Introduction to POCUS Flashcards
Pros of Ultrasound
- Used for diagnostic and procedural purposes
- No ionizing radiation
- Noninvasive
- Portable
- Relatively easy to use
- Quick
- Immediate feedback
- Inexpensive examinations
- Easily repeated at the bedside, thereby enhancing clinicians ability to perform serial reassessments of patients
- Improve diagnostic accuracy, decreases overall cost of care and decreases time to diagnosis
Chest and Abdominal Application of POCUS
- FAST SCAN
- Undifferentiated shock
- Cardiac/lung/aorta/GB/Renal/Urinary retention
Chest and Abdominal Applications of POCUS
- FAST SCAN
- Undifferentiated shock
- Cardiac/lung/aorta/GB/renal/urinary retention
MSK Applications of POCUS
- Abscess vs induration
- Joint evaluation
- Fractures
- Assess ligaments and tendons
- Foreign bodies
Ocular Application of POCUS
Retinal detachment and hemorrhage
Procedural Application of POCUS
- Central lines
- Peripheral IVs
OB/GYN Application of POCUS
- Fetal well-being/fetal heart tones
- R/o ectopic pregnancy
Frequency
- number of times per second a wave is repeated
- expressed as Hertz (Hz)
Wavelength
Distance the wave travels in a single cycle
Frequency and Wavelength are ____ related
Inversely
Relationship of Wavelength and Frequency
- higher the frequency the shorter the wavelength
- high-frequency sound waves have short wavelengths (don’t penetrate deeply into tissue)
- Lower frequency sound waves have longer wavelengths (can penetrate deeply into tissue)
- higher the frequency the better the resolution
Linear (Vascular) Probe
- higher frequencies and resolution
- for superficial scanning and procedural guidance
- preserved lateral resolution
Sector or Phased Array (Cardiac) Probe
- lower frequencies
- small footprint for intercostal scanning
- high frame rates
Curvilinear (Curved Array or Abdominal) Probe
- lowest frequency
- large field of view
- large footprint
B-Mode
- “brightness” mode aka “grey scale”
- two-dimensional black and white image with shades of gray in between to indicate the strength of the echo
- default view on most US machines
- most US images are in this mode
M-Mode
- “motion” mode
- draws a line on the screen and shows echo profile of every structure along that line (y-axis) over time (x-axis)
- used to demonstrate or measure movement over time in a still image
Echogenicity
- ability of a structure to reflect sound waves or echoes
- anechoic vs hypoechoic vs hyperechoic
Anechoic
- complete absence of returning sound waves
- appears black (ex. fluid)
Hypoechoic
structures that have very echoes and appear darker than the surrounding tissue
Hyperechoic
- echogenic structures
- appear brighter than the surrounding tissue
Acoustic Shadowing
- common artifact
- occurs when the sound waves encounter a highly reflective surface
- hypoechoic or anechoic area appears deep to the structure
- occurs because very few sound waves can get behind or around the structure
- Ex. gallstones
Posterior Acoustic Enhancement
- common artifact
- occurs deep to an anechoic structure
- there is an increase in echogenicity posterior to an anechoic structure because the sound waves lose very little energy traveling through a fluid filled structure
- Ex. bladder (area behind the structure appears very echogenic or bright)
Edge Artifact
- sound is refracted (bent) by a structure in parallel with the US beam and does not return to the probe, resulting in the appearance of a shadow behind the surface
- arrowheads show edge artifact from the wall of the gallbladder
- generally seen when imaging fluid filled structures like the gallbladder or vessels in transverse imaging
Mirror Artifact
- you see the “mirror image” of the structure being imaged
- it will be distal in relation to the probe
- generally appears at the bottom or periphery of the screen
- highly reflective surfaces cause the machine to display an artifactual image of the reflection of an object
Reverberation Artifact
- typically seen with line placement
- multiple intermittent lines “echoes” running parallel to the actual needle
Gain
- brightness of the US image
- the brighter the image the higher the gain and vice versa
- adjust this by swiping left or right
Longitudinal scanning is with the probe marker:
toward the head
Transverse scanning is with the probe marker:
facing the patient’s right so that the image will look similar to the orientation of a CT scan
— exception is cardiac where the screen marker is on the left
Sliding Technique
Move the probe along the skin without changing angles
Rocking (Heel-Toe) Technique
Tilt the probe along the axis of the indicator
Fanning (Sweeping) Technique
Tilt the probe perpendicular to the axis of the indicator
Rotating Technique
Rotate the probe above the axis of the cord without tilting
ALARA (As Low As Reasonably Achievable Exposure) Ultrasound
- concept comes from the use of ionizing radiation in the diagnostic imaging of x-rays
- never been shown to harm humans
- safe for fetal imaging at all gestational ages as well as adults
How do you adjust depth?
by swiping up and down with the probe
