Midterm: DSA: Intro to POCUS

Question 1

What is the biggest pro for using POCUS?

Answer 1

Improves diagnostic accuracy
Decreases overall cost of care
Decreases time to diagnose

Question 2

What are some cons to POCUS?

Answer 2

Operator dependent
Limitations
–poor image quality with fat and air

Question 3

Describe the physics of ultrasound waves?

Answer 3

1. Electricity causes vibrations of crystals, which travel through fat and air, and will bounce off of objects.
2. This wave will then vibrate back to the probe which is picked up
   - areas that bounce back=white
   - areas that don’t=dark!

Question 4

How are frequency and wavelength related?

Answer 4

Higher the frequency, the shorter the wavelength

Question 5

Which type of frequency waves penetrate deeper into tissues?

Answer 5

Lower frequency waves penetrate farther, but have worse quality!

Question 6

Which frequency and wavelength combo gives you the highest quality for US?

Answer 6

Highest frequency, shorter wavelength=clearer picture

Question 7

Rank the probes in order from high frequency to lowest frequency.

Linear, Phased or “cardiac”, and curvilinear or “abdominal”

Answer 7

1. Highest=Linear
2. Middle=Phase or cardiac
3. Lowest=curvilinear or abdominal=penetrates farthest into fat

Question 8

What is echogenicity?

Answer 8

The ability of a structure to reflect sound waves

Question 9

Define: anechoic, hypoechoic, and hyperechoic

Answer 9

anechoic=complete lack of returning waves
-fluid

Hypoechoic=very few echos=fat

Hyperechoic=very bright
-stones, bones, denser tissues

Question 10

What is acoustic shadowing?
When does it occur?
Why does it occur?

Answer 10

• Common Artifact
• Occurs when waves encounter a reflective surface (stone or bone), making the area behind it hypo or anechoic
• due to very few sound waves getting through

Question 11

What is posterior acoustic enhancement?

Answer 11

The increase in echogenicity that occurs deep to an anechoic structure
-due to very few waves being reflected

Question 12

What is edge artifact?

What is it seen with?

Answer 12

Sound that is bent by a structure in parallel with the ultrasound sound beam, resulting in the appearance of a shadow behind the surface
-generally seen with fluid filled structures, like gallbladder

Question 13

What is mirror artifact?

Answer 13

Happens with highly reflective surfaces causing a mirror image of the object distal to the probe
-usually appears at bottom of screen

Question 14

What is reverberation artifact?

Answer 14

Multiple intermitting lines or “echoes” running parallel to the actual needle
-usually due to line placement

Question 15

How do you orient the probe in longitudinal scanning?

Answer 15

Probes will have an orientation marker usually on right!

-longitudinal scanning is marker toward head

Question 16

How do you orient the probe in transverse scanning?

Answer 16

Probes will have an orientation marker usually on right!

-Transverse scanning is with probe facing patients right

Question 17

What side of the probe do you use to orient yourself in transverse scanning for cardiac probe?

Answer 17

Screen marker is on the left!

-only exception, rest of probes are on the right!

Question 18

What is ALARA?

Answer 18

As low as reasonably achievable exposure

-basically only scan people for as long as you need to at the lowest possible dosing

Question 19

What is the purpose of a FAST scan?

Answer 19

To detect free fluid where it shouldn’t be!

-trauma!

Question 20

Where will blood pool in the abdominal cavity (ie, most gravity dependent spot?

Answer 20

Morrison’s Pouch

-between kidney and liver