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Introduction to procedural ultrasound
This document provides an overview of using ultrasound for medical procedures. It discusses how ultrasound can be used to visualize anatomy, identify abnormal structures, and localize targets to improve safety and success of procedures. Two main techniques are described: indirect, where the target is located with ultrasound and then marked on the skin before proceeding; and direct, where the needle is advanced under real-time ultrasound guidance in either a transverse or longitudinal approach. Mastering basic ultrasound skills and choosing the appropriate technique for each procedure requires training and practice.
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Introduction to procedural ultrasound
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- 2. Procedural Ultrasound Aim Provide anoverview of uses and techniques Why When How Advantages and disadvantages Basic tips
- 3. Ultrasound Guided Procedures Vascularaccess Central, Peripheral, Arterial Aspiration Thoracocentesis Paracentesis Pericardiocentesis Joint aspiration Supra-pubic aspiration Foreign body detection and removal Nerve blocks
- 4. Why use Ultrasoundfor 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
- 6. Basic Ultrasound Knowledgefor 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 Knowledgefor 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
- 8. Procedural Techniques Methods Indirect approach Markthe spot Direct approach Real time Transverse (out of plane) Longitudinal (in plane)
- 9. Procedural Techniques Indirect approach Bestfor Large static targets not too far away Ascites Pleural effusion Small superficial targets
- 11. Indirect approach Technique Locate targetwith 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
- 12. Indirect approach Advantages Quick Easy Less coordinationrequired Less experience required No requirement for sterile transducer cover
- 13. Indirect approach Disadvantages Not underdirect vision Not good for small distant targets Patient must not move between marking and procedure
- 14. Procedural Techniques Direct method Needleis 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
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- 16. Procedural Techniques Direct method Needleis 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
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- 18. Transverse approach Indications Two ormore parallel structures that appear similar when seen in longitudinal section Not enough room for longitudinal approach
- 19. Transverse approach Technique Target incenter 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
- 21. Transverse approach Advantages Can seeand avoid structures either side of the target Can use a steeper angle of approach Less space at anatomical site required
- 22. Transverse approach Disadvantages Needle harderto see in cross section Often rely on just the tissue movement Depth of needle difficult to assess Sterile transducer cover required
- 23. Longitudinal approach Indications Small targetsrequiring precise needle placement Peripheral vascular access Nerve blocks Biopsy
- 24. Longitudinal approach Technique Identify targetin 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
- 26. Longitudinal approach Advantages Better localisationof needle Visually striking Watch needle all the way to the target Can see structures deep and superficial to the target
- 27. Longitudinal approach Disadvantages Difficult toline 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
- 29. Longitudinal approach Disadvantages Difficult toline 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
- 30. Procedural Ultrasound General Comments Positioning Ensurepatient and operator comfortable Line up Patient, target and transducer, screen Watch the screen not your hands
- 32. Procedural Ultrasound General Comments Positioning Ensurepatient 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 Veinvs artery Veins Thin walls, compress, respiratory variation, valsalva, triple pulsation Arteries Round, thicker wall, single pulsation
- 36. Procedural Ultrasound General Comments Veinvs 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 isuseful 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
- #5 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.
- #7 In general: Linear probe for superficial structures – vascular, nerve, FB, abscess Curved probe for deeper structures – ascites, pleural effusion
- #12 Measure skin to target and depth of target. Needle direction corresponds to noted axial direction of transducer.
- #19 For example Femoral vessels Neck vessels
- #20 Identify bright echo of needle
- #22 Steeper angle of approach Less space required Can use use a shorter needle Less space: Transducer transverse Approach angle
- #23 Depth of needle: Can go beyond the scan plane and hit deeper structures
- #25 Needle in line with transducer Needle will only be visible when a few mm under the probe
- #28 Two parallel structure: For example an artery and adjacent vein
- #31 Line up
- #34 Veins compress A lot of pressure required to compress arteries