4. Why use Ultrasound for Procedures
Allows visualisation of anatomy prior to an invasive
procedure
Detect abnormal anatomy
Identify interposed structures
Better localisation of target
Prevent invasive procedure being attempted when
not indicated
5.
6. Basic Ultrasound Knowledge for Learning
Procedural Ultrasound
Choice of probe
Field of view
Frequency
The ultrasound beam
Slice thickness and beam width
The ultrasound image
Fluid is black
Soft tissues are grey
Air and metal hyperechoic and cause reverberation
Bone and stones cause shadowing
7. Basic Ultrasound Knowledge for Learning
Procedural Ultrasound
The ultrasound image
What the needle looks like
Transverse
Comet tail artifact
Beam width artifact
Longitudinal
Reverberation artifact
Size and depth measurement
11. Indirect approach
Technique
Locate target with US and identify best site for skin
entry
Measure size and depth
Observe for changes with respiration
Note midpoint and axial direction of transducer
Remove transducer and mark skin
Perform procedure
14. Procedural Techniques
Direct method
Needle is advanced under direct US vision
Two different approaches
Transverse
Target in transverse section in center of image
Needle approach is perpendicular to the scan plane
16. Procedural Techniques
Direct method
Needle is advanced under direct US vision
Two different approaches
Transverse
Target in transverse section in center of image
Needle approach is perpendicular to the scan plane
Longitudinal
Target in longitudinal section across image
Needle approach is along the scan plane
18. Transverse approach
Indications
Two or more parallel structures that appear similar
when seen in longitudinal section
Not enough room for longitudinal approach
19. Transverse approach
Technique
Target in center of US image
Note depth of target
Needle in line with midpoint of transducer a few
centimeters away
Slowly advance needle and watch tip by:
Fanning transducer toward needle and back to target
Jiggle needle to move soft tissues
Beware not to advance needle beyond the scan plane
20.
21. Transverse approach
Advantages
Can see and avoid structures either side of the
target
Can use a steeper angle of approach
Less space at anatomical site required
24. Longitudinal approach
Technique
Identify target in transverse then go to longitudinal
view
Note depth of target
Consider needle trajectory and desired target entry
point
Needle in line with midpoint of long axis of
transducer
Slowly advance needle under direct vision
Angle corrections required to keep needle in line with
scan plane
27. Longitudinal approach
Disadvantages
Difficult to line up three objects
US beam, needle, target
Requires more
Coordination
Practice
Cannot see structures either side of target
Two adjacent parallel structures can look similar
Easy to slip from one to the other
28.
29. Longitudinal approach
Disadvantages
Difficult to line up three objects
US beam, needle, target
Requires more
Coordination
Practice
Cannot see structures either side of target
Two adjacent parallel structures can look similar
Easy to slip from one to the other
More space required at anatomical site
Shallow approach angle
Transducer longitudinal
32. Procedural Ultrasound
General Comments
Positioning
Ensure patient and operator comfortable
Line up
Patient, target and transducer, screen
Watch the screen not your hands
Use the transducer to find the needle
Make sure local anaesthetic is free of air
33. Procedural Ultrasound
General Comments
Vein vs artery
Veins
Thin walls, compress, respiratory variation, valsalva, triple
pulsation
Arteries
Round, thicker wall, single pulsation
34.
35.
36. Procedural Ultrasound
General Comments
Vein vs artery
Veins
Thin walls, compress, respiratory variation, valsalva, triple
pulsation
Arteries
Round, thicker wall, single pulsation
Nerves
View in transverse
Needle along scan plane
37. Procedural Ultrasound
Summary
Ultrasound is useful for many procedures
Improved safety and success
Basic ultrasound knowledge required
A number of different techniques
Suit different circumstances
Learned skill
Practice
Editor's Notes
Not performing procedure “blind” using landmark technique
Detect abnormal anatomy
For example the IJV is not lateral to the common carotid artery in approximately 15-20% of patients.
US use for central venous access has been shown to:
Reduce complications
Reduce the number of attempts
Reduce time to success
Considered to be the standard of care in central vascular access.
For example tumour mass causing white of CXR rather than pleural effusion.
In general:
Linear probe for superficial structures – vascular, nerve, FB, abscess
Curved probe for deeper structures – ascites, pleural effusion
Measure skin to target and depth of target.
Needle direction corresponds to noted axial direction of transducer.
For example
Femoral vessels
Neck vessels
Identify bright echo of needle
Steeper angle of approach
Less space required
Can use use a shorter needle
Less space:
Transducer transverse
Approach angle
Depth of needle:
Can go beyond the scan plane and hit deeper structures
Needle in line with transducer
Needle will only be visible when a few mm under the probe
Two parallel structure:
For example an artery and adjacent vein
Line up
Veins compress
A lot of pressure required to compress arteries