Sauter - Ultrasoundppt
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Transcript of Sauter - Ultrasoundppt
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7/29/2019 Sauter - Ultrasoundppt
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A. R. SauterRikshospitalet University Hospital
Ultrasound -
Theoretical and practical background
SOundNavigation And Ranging
Ultrasound image generation anddevice operations
Technical principles
20Hz 20kHz 200MHz
Infra-sound Ultrasound
Audiblesound
1-17MHzMedica
ultrasound
+ -electrical energy
electrical energy
Piezoelectric effect
Velocity (depending on the density):
Impedance:product of density and velocity
air 330 m/s
water 1450 m/s
fat 1450 1462-1473 m/s
muscle 1580 m/s
bone 4080 m/s
Technical principles
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Differences in impedance (interface)give reflections
Strong differences in impedancegive strong reflections
hyperechoic
Small differences in impedance givetransmission of the US beamhypoechoic
Technical principlesAcoustic coupling medium
Transducers Transducers
! Frequeny
" Frequeny
! Resolution
" Resolution
" Penetration
! Penetration
Transducers
Axial resolution
Lateral resolution
Spatial resolution
Resolution
Axial resolution
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Lateral resolution TGC - Time Gain Compensation
AT
TENUATION
Reflection
Scatter
Refraction
Absorption
ENERGY
DISTANCE
TGC - Time Gain Compensation
ENERGY
DISTANCE
ATTEN
UATION
Amplified signal
TGC - Time Gain Compensation
TGC - Time Gain Compensation
Near
Far
Overall
Time gain control
Focus and Depth
Sites 2008
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Doppler sonography Doppler sonography
increased frequency
decreased frequency
Practical aspects
Ultrasound imaging
pressure
alignment
rotation
tilting
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Ultrasound imaging
Short axis Long axis
Ultrasound imaging
In-plane Out-of-plane
In-plane needle insertion
Out-of-plane needle insertion
short axis / in-plane
short axis / out-of-plane
long axis / in-plane
long axis / out-of-plane
Ultrasound imaging
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Ultrasound imaging
Visualization of nerves:
Visualization of nerves:-honeycomb structure- hypoechoic or anechoic
Bigeleisen 2006
Ultrasound imaging
Visualization of local anesthetics:
Pitfalls and artifacts
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Characterizing novice behavior associated with learningultrasound-guided peripheral regional anesthesia.Sites BD, Spence BC, Gallagher JD, Wiley CW, Bertrand ML, Blike GT.Reg Anesth Pain Med 2007;32:107-15.
Video documentation of USG nerve blocksperformed by 6 anesthesia residents
398 committed errors in 520 blocks
Characterizing novice behavior associated with learningultrasound-guided peripheral regional anesthesia.Sites BD, Spence BC, Gallagher JD, Wiley CW, Bertrand ML, Blike GT.Reg Anesth Pain Med 2007;32:107-15.
1) failure to recognize the maldistributionof localanesthesia
2) failure to recognize the location of the needletip before injection
3) fatigue
4) failure to correctly correlate the sidedness of the
patient with the sidedness of the ultrasoundimage
5) poor choice of needle-insertion site and angle with
respect to the probe preventing accurateneedlevisualization.
Intravascular needle placement Intraneural needle placement
Pneumothorax
Koscielniak-Nielsen 2008
Ultrasound-guided PNB
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Sauter 2010 - Ultrasound