Regional anesthesia and pain medicine
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Reg Anesth Pain Med · Jul 2009
Randomized Controlled Trial Comparative StudyA randomized, observer-blinded determination of the median effective volume of local anesthetic required to anesthetize the sciatic nerve in the popliteal fossa for stimulating and nonstimulating perineural catheters.
Stimulating perineural catheters are developed to overcome technical problems of nonstimulating catheters, but their efficacy remains controversial. However, no volume-response study has compared success rates between stimulating and nonstimulating catheters. This study of stimulating versus nonstimulating catheters compares the minimal effective volume required to successfully block the sciatic nerve in 50% of patients scheduled for unilateral hallux valgus repair. ⋯ Stimulating popliteal catheters dramatically decrease the volume required to block the sciatic nerve in 50% of patients, compared with nonstimulating catheters.
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Reg Anesth Pain Med · Jul 2009
Multicenter StudyVarious possible positions of conventional catheters around the femoral nerve revealed by neurostimulation.
In continuous femoral nerve blocks, the various perineural positions of the tip of a conventional catheter and their clinical implication are not completely known.We used stimulating catheters to explore the relationship of catheter tip to nerve. ⋯ The effectiveness of a continuous femoral block depends on neurostimulation characteristics, which likely correspond to various possible catheter tip positions. Conventional catheters provide no information on this issue. These results suggest that better VAS scores are attainable by placing catheters with neurostimulation guidance.
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Reg Anesth Pain Med · Jul 2009
Calcium chloride prolongs the effects of lidocaine and bupivacaine in rat sciatic nerve.
Elevated extracellular calcium ion has been shown to shift the voltage dependence of Na+- and K+-ion channels rightward, making the nerve less excitable. We hypothesized that calcium chloride (CaCl2) when used as an adjuvant prolongs and intensifies the block by local anesthetics (LAs). We investigated the effects of LAs combined with calcium in rat sciatic nerve blockade and in cultured rat GH3 cells expressing Na+ channels. Furthermore, we tested for histologic changes due to CaCl2. ⋯ The mechanism of prolonged nerve block of CaCl2 coadministered with LAs seems to be a raised threshold for nerve excitation. Major histopathologic changes at higher concentrations of CaCl2 are evident, and therefore, clinical application as an adjuvant to LAs seems unlikely.
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Reg Anesth Pain Med · Jul 2009
Randomized Controlled Trial Comparative StudyComparison of 3 intensities of stimulation threshold for brachial plexus blocks at the midhumeral level: a prospective, double-blind, randomized study.
We conducted this prospective randomized study to compare the success rate and the onset time between 3 intensities of stimulation threshold (<0.5, 0.5-0.64, and 0.65-0.8 mA) when using a peripheral nerve stimulation at the midhumeral level. ⋯ We conclude that intensity of stimulation influenced onset time and success rate.