Regional anesthesia and pain medicine
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Reg Anesth Pain Med · Sep 2011
Comparative StudyLocal anesthetic Schwann cell toxicity is time and concentration dependent.
Peripheral nerve blocks with local anesthetics (LAs) are commonly performed to provide surgical anesthesia or postoperative analgesia. Nerve injury resulting in persistent numbness or weakness is a potentially serious complication. Local anesthetics have previously been shown to damage neuronal and Schwann cells via several mechanisms. We sought to test the hypothesis that LAs are toxic to Schwann cells and that the degree of toxicity is directly related to the concentration of LA and duration of exposure. Intraneural injection of LAs has been shown to produce nerve injury. We sought to test the hypothesis that a prolonged extraneural infusion of LA can also produce injury. ⋯ Local anesthetics induce Schwann cell death in a time- and concentration-dependent manner. Bupivacaine and ropivacaine have greater toxicity at intermediate concentrations, and prolonged exposure to bupivacaine produces significant toxicity even at low concentrations. Brief exposure to high concentrations of bupivacaine damages Schwann cells. Prolonged extraneural infusion of bupivacaine results in nerve injury.
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Reg Anesth Pain Med · Sep 2011
Comparative StudyGlutamate release and neurologic impairment after intrathecal administration of lidocaine and bupivacaine in the rat.
Local anesthetic-induced neurotoxicity is one of the potential causes of postspinal anesthesia neurologic injury. Many experimental and clinical studies have demonstrated that lidocaine is more neurotoxic than bupivacaine. The mechanisms of local anesthetic-induced neurotoxicity remain unclear. Glutamate is an excitatory amino acid and widely exists in the central nervous system. Overstimulation of the glutamate receptors may produce neuronal toxic effect. In this study, we used in vivo microdialysis to examine the glutamate release in cerebrospinal fluid (CSF) after intrathecal lidocaine and bupivacaine injection. ⋯ Intrathecal lidocaine caused a concentration-dependent increase of the CSF glutamate release and postinjection neurologic impairment; these effects can be reversed by MK-801. However, intrathecal bupivacaine shows no influence. We suggest that glutamate may be involved in the pathogenesis of lidocaine-induced spinal neurotoxicity.
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Reg Anesth Pain Med · Sep 2011
Patient experiences as knowledge for the evidence base: a qualitative approach to understanding patient experiences regarding the use of regional anesthesia for hip and knee arthroplasty.
It is reported that patients continue to have misgivings about regional anesthesia (RA) despite strong evidence to support its use for hip and knee replacement surgery. To date, no one has had an opportunity to study the experiences of patients who have undergone both types of anesthesia for these procedures. ⋯ These findings have important implications. First, many patients were surprisingly neutral about the procedure and seemed more fearful of anesthesia in general rather than of either technique specifically. This finding, combined with patient's influence by clinician preference, underscores the importance of physician support for RA. Some participants identified one of their misgivings about RA as being fear of being awake, which is consistent with the medical literature. Our findings also support the idea that from a patient's perspective, appropriate sedation while undergoing RA may be important.
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Reg Anesth Pain Med · Sep 2011
Proactive error analysis of ultrasound-guided axillary brachial plexus block performance.
Detailed description of the tasks anesthetists undertake during the performance of a complex procedure, such as ultrasound-guided peripheral nerve blockade, allows elements that are vulnerable to human error to be identified. We have applied 3 task analysis tools to one such procedure, namely, ultrasound-guided axillary brachial plexus blockade, with the intention that the results may form a basis to enhance training and performance of the procedure. ⋯ This study presents a formal analysis of (i) the specific tasks that might be associated with the safe and effective performance of the procedure and (ii) the most critical errors likely to occur as trainees learn to perform the procedure. Potential applications of these data include curricular development and the design of tools to teach and assess block performance.