E4- Ultrasound Flashcards
When was ultrasound first used in medicine?
What was it popular in?
Why was it popular?
- 1950’s
- obstetrics
- no ionizing radiation.
- US is described as seeing using _____________.
- Examples in nature?
- Military?
- sound waves
- bats + dolphins
- submarines
Advantages of ultrasound.
- Identify anatomical structures
1. * Relationship of the needle to tissues
1. * Increases accuracy
1. * “See” spread of LA
1. * May decrease time performing pain blocks/assessments
1. * May decrease complications
Ultrasound waves travel between these Mhz.
- 2-20 Mhz
Travels differently w/ different structures
What is the range of audible sounds?
- 20-20,000 Hz
- What 3 can ultrasound waves do when they encounter a surface?
sound waves are ______ back to crystals + create impulse on computer
- Transmit through the surface
- Reflect on the surface
- Something in between
Reflected
What is the result when ultrasound waves are transmitted through fluid?
- No signal
- Anechoic
- Dark
What is the result when ultrasound waves are reflected on bones/stones?
- Lots of signals
- Hyperechoic
- Bright
What results when ultrasound waves encounter soft tissue, muscles, and fat?
- Iso/hypoechoic
- Shades of grade
Which picture represents a solid?
Which picture represents fluid?
- Picture A: Solid
- Picture B: Fluid
What is inside the transducer’s head that changes shape with an electric impulse?
- Piezo Electric Crystals
Starts to vibrate … generate sound wave
What are the three types of transducers used in POCUS?
- Linear Array
- Curve Array
- Phased Array
Describe a Linear Array
- High frequency (7-15 MHz)
- Better resolution
- superficial depth
- IV, CVL, art line
Describe a Curve Array
- Low frequency (2-5 MHz)
- Poorer resolution
- Great for deeper tissue
- kidney, liver, spleen, bladder, GI
Describe a Phased Array
- Lowest frequency (1-3 MHz)
- Useful for echocardiography
- axial plane?
- coronal plane?
- sagittal plane?
- top : bottom
- front : back
- Left : right
Static vs Dynamic Approach for Ultrasound
Static: Identifying the target vessel, assessing the patency, marking an appropriate insertion site, and cannulating blindly.
Dynamic: Performing the procedure in real-time and viewing the needle puncturing the vessel wall.
Tips and Tricks for using Ultrasound.
- Proper Ergonomics
- Use Conductive gel
- Hold probe like pencil
- Focus using gain + depth
What is gain?
- brightness signal quality
- adjusted with a knob.
- Twist the knob back + forth until… fluid = black + soft tissue = mid-grey
What is depth?
- 2 up/down buttons
- shown in cm on screen
- start at highest depther + get object in middle of screen
In-plane vs. Out-of-plane refers to the relationship of ______ to the ultrasound plane.
long/short axis refers to ___________ and should always be ______________ axis for procedures
- needle
- vessel ,, long
What is the advantage of in-plane ultrasound?
Disadvantage?
- Advantage: See the whole needle
- Disadvantage: Easy to be off plane
What is the advantage of out-of-plane ultrasound?
Disadvantage?
- Advantage: The needle is positioned directly under the plane of an ultrasound
- Disadvantage: Unclear where tip of the needle is
What do you look for to determine that your guidewire is in the vessel’s lumen?
- Vanishing Sign
Common anesthesia use for ultrasound.
- Guided IV Access
- Focused Assessment with Sonography for Trauma (FAST)
- Ultrasound-guided Nerve Blocks
- Gastric Ultrasound
What are the indications for using USG IV Access?
- History of difficult cannulation
- Multiple failed attempts
- Best to use a linear probe
- if the patient is obese = use the curve probe
What are the contraindications for using USG IV Access?
- Does not substitute for IO access in life-threatening situations
- what does FAST stand for?
- Indications to use a FAST.
- contraindications?
- focused assessment w/ sonography for trauma
- To rule out free fluid in the abdomen + pericardium
- none
What probe is used for a FAST?
- Curvilinear probe
What are the assessment order for FAST?
- (1) RUQ = Morison’s pouch
- (2) LUQ = Peri-splenic view
- (3) Pelvic view = Suprapubic
- (4) Cardiac view
PNB
- What should be done to plan for PNB route?
- When performing a USG peripheral nerve block, what can be done to maintain parallel alignment with the US monitor?
- await for _______________ .
- verify nerve doesn’t __________ with needle
- pre-block scan
- Heeling
- fascial “pop”
- move
What are the indications for the gastric US?
- Lack of adherence to fasting instructions
- Unclear fasting history
- Potential delay in gastric emptying
Grade the Antrum
- Grade 0 Antrum: Empty Stomach
- Bull’s Eye
NPO
Grade the Antrum
- Grade 1 Antrum: < 1.5 ml/kg
- Aspiration Unlikely
Clear liquids
Grade the Antrum
- Grade 2 Antrum: > 1.5 ml/kg
- Solid Food
- High Risk of Aspiration
solid food
What does NPO look like on US?
o Antrum = empty
o Small
o “bullseye sign”
What does clear liquids look like on US?
o Rounder, more distended
Thin walls
o “Starry night” – esp w/ air bubbles
o Peristalsis starts
What does milk/thick fluids look like on US?
o Thinner walls
o Increased echogenicity
What does solid food look like on US?
o Hyperechoic - bright
