Regional anesthesia and pain medicine
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Reg Anesth Pain Med · May 2009
Minimal local anesthetic volume for peripheral nerve block: a new ultrasound-guided, nerve dimension-based method.
Nerve blocks using local anesthetics are widely used. High volumes are usually injected, which may predispose patients to associated adverse events. Introduction of ultrasound guidance facilitates the reduction of volume, but the minimal effective volume is unknown. In this study, we estimated the 50% effective dose (ED50) and 95% effective dose (ED95) volume of 1% mepivacaine relative to the cross-sectional area of the nerve for an adequate sensory block. ⋯ Based on the ultrasound measured cross-sectional area and using ultrasound guidance, a mean volume of 0.7 mL represents the ED95 dose of 1% mepivacaine to block the ulnar nerve at the proximal forearm.
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Reg Anesth Pain Med · May 2009
Clinical TrialMinimum effective volume of local anesthetic for ultrasound-guided supraclavicular brachial plexus block.
The aim of this study was to determine the minimum effective anesthetic volume required to produce an effective supraclavicular block for surgical anesthesia using an ultrasound (US)-guided technique. ⋯ In this study, the minimum volume required for US-guided supraclavicular block in 50% of patients was 23 mL, and in 95% of patients was 42 mL. Under the present study conditions, the calculated volume of LA required for US-guided supraclavicular block does not seem to differ from the conventionally recommended volume required for supraclavicular blocks using non-US-based nerve localization techniques.
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Reg Anesth Pain Med · May 2009
Ultrasound-guided obturator nerve block: an interfascial injection approach without nerve stimulation.
For knee surgery, obturator nerve block (ONB) has been shown to enhance postoperative analgesia provided by femoral block. Current techniques for obturator block use surface landmarks or ultrasound guidance (USG) with nerve stimulation. This preliminary observational study evaluated the success of an ultrasound-guided ONB without the additional use of nerve stimulation. ⋯ Obturator nerve block using USG to achieve interfascial injection without nerve stimulation had success similar to that reported in studies using nerve stimulation.
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Reg Anesth Pain Med · May 2009
Structural injury to the human sciatic nerve after intraneural needle insertion.
Recent clinical reports suggest that intraneural needle placement may not always lead to neurologic injury. To explain the absence of neurologic complications in these reports, we studied the risk and extent of nerve injury after intentional needle-nerve placement in a cryopreserved human sciatic nerve. ⋯ Our findings suggest that intraneural needle insertion may more commonly result in interfascicular rather than intrafascicular needle placement.
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Reg Anesth Pain Med · May 2009
Evaluation of the longus colli muscle in relation to stellate ganglion block.
The longus colli (LC) muscle is an important structure of the anterior cervical spine and has a critical role in stellate ganglion block. This technique involves withdrawing the needle to locate its port for injection above the anterior surface of the LC muscle; however, its exact thickness at the C5, C6, and C7 levels has not been measured. The aim of this anatomic and magnetic resonance-supported study was to evaluate the thickness of the LC muscle at these levels from the anterior tubercle of each vertebra toward the vertebral body at 5-, 10-, and 15-mm distances to provide precise anatomic data for stellate ganglion block. ⋯ We found a highly variable thickness of the LC muscle in anatomic and imaging studies, which may lead to negative block results.