Regional anesthesia and pain medicine
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Reg Anesth Pain Med · Sep 2004
Comparative StudyThe use of magnetic resonance imaging to evaluate the accuracy of a handheld ultrasound machine in localizing the sciatic nerve in the popliteal fossa.
Ultrasound has become an increasingly popular modality in facilitating the performance of peripheral nerve blocks. There is a paucity of data describing techniques of ultrasound-guided sciatic nerve blocks. By using magnetic resonance imaging (MRI) as a gold standard, the objective of this study was to describe the ability of a handheld ultrasound machine to accurately locate the sciatic nerve. ⋯ The data presented here suggest that the specific ultrasound machine evaluated in this study can accurately localize the sciatic nerve in the popliteal fossa.
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Reg Anesth Pain Med · Sep 2004
Randomized Controlled Trial Clinical TrialHearing loss does not occur in young patients undergoing spinal anesthesia.
Although uncommon, hearing loss after spinal anesthesia has been described. Vestibulocochlear dysfunction after spinal anesthesia in which 22-gauge and 25-gauge Quincke needles were used was investigated to determine if needle size affected hearing. ⋯ We were unable to induce hearing loss in young patients undergoing spinal anesthesia by injecting the anesthetic with a 22-gauge or a 25-gauge Quincke needle.
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Reg Anesth Pain Med · Sep 2004
Ultrasound visibility of needles used for regional nerve block: an in vitro study.
Ultrasound visibility of regional block needles is a critical component for safety and success of regional anesthetic procedures. The aim of the study was to formally assess factors that influence ultrasound visibility of needles used in regional anesthesia. ⋯ The results of our in-vitro study suggest a number of factors enhancing ultrasound visibility of regional block needles. The use of needles in the largest possible size inserted with a medium-size guide wire provides the best ultrasound visibility. Analysis of the approach angle favors needle insertion parallel to the transducer. The consideration of these factors may improve safety and success of ultrasound-guided regional blocks.
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Reg Anesth Pain Med · Sep 2004
Neurologic and histopathologic evaluation after high-volume intrathecal amitriptyline.
Accumulating evidence indicates that amitriptyline decreases pain sensation when administered orally, intraperitoneally, or for sciatic nerve block. Previous reports of intrathecal administration of amitriptyline have yielded inconsistent results. The failure of amitriptyline to provide antinociception may partly be related to its high logP (octanol-water partition coefficient) and consequent poor spread within the cerebrospinal fluid. We evaluated spinal block after various concentrations of amitriptyline administered intrathecally in a fixed high volume. ⋯ At lower doses, intrathecal injection of high volumes of amitriptyline results in long-acting spinal block. At higher doses, intrathecal amitriptyline results in irreversible neurologic deficit. Therefore, we do not recommend the use of intrathecal amitriptyline because of a very low therapeutic index.
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Reg Anesth Pain Med · Sep 2004
Combination of intraneural injection and high injection pressure leads to fascicular injury and neurologic deficits in dogs.
Unintentional intraneural injection of local anesthetics may cause mechanical injury and pressure ischemia of the nerve fascicles. One study in small animals showed that intraneural injection may be associated with higher injection pressures. However, the pressure heralding an intraneural injection and the clinical consequences of such injections remain controversial. Our hypothesis is that an intraneural injection is associated with higher pressures and an increase in the risk of neurologic injury as compared with perineural injection. ⋯ High injection pressures at the onset of injection may indicate an intraneural needle placement and lead to severe fascicular injury and persistent neurologic deficits. If these results are applicable to clinical practice, avoiding excessive injection pressure during nerve block administration may help to reduce the risk of neurologic injury.