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Much Ado About Ultrasound


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

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

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

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

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

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

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

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

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

Nerve Stimulator Technique
  • Weaknesses
  • Multiple injections needed for optimal success
  • 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

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

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

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

Visualize the Needle
Interscalene block placement
Visualize the Local Anesthetic
Interscalene block placement
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

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)

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

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

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

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

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

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
  • Comparison of speed of execution and quality of

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

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

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

  • 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

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

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

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

Any Questions?
  • 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
  • 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
  • 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
  • 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