Regional anesthesia and pain medicine
-
Reg Anesth Pain Med · Sep 2012
Randomized Controlled TrialRandomized study of the effect of local anesthetic volume and concentration on the duration of peripheral nerve blockade.
Ultrasound guidance reduces the required local anesthetic volume for successful peripheral nerve block, but it is unclear whether this influences block duration. We investigated the ropivacaine volume and concentration effect on interscalene block duration. ⋯ Block duration is influenced by both local anesthetic volume and concentration, a finding of increasing relevance with the current trend to lower volumes for ultrasound-guided regional anesthesia.
-
Reg Anesth Pain Med · Sep 2012
Brachial plexus root injection in a human cadaver model: injectate distribution and effects on the neuraxis.
The potential for injection into the brachial plexus root at cervical levels must be considered during interscalene block or chronic pain interventions in the neck, but this phenomenon has not been well studied. In this investigation, we performed injections into the brachial plexus roots of unembalmed cadavers, with real-time ultrasound guidance, to evaluate the proximal and distal spread of the injected fluids, the potential of the injectate to reach the neuraxis, and whether the injectate could migrate into the actual substance of the spinal cord itself. ⋯ Injection directly into the neural tissue of a brachial plexus root in a cadaver model produced high pressures suggestive of intrafascicular injection and widespread flow of the injectate through the distal brachial plexus. However, proximal movement of the dye-containing injectate was more restricted, with only 1 of the injections leading to epidural spread and no apparent effects on the spinal cord.
-
Reg Anesth Pain Med · Sep 2012
The sensory territory of the lateral cutaneous nerve of the thigh as determined by anatomic dissections and ultrasound-guided blocks.
A femoral block sometimes fails to provide complete sensory anesthesia of the anterior aspect of middle and distal thigh, and a block of the lateral cutaneous nerve of the thigh (LCN) is often necessary to supplement it. The goal of this study was to demonstrate, both in the anatomy laboratory and in the clinical setting, a possible contribution of the LCN to the innervation of the anterior thigh. ⋯ Our results, coming from a small sample, seem to indicate that the LCN may contribute to the innervation of the anterior thigh in some cases. A block of the LCN could be considered when a femoral block has failed to produce the expected area of anesthesia.
-
Reg Anesth Pain Med · Sep 2012
Duration and local toxicity of sciatic nerve blockade with coinjected site 1 sodium-channel blockers and quaternary lidocaine derivatives.
Quaternary lidocaine derivatives (QLDs) have recently received much attention because of their potential application in prolonged or sensory-selective local anesthesia. However, associated tissue toxicity is an impeding factor that makes QLDs unfavorable for clinical use. Based on the proposed intracellular site of action, we hypothesized that nerve blocks obtained from lower concentrations of QLDs would be enhanced by the coapplication of extracellularly acting site 1 sodium-channel blocker, resulting in prolonged block duration but with minimal tissue toxicity. ⋯ Coadministration of site 1 sodium-channel blockers and QLDs greatly prolongs the duration of peripheral nerve block without enhancing local tissue injury, but minimal myotoxicity still persists. It is not clear that the risks of QLDs are outweighed by the benefits in providing prolonged nerve blockade.