British journal of anaesthesia
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Failed epidural anaesthesia or analgesia is more frequent than generally recognized. We review the factors known to influence the success rate of epidural anaesthesia. Reasons for an inadequate epidural block include incorrect primary placement, secondary migration of a catheter after correct placement, and suboptimal dosing of local anaesthetic drugs. ⋯ Addition of adjuvants, especially opioids and epinephrine, may substantially increase the success rate of epidural analgesia. Adjuvant opioids may have a spinal or supraspinal action. The use of patient-controlled epidural analgesia with background infusion appears to be the best method for postoperative analgesia.
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Cerebral microdialysis (MD) has proven to be a valuable clinical and research tool in neuroscience. It allows sampling of endogenous and exogenous molecules of interest from the extracellular fluid (ECF) of the brain. MD has also been successfully used to assess drug delivery to the target tissues in pharmacokinetic (PK) studies. ⋯ Some studies suggest that commonly used antibiotics do not reach a therapeutic concentration range in brain ECF. Studies reviewed in this article are small and performed in different patient populations (brain tumour, head injury, epilepsy) using different methodological approaches to the drug recovery estimation. Nevertheless, they provide interesting and important data on the variability of antibiotic penetration that could be utilized for PK/PD studies and which may have clinical relevance.