Regional anesthesia and pain medicine
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Reg Anesth Pain Med · Jul 2007
Magnesium sulfate diminishes the effects of amide local anesthetics in rat sciatic-nerve block.
Magnesium sulfate (MgSO(4)) is well known as an antagonist of N-methyl-d-aspartate receptors and was used for intrathecal analgesia a century ago. However, the effects of MgSO(4) combined with local anesthetics (LAs) on peripheral nerves are unclear. We tested the hypothesis that MgSO(4) could be used as an adjuvant to prolong and intensify conduction block by amide-type LAs in a rat sciatic-nerve block model. Further, the mechanism of possible synergy between LAs and MgSO(4) was investigated in whole-cell mode patch-clamp experiments. ⋯ MgSO(4) coadministered with amide-type LAs shortened the duration of sciatic-nerve block in rats. Therefore, it does not seem to be useful as an adjuvant for peripheral-nerve block. The mechanism of this observed antagonism is unclear but appears to be independent of the action of LAs and MgSO(4) at the LA receptor within the Na(+) channel.
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Reg Anesth Pain Med · Jul 2007
Randomized Controlled TrialMotor blocking minimum local anesthetic concentrations of bupivacaine, levobupivacaine, and ropivacaine in labor.
Adequate comparison of blocking capabilities of local anesthetics should be done with some knowledge of their relative potencies. The objective of this clinical trial was to simultaneously determine the motor blocking minimum local anesthetic concentrations (MMLAC) and the relative potency ratios for racemic bupivacaine, levobupivacaine, and ropivacaine during labor. ⋯ This study confirms a motor blocking hierarchy for the three pipecoloxylidines.
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Reg Anesth Pain Med · Jul 2007
ReviewShould we add clonidine to local anesthetic for peripheral nerve blockade? A qualitative systematic review of the literature.
Although clonidine has been shown to prolong analgesia in central neuraxial blocks, its use in peripheral nerve blocks remains controversial. We performed a systematic review of the current literature to determine the benefit of adding clonidine to peripheral nerve blocks. ⋯ Clonidine improves duration of analgesia and anesthesia when used as an adjunct to intermediate-acting local anesthetics for some peripheral nerve blocks. Side-effects appear to be limited at doses up to 150 mug. Evidence is lacking for the use of clonidine as an adjunct to local anesthetics for continuous catheter techniques. Further research is required to examine the peripheral analgesic mechanism of clonidine.
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Reg Anesth Pain Med · Jul 2007
Hemodynamic effects of thoracic epidural analgesia in ovine hyperdynamic endotoxemia.
Thoracic epidural analgesia (TEA) is increasingly used for perioperative analgesia. If patients with TEA develop sepsis or systemic inflammatory response subsequent to extended surgery the question arises if it would be safe to continue TEA with its beneficial effects of improving gastrointestinal perfusion and augmenting tissue oxygenation. A major concern in this regard is hemodynamic instability that might ensue from TEA-induced vasodilation. The objective of the present study was to assess the effects of TEA on systemic and pulmonary hemodynamics in a sepsis model of hyperdynamic endotoxemia. ⋯ From a hemodynamic point of view, TEA presents as a safe treatment option in sepsis or systemic inflammatory response syndrome.