Ultrasound Flashcards
When and where was ultrasound used in medicine
1950’s
Popular first in obstetrics
No ionizing radiation
Advantages of ultrasound (4)
Identify anatomical structures
Relationship of needle to tissues
May decrease time
May decrease complications
Ultrasound waves travel between_____
Travel 2-20 Mhz
Travels differently in different structures
Audible sound Hz
(Audible sound = 20-20,000 Hz)
What are the 3 things that sound waves can do when it encounters a surface (interfaces)
Transmitted
Reflected
Something in between
The sound waves that are_____ back to______ create____ recorded by the computer
The sound waves that are reflected back to crystals create impulse recorded by the computer
Anechoic
without
dark picture- transmitted sound waves
fluid
Hyerechoic
Bright
reflected
bones/stones
Isoechoic color
shades of gray
bewtween transmitted adn reflected
soft tissue/muscle/fat
Fluid on ultrasound is seen as
anechoic
What changes shape and vibrates to give us a picture
Piezoelectric crystals
Piezoelectric crystals fucntion
Inside head of the transducer
Change shape with electric impulse
Starts to vibrate
Generates sound waves
Linear array features (3)
High frequency (7-15 MHz)
Better resolution at
Superficial depth
Bundle of nerves, carotid, IJ use what transducer?
linear array
Curved array features (3)
Low frequency (2-5 MHz)
Poorer resolution
Deeper tissue
Looking at stomach or gal bladder use what probe?
curved array
Phased array features (2)
Lowest frequency (1-3 MHz)
Useful for echocardiography
Axial plane
cut body horizontal
sgittal plane
cute body vertically
What is the static approach? (3)
-identifying the target vessel, assessing patency
-marking an appropriate insertion site
-cannulating blindly.
What is the dynamic approach?
performing the procedure in real time
viewing the needle puncturing the vessel wall.
Term for posture and body mechanics
Ergonomics
How to hold probe
like a pencil
what do you put the gel on?
on the cover on the probe
What are the two ways to focus?
Gain and depth
Quality of the signal you are getting back to the structure
Gain = brightness signal quality
too dark or too bright
When the gain is adjused enough….
Twist back and forth until fluid is black and soft tissue is mid-grey
Depth measures are shown….
Depth measures are shown in cm on side of screen
what setting is a knob and what is a button
knob = gain
buttons = depth
tips for using depth
Start at high depth then work to bring object of interest into middle of screen
IN plane vs out of plane refers to______
Refers to relationship of needle to plane of ultrasound
In-Plane
transducer head and needle = parallel, see the needle for as long as the transducer head is.
out of plane
head of transducer and needle is perpendicular = needle looks like a dot
should always be in the_____ axis for procedures
long
advantages of in-plane view
See whole needle and tip
Disadvantages of in-plane
easy to be off plane
advantages of out of plane
Needle is positioned directly under plane of ultrasound
disadvantages of out of plane
Unclear where tip of needle is
View used for Central line
out of plane view
Vanishing sign
Looking for hyperechoic signal = find by scanning up and down the neck. Know that the needle is intraluminer and scan up and down the neck = see wire moving and will move inside but getting at different angle.
indications of Ultrasoundguided IV access (2)
History of difficult cannulation
Multiple failed attempts
Contraindications for Ultrasoundguided IV access
Does not substitute for IO access in life-threatening situations
which probe to use for Ultrasoundguided IV access
Linear
high frequency
Ultrasound guided IV access with linear probe exceptions
Obese = curved for deeper view
FAST
Focusedassessment withsonography fortrauma
indications for FAST
To r/o free fluid in the abdomen and pericardium
Which probe is used for FAST
Curvilinear because looking for organs
Assessment points for FAST
- RUQ- Morison’s pouch
- LUQ- Peri-splenic view
- Pelvic view- Suprapubic
- Cardiac view
Free fluid in morisons pouch
Between liver and kidney
Perisplenic view
look between spleed and kidney
Pop during nerve blocks means what?
Needle passing through nerve sheath
Indications for gastric ultrasound (3)
-Lack of adherence to fasting instructions
-Unclear fasting history
-Potential delay in gastric emptying
Testing for NPO
<1.5 ml/kg = unlikely to have enough to have enough to worry about with aspiration
> 1.5 ml/kg and solid food on ultrasound = potential aspiration = RSI, wait to do the case,
Normal stomach on ultrasound looks like a ______
bullseye
High depth
too far away
Low depth
too close
Low depth
too close
High depth
too far away
