than 50%, demonstrating a normal venous pressure.

C60_Liver_IVC_Midline[3]_1

Images:

http://reference.medscape.com/features/slideshow/ultrasound

http://www.sonosite.cn/clinical-media

 

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Equipment, Tips and Tricks

Image Optimization

Depth, Focus, Gain

When it comes to image quality, if you follow these easy steps for every image, you can’t go wrong! First, adjust your depth. Is the structure you are imaging, say the aorta, way at the top of the screen? Decrease your depth so your image ends just below the area of interest. Is the lower pole of the kidney cut off? Increase your depth to include a few centimeters below the kidney border.

Now that you’ve adjusted your depth, apply the focus! By tapping or twisting the focus knob, place your focal zone at or just below the structure of interest. This will place optimal resolution at the organ you want to see.

Finally, tweak the gain. Usually a dial on the main console, twist to increase or decrease the brightness of the image. Your goal: Make anechoic structures, such as vessels or the bladder black, but still bright enough to see surrounding structures.

With these three steps, your images will be picture perfect!

Bringing ultrasound to the bedside