Regional anesthesia and pain medicine
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Interscalene brachial plexus block is often used for surgeries involving the shoulder and upper arm. Known complications include phrenic nerve paralysis, intravascular injection, and cervical epidural block. We report a patient who developed acute hypoxia immediately following this block, presumably secondary to an acute pulmonary thromboembolus (PTE) coupled with phrenic nerve paralysis. ⋯ This case report suggests that manipulations and vasodilation related to an interscalene block may have facilitated the dislodgement of a pre-existing upper extremity thrombus.
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Reg Anesth Pain Med · Jan 2002
Intrathecal lidocaine causes posterior root axonal degeneration near entry into the spinal cord in rats.
The neurotoxicity of lidocaine is not fully understood, and the primary lesion of lidocaine-induced spinal neurotoxicity has not been defined. Here we examine the effects of various concentrations of intrathecally administered lidocaine. ⋯ Our results suggest that spinal lidocaine neurotoxicity after supra-clinical concentrations of lidocaine is limited initially to the posterior roots at their entry to the spinal cord, and the extent and severity of the lesions are closely associated with lidocaine concentration. Unlike severe lesions in rats injected with 20% lidocaine, mild lesions caused by lower concentrations may not manifest neurofunctional deficits.
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Reg Anesth Pain Med · Jan 2002
Gabapentin decreases membrane calcium currents in injured as well as in control mammalian primary afferent neurons.
Neuropathic pain following injury to peripheral sensory neurons is a common clinical problem and frequently difficult to treat. Gabapentin (GBP), a novel anticonvulsant, has significant analgesic effects in clinical neuropathic states and in relevant preclinical models, but its mechanism of action remains unclear. Because calcium currents play a significant role in neuronal function, this study was designed to assess the effect of GBP on the membrane voltage-activated inward calcium currents (I(Ca)) in dorsal root ganglia (DRG) primary afferent neurons of neuropathic versus control rats. ⋯ GBP, at clinically relevant concentrations, results in significant reduction of I(Ca) in both sham and neuropathic neurons, while in nonoperated rats reduced I(Ca) to a smaller degree. Sensitivity to drug was not affected by neuropathy. This current inhibition is partly voltage dependent. Depression of I(Ca) may be partly related to the binding of the drug to the alpha(2)delta modulatory subunit of the voltage activated calcium channels (VACC). Analgesia may be due to diminished release of neurotransmitter by sensory neurons, a Ca(2+)-dependent process.
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Reg Anesth Pain Med · Jan 2002
Randomized Controlled Trial Comparative Study Clinical TrialEpidural infusions for labor analgesia: a comparison of 0.2% ropivacaine, 0.1% ropivacaine, and 0.1% ropivacaine with fentanyl.
Epidural infusion of 0.2% ropivacaine is recommended by the manufacturer for labor analgesia, but lower concentrations may be effective. The objective of this study was to compare 0.1% ropivacaine with 0.2% ropivacaine and to examine the effect of addition of fentanyl. ⋯ We conclude that epidural infusion of 0.1% ropivacaine alone at 10 mL/h provided adequate analgesia in the first stage of labor, and that the addition of 2 microg/mL fentanyl to that concentration improved analgesia to a quality similar to 0.2% ropivacaine alone.