Regional anesthesia and pain medicine
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Reg Anesth Pain Med · Jan 2012
ED50 of hyperbaric bupivacaine with fentanyl for cesarean delivery under combined spinal epidural in normotensive and preeclamptic patients.
The use of reduced intrathecal doses is advised for spinal anesthesia during cesarean delivery. However, there are inadequate data regarding the minimum effective dose of intrathecal bupivacaine for cesarean delivery. Preeclampsia is caused by an endothelial dysfunction leading to generalized vasoconstriction. Whether this can offset the pregnancy-induced decrease in intrathecal dose requirement caused by epidural venous dilation and consequent thecal compression is not known. There are no data to evaluate the minimum effective dose of intrathecal drug for cesarean delivery in preeclamptic patients. This study aimed to determine the minimum effective dose represented by the ED50 of intrathecal hyperbaric bupivacaine for normotensive and severely preeclamptic patients undergoing elective cesarean delivery. ⋯ When a combined-spinal epidural is planned in normotensive or severely preeclamptic patients for an elective cesarean delivery, the ED50 of intrathecal hyperbaric bupivacaine along with 20 μg of fentanyl is 4.7 mg.
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Reg Anesth Pain Med · Jan 2012
Randomized Controlled Trial Comparative StudyTriple-blind randomized clinical trial of time until sensory change using 1.5% mepivacaine with epinephrine, 0.5% bupivacaine, or an equal mixture of both for infraclavicular block.
Practitioners mix faster-onset, intermediate-duration local anesthetics (LAs) with slower-onset, long-duration LAs to get fast peripheral nerve block (PNB) onset and long duration. We hypothesized that 1.5% mepivacaine (with epinephrine) (mepivacaine) or 1.5% mepivacaine (with epinephrine) mixed with 0.5% bupivacaine (mixed) would reduce PNB sensory onset by 20% or more versus 0.5% bupivacaine alone (bupivacaine). ⋯ Mixing 1.5% mepivacaine (with epinephrine) with 0.5% bupivacaine speeds up PNB sensory (motor) onset compared with 0.5% bupivacaine alone.
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Reg Anesth Pain Med · Jan 2012
Randomized Controlled Trial Comparative StudyUltrasound-guided obturator nerve block: interfascial injection versus a neurostimulation-assisted technique.
Interfascial injection of local anesthetic under ultrasound guidance has been proposed as a new technique for performing an obturator nerve block. We hypothesized that interfascial needle placement could supplant nerve stimulation as the end point for local anesthetic injection during ultrasound-guided obturator nerve block after the division of the obturator nerve. ⋯ In ultrasound-guided obturator nerve block performed after the division of the nerve, injection of local anesthetic between the planes of the adductor muscles is comparable to nerve stimulation.
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Reg Anesth Pain Med · Jan 2012
Three-dimensional/four-dimensional volumetric ultrasound imaging of the sciatic nerve.
Currently, there are limited data on the use of 3-dimensional ultrasound to image peripheral nerves. We undertook this imaging study to determine the feasibility of using 3-dimensional ultrasound imaging to delineate the anatomy of the sciatic nerve. ⋯ We have demonstrated that it is feasible to perform 3-dimensional ultrasound imaging of the sciatic nerve. The anatomic information obtained is more detailed than that with a 2-dimensional scan, which provides better insight into the spatial relationship of the sciatic nerve with its surrounding structures. A distinct "perineural space" was also identified alongside the course of the sciatic nerve, which may play a significant role in sciatic nerve blockade.