Download - Introduction to procedural ultrasound
Introduction toProcedural Ultrasound
Richard Hay
Procedural UltrasoundAim
Provide an overview of uses and techniquesWhyWhenHow
Advantages and disadvantagesBasic tips
Ultrasound Guided Procedures
Vascular accessCentral, Peripheral, Arterial
AspirationThoracocentesisParacentesisPericardiocentesisJoint aspirationSupra-pubic aspiration
Foreign body detection and removalNerve blocks
Why use Ultrasound for Procedures
Allows visualisation of anatomy prior to an invasive procedureDetect abnormal anatomyIdentify interposed structures
Better localisation of targetPrevent invasive procedure being attempted when
not indicated
Basic Ultrasound Knowledge for Learning Procedural Ultrasound
Choice of probeField of viewFrequency
The ultrasound beamSlice thickness and beam width
The ultrasound imageFluid is blackSoft tissues are greyAir and metal hyperechoic and cause
reverberationBone and stones cause shadowing
Basic Ultrasound Knowledge for Learning Procedural Ultrasound
The ultrasound imageWhat the needle looks like
Transverse Comet tail artifact Beam width artifact
Longitudinal Reverberation artifact
Size and depth measurement
Procedural TechniquesMethods
Indirect approachMark the spot
Direct approachReal time
Transverse (out of plane) Longitudinal (in plane)
Procedural TechniquesIndirect approach
Best forLarge static targets not too far away
Ascites Pleural effusion
Small superficial targets
Indirect approachTechnique
Locate target with US and identify best site for skin entryMeasure size and depthObserve for changes with respiration
Note midpoint and axial direction of transducerRemove transducer and mark skinPerform procedure
Indirect approachAdvantages
QuickEasy
Less coordination requiredLess experience required
No requirement for sterile transducer cover
Indirect approachDisadvantages
Not under direct visionNot good for small distant targetsPatient must not move between marking and
procedure
Procedural TechniquesDirect method
Needle is advanced under direct US visionTwo different approaches
Transverse Target in transverse section in center of image Needle approach is perpendicular to the scan plane
Transverse Approach
Procedural TechniquesDirect method
Needle is advanced under direct US visionTwo 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
Longitudinal Approach
Transverse approachIndications
Two or more parallel structures that appear similar when seen in longitudinal section
Not enough room for longitudinal approach
Transverse approachTechnique
Target in center of US imageNote 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
targetJiggle needle to move soft tissuesBeware not to advance needle beyond the scan
plane
Transverse approachAdvantages
Can see and avoid structures either side of the target
Can use a steeper angle of approachLess space at anatomical site required
Transverse approachDisadvantages
Needle harder to see in cross sectionOften rely on just the tissue movementDepth of needle difficult to assessSterile transducer cover required
Longitudinal approachIndications
Small targets requiring precise needle placementPeripheral vascular accessNerve blocksBiopsy
Longitudinal approachTechnique
Identify target in transverse then go to longitudinal viewNote depth of targetConsider needle trajectory and desired target
entry pointNeedle in line with midpoint of long axis of
transducerSlowly advance needle under direct vision
Angle corrections required to keep needle in line with scan plane
Longitudinal approachAdvantages
Better localisation of needleVisually striking
Watch needle all the way to the targetCan see structures deep and superficial to the target
Longitudinal approachDisadvantages
Difficult to line up three objectsUS beam, needle, targetRequires more
Coordination Practice
Cannot see structures either side of targetTwo adjacent parallel structures can look similar
Easy to slip from one to the other
Longitudinal approachDisadvantages
Difficult to line up three objectsUS beam, needle, targetRequires more
Coordination Practice
Cannot see structures either side of targetTwo adjacent parallel structures can look similar
Easy to slip from one to the otherMore space required at anatomical site
Shallow approach angleTransducer longitudinal
Procedural UltrasoundGeneral Comments
PositioningEnsure patient and operator comfortable
Line upPatient, target and transducer, screen
Watch the screen not your hands
Procedural UltrasoundGeneral Comments
PositioningEnsure patient and operator comfortable
Line upPatient, target and transducer, screen
Watch the screen not your handsUse the transducer to find the needleMake sure local anaesthetic is free of air
Procedural UltrasoundGeneral Comments
Vein vs arteryVeins
Thin walls, compress, respiratory variation, valsalva, triple pulsation
Arteries Round, thicker wall, single pulsation
Procedural UltrasoundGeneral Comments
Vein vs arteryVeins
Thin walls, compress, respiratory variation, valsalva, triple pulsation
Arteries Round, thicker wall, single pulsation
NervesView in transverseNeedle along scan plane
Procedural UltrasoundSummary
Ultrasound is useful for many proceduresImproved safety and successBasic ultrasound knowledge requiredA number of different techniques
Suit different circumstancesLearned skill
Practice