Articles: nerve-block.
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In this review, emphasis is placed on adjuvant drugs that are already in clinical use. The list of adjuvants studied during the review period includes adrenaline, clonidine, ketamine, neostigmine, nondepolarizing muscle relaxants, and nonsteroidal antiinflammatory drugs. Some future aspects are considered in a couple of experimental studies on slow-release local anaesthetic formulations. ⋯ Adrenaline and opioids may be regarded as the best investigated and most important adjuvants in regional anaesthesia. Other drugs, such as clonidine and neostigmine, may prolong analgesia in various regional anaesthetic techniques, but possible side effects may limit their clinical application. Further development is needed concerning extra-long acting analgesic formulations.
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Spinal and peridural anaesthesia has several advantages over general anaesthesia due to their low influence to endocrine and metabolic activity and their capacity to reduce postoperative surgical complications, intraoperative bleeding and deep venous thromboembolism incidence. Nevertheless, these anaesthesiologic techniques have a high risk of severe neurological events in patients treated with anticoagulant therapies and prophylaxis. However, this complication is rarely found in literature. ⋯ Anaesthetists must know the use and pharmacological properties of anticoagulant drugs in order to be able of giving up or modifying them during perioperative time, evaluating the risk of bleeding episodes and thrombotic events. An analysis of the literature has been made in order to establish favourable conditions, risk factors, international guide-lines and the real incidence of haemorrhagic complications associated to central blocks in patients being treated with drugs that modify their coagulative status. The survey of the literature and the international guide-lines shows that neuraxial anaesthesia should be performed in selected patients, respecting the free intervals of anticoagulant drugs, carrying out a correct postoperative neurological monitoring and evaluating, case by case, the risks and benefits of the procedure.
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Anesthesia and analgesia · Oct 2003
The acute myotoxic effects of bupivacaine and ropivacaine after continuous peripheral nerve blockades.
Bupivacaine causes muscle damage. However, the myotoxic potency of ropivacaine is still unexplored. Therefore, we performed this study to compare the effects of bupivacaine and ropivacaine on skeletal muscle tissue in equipotent concentrations. Femoral nerve catheters were inserted into anesthetized minipigs, and 20 mL of either bupivacaine (5 mg/mL) or ropivacaine (7.5 mg/mL) was injected. Subsequently, bupivacaine (2.5 mg/mL) and ropivacaine (3.75 mg/mL) were continuously infused over 6 h. Control animals were treated with corresponding volumes of normal saline. Finally, muscle samples were dissected at injection sites. After processing and staining, histological patterns of muscle damage were blindly examined, scored (0 = no damage to 3 = myonecrosis), and statistically analyzed. After normal saline, only interstitial edema was found. Bupivacaine treatment caused severe tissue damage (score, 2.3 +/- 0.7), whereas ropivacaine induced fiber injury of a significantly smaller extent (score, 1.3 +/- 0.8). Furthermore, bupivacaine, but not ropivacaine, induced apoptosis in muscle fibers. In summary, both drugs induce muscle damage with similar histological patterns. Compared with bupivacaine, which induces both necrosis and apoptosis, the tissue damage caused by ropivacaine is significantly less severe. We conclude that ropivacaine's myotoxic potential is more moderate in comparison with that of bupivacaine. ⋯ After continuous peripheral nerve blockades, the long-acting local anesthetics bupivacaine and ropivacaine both induce fiber necrosis in porcine skeletal muscle tissue. In comparison with ropivacaine, bupivacaine causes tissue damage of a significantly larger extent and additionally induces apoptosis in skeletal muscle cells.
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Facet or zygapophysial joint blocks are used extensively in the evaluation of chronic spinal pain. However, there is a continuing debate about the value and validity of facet joint blocks in the diagnosis of chronic spinal pain. The value of diagnostic facet joint injections may have been overlooked in the medical literature. ⋯ The diagnostic accuracy of controlled local anesthetic facet joint blocks is high in the diagnosis of chronic spinal pain.