Regional anesthesia and pain medicine
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Dose-finding studies enable the successful conduct of peripheral nerve blocks by ensuring the administration of appropriate doses of local anesthetic. However, the optimal dose-finding methodology remains ambiguous. In this research methodology article, we set out to review the basic aspects pertaining to dose-response curves (graded vs quantal), the pharmacodynamic indices required by dose-finding studies, the properties of different dose-finding methods (sigmoidal dose-response curve analysis, Dixon-Mood method, Biased Coin Design, and Bayesian analysis), as well as strategies and recommendations for future research.
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Reg Anesth Pain Med · Nov 2014
Cervical Transforaminal Epidural Steroid Injections: A Proposal for Optimizing the Preprocedural Evaluation With Available Imaging.
Cervical transforaminal epidural steroid injection (CTFESI) has been used to treat cervical radicular pain; however, rare but serious complications such as cerebellar or spinal cord infarction have been reported. The most probable causes of the serious complications include vertebral artery trauma, spasm, or accidental arterial injection of particulate steroid. Several recommendations have been made to improve the safety of CTFESI; however, evaluation and risk assessment of the patient's anatomy by the interventionist have not been sufficiently emphasized. ⋯ Special attention should be paid to the vital structures such as the vertebral artery, neural foramen, and carotid artery. A preprocedural roadmap for the safest predicted needle trajectory can be created by simulation using the patient's available magnetic resonance imaging scans. These considerations may guide and help the interventionist to minimize the risk of inadvertent needle placement involving vital structures such as the vertebral artery or carotid artery.
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Reg Anesth Pain Med · Nov 2014
Evaluation of Epidural and Peripheral Nerve Catheter Heating During Magnetic Resonance Imaging.
Many epidural and peripheral nerve catheters contain conducting wire that could heat during magnetic resonance imaging (MRI), requiring removal for scanning. ⋯ Most but not all catheters can be left in place during 1.5-T MRI scans. Heating of less than 3°C during MRI for most catheters is not expected to be injurious. While heating was lower at 1.5 T versus 3 T, performance differences between products underscore the need for safety testing before performing MRI.
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Reg Anesth Pain Med · Nov 2014
Mechanisms Underlying Midazolam-Induced Peripheral Nerve Block and Neurotoxicity.
The benzodiazepine midazolam has been reported to facilitate the actions of spinally administrated local anesthetics. Interestingly, despite the lack of convincing evidence for the presence of γ-aminobutyric acid type A (GABAA) receptors along peripheral nerve axons, midazolam also has been shown to have analgesic efficacy when applied alone to peripheral nerves.These observations suggest midazolam-induced nerve block is due to another site of action. Furthermore, because of evidence indicating that midazolam has equal potency at the benzodiazepine site on the GABAA receptor and the 18-kd translocator protein (TSPO), it is possible that at least the nerve-blocking actions of midazolam are mediated by this alternative site of action. ⋯ Our results indicate that processes underlying midazolam-induced nerve block and neurotoxicity are separable, and suggest that selective activation of TSPO may facilitate modality-selective nerve block while minimizing the potential for neurotoxicity.