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Much Ado About Ultrasound

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Much Ado About Ultrasound John Wolfe, MD CA-2 Resident June 6, 2007 Overview Rationale for performing peripheral nerve blocks Nerve stimulator technique Ultrasound ... – PowerPoint PPT presentation

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Title: Much Ado About Ultrasound


1
Much Ado About Ultrasound
  • John Wolfe, MD
  • CA-2 Resident
  • June 6, 2007

2
Overview
  • Rationale for performing peripheral nerve blocks
  • Nerve stimulator technique
  • Ultrasound technique
  • Comparisons of the techniques
  • Conclusions

3
Advantages of Nerve Blocks
  • Improved immediate analgesia post-op
  • Reduced side effects of general anesthesia
  • Reduced side effects of analgesics
  • Provision for continued post-op analgesia with
    catheter placement
  • Improved patient satisfaction
  • More rapid and effective rehabilitation
  • More rapid recovery of postoperative cognitive
    function

4
Disadvantages of Nerve Blocks
  • Surgeons concerns
  • Time for block placement
  • Time for block setup
  • Patients concerns
  • Anxiety
  • Needle punctures and manipulation
  • Movement of fractured extremities

5
Disadvantages of Nerve Blocks
  • Anesthesiologists concerns
  • Failed blocks
  • Complications
  • Nerve damage
  • Toxicity
  • Infection
  • Hematoma

6
Nerve Stimulator Technique
  • Insulated needle advanced based on surface
    landmarks
  • Variable current applied through the needle
  • Motor responses sought in nerve territories that
    correspond to the surgical site

7
Nerve Stimulator Technique
  • Strengths
  • Functional confirmation of proximity of the
    needle to the nerve
  • Small, inexpensive, simple equipment

8
Nerve Stimulator Technique
  • Weaknesses
  • Blind technique
  • Variable anatomy
  • Variability of thresholds for motor responses
  • Pain with movement of injured extremities

9
Nerve Stimulator Technique
  • Weaknesses
  • Multiple injections needed for optimal success
    rates
  • Studies demonstrate this at the axillary,
    interscalene, and infraclavicular locations
  • Likely due to inaccurate placement or spread of
    the anesthetic
  • Inability to see other nearby structures

10
Addition of Ultrasound
  • Ultrasound imaging allows localization of the
    nerves
  • Other structures are also visualized
  • Blood vessels
  • Pleura
  • Bone
  • Muscle

11
What Does Ultrasound Do?
  • Piezoelectric crystals on the transducer vibrate
    in response to an electrical field
  • The vibrations (ultrasound waves) reflect,
    refract, and scatter when they encounter
    structures of different acoustic impedance
  • Reflected vibrations are converted back to
    electrical energy by the transducer
  • Software reconstructs an image

12
What Does Ultrasound Do?
  • Systems vary in transducer size and shape
  • Higher frequency better resolution but poorer
    penetration
  • Lower frequency better penetration but poorer
    resolution
  • Doppler analysis allows identification of
    vascular structures

13
Interscalene
14
Supraclavicular
15
Infraclavicular
16
Axillary
17
Visualize the Needle
Interscalene block placement
18
Visualize the Local Anesthetic
Interscalene block placement
19
Ultrasound Guidance
  • Advantages
  • Visual localization of nerves
  • Visualization of hazards
  • Visualization of local anesthetic spread
  • Avoidance of painful muscle contractions
  • Disadvantages
  • Equipment cost, size, and complexity
  • Learning curve

20
Is Ultrasound Guidance Better?
  • Some studies have shown improvements in time to
    perform the block and onset time
  • Marhofer et al 1998
  • Ultrasound guidance for three in one block
  • 50 faster block onset time
  • Williams et al 2003
  • RCT comparing US vs. NS supraclavicular blocks
  • US blocks were faster (5 vs. 10 min)

21
Is Ultrasound Guidance Better?
  • Soeding et al 2005
  • Comparison of US guidance vs. surface landmarks
    for interscalene and axillary blocks
  • Faster onset times
  • Schwemmer et al 2005
  • US vs. NS axillary blocks
  • Surgery could proceed 15 minutes faster in the US
    group

22
Is Ultrasound Guidance Better?
  • Results have not been uniform
  • The best results have been seen if
  • Needle redirection is used to spread the local
    anesthetic around the neural structure
  • The control NS group was single-injection
  • Outcome studies have been small in scale

23
Are They Additive Techniques?
  • Nerve stimulation gives functional confirmation
  • Ultrasound gives visual confirmation
  • Is the block best done with both?

24
Studies of US NS Blocks
  • Van Geffen and Gielen 2006
  • Sciatic nerve block catheter placement in
    children
  • Minimal current for muscle contraction varied
    widely among patients
  • Visualization of local anesthetic spread
    predicted successful blocks

25
Studies of US NS Blocks
  • Beach et al 2006
  • Supraclavicular blocks with both US and NS
  • For ultrasound guided blocks, positive nerve
    stimulation did not increase the success rate
  • Nerve stimulation had a high false negative rate

26
Studies of US NS Blocks
  • Dingemans et al 5/2007
  • 72 patients received infraclavicular blocks
  • Patients either had blocks with ultrasound
    guidance alone or ultrasound plus nerve
    stimulation
  • Comparison of speed of execution and quality of
    block

27
Studies of US NS Blocks
  • Injection Techniques
  • Ultrasound only
  • Goal was a U-shaped distribution posterior and to
    either side of the axillary artery
  • 1, 2, or 3 injections (most were 1 injection)
  • Ultrasound plus nervestim
  • Distal motor response at 0.3 to 0.6 mA
  • Single injection

28
Studies of US NS Blocks
  • Results
  • Faster block placement in the US only group
  • Ultrasound only 3.1 1.6 min
  • Ultrasound nerve stimulator 5.2 4.7 min

29
Studies of US NS Blocks
  • Better block quality in US only group
  • Percent of patients with sensory block in 4 major
    nerve territories
  • Ultrasound only 86
  • Ultrasound nerve stimulator 57
  • Need for block supplementation
  • Ultrasound only 8
  • Ultrasound nerve stimulator 26

30
Conclusions
  • Multi-injection, ultrasound-guided nerve blockade
    is faster and better than single-injection nerve
    stimulator-guided nerve blockade
  • Multi-injection, ultrasound-guided nerve blockade
    may be faster and better than multi-injection
    nerve stimulator-guided nerve blockade
  • Adding nerve stimulation to ultrasound guided
    blocks may be more hindrance than help

31
Study Limitations
  • Studies are small and not uniform in design
  • Results are not uniform
  • Proving a safety benefit is difficult

32
Practical Limitations
  • Learning curve for ultrasound
  • Equipment cost
  • Poor images (e.g. body habitus) hinder US block
    placement
  • Need for training with the nerve stimulator in
    residency

33
Future Directions
  • Ultrasound equipment will continue to get better,
    smaller, and cheaper
  • Ultrasound block techniques will be refined
  • Outcomes and performance data will accumulate

34
Any Questions?
35
References
  • Dingemans, Emmanuel MD Williams, Stephan R.
    MD, PhD Arcand, Genevieve MD, FRCPC
    Chouinard, Philippe MD, FRCPC Harris, Patrick
    MD, FRCSC Ruel, Monique RN Girard, Francois
    MD, FRCPC Neurostimulation in Ultrasound-Guided
    Infraclavicular Block A Prospective Randomized
    Trial. Anesthesia Analgesia.
    104(5)1275-1280, May 2007.
  • Rodriguez J. Barcena M. Taboada-Muniz M.
    Lagunilla J. Alvarez J. A comparison of single
    versus multiple injections on the extent of
    anesthesia with coracoid infraclavicular brachial
    plexus block. Anesthesia Analgesia.
    99(4)1225-30, 2004 Oct.
  • Horlocker TT. Wedel DJ. Ultrasound-guided
    regional anesthesia in search of the holy grail.
    Anesthesia Analgesia. 104(5)1009-11, 2007
    May
  • Beach ML. Sites BD. Gallagher JD. Use of a nerve
    stimulator does not improve the efficacy of
    ultrasound-guided supraclavicular nerve blocks.
    Journal of Clinical Anesthesia. 18(8)580-4, 2006
    Dec.
  • Sites BD. Brull R. Ultrasound guidance in
    peripheral regional anesthesia philosophy,
    evidence-based medicine, and techniques. Current
    Opinion in Anaesthesiology. 19(6)630-9, 2006
    Dec.
  • Marhofer P. Sitzwohl C. Greher M. Kapral S.
    Ultrasound guidance for infraclavicular brachial
    plexus anaesthesia in children. Anaesthesia.
    59(7)642-6, 2004 Jul.
  • Marhofer, Peter MD Chan, Vincent W. S. MD,
    Ultrasound-Guided Regional Anesthesia Current
    Concepts and Future Trends. Anesthesia
    Analgesia. 104(5)1265-1269, May 2007.
  • Williams SR. Chouinard P. Arcand G. Harris P.
    Ruel M. Boudreault D. Girard F. Ultrasound
    guidance speeds execution and improves the
    quality of supraclavicular block. Anesthesia
    Analgesia. 97(5)1518-23, 2003 Nov.
  • Schwemmer U. Markus CK. Greim CA. Brederlau J.
    Roewer N. Ultrasound-guided anaesthesia of the
    axillary brachial plexus efficacy of multiple
    injection approach. Ultraschall in der Medizin.
    26(2)114-9, 2005 Apr.
  • Marhofer P. Schrogendorfer K. Wallner T. Koinig
    H. Mayer N. Kapral S. Ultrasonographic guidance
    reduces the amount of local anesthetic for 3-in-1
    blocks Regional Anesthesia Pain Medicine.
    23(6)584-8, 1998 Nov-Dec.
  • Soeding PE. Sha S. Royse CE. Marks P. Hoy G.
    Royse AG. A randomized trial of
    ultrasound-guided brachial plexus anaesthesia in
    upper limb surgery Anaesthesia Intensive
    Care. 33(6)719-25, 2005 Dec.
  • New York School of Regional Anesthesia website
    www.nysora.com
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