Local and regional anesthesia
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Fracture of femur is a painful bone injury, worsened by any movement. This prospective study was performed to compare the analgesic effects of femoral nerve block (FNB) with intravenous (IV) fentanyl prior to positioning patients with fractured femur for spinal block. ⋯ We were unable to demonstrate a benefit of FNB over IV fentanyl for patient positioning before spinal block. However, FNB can provide postoperative pain relief, whereas side effects of fentanyl must be considered, and analgesic dosing should be titrated based on pain scores. A multimodal approach (FNB + IV fentanyl) may be a possible option.
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Continuous femoral nerve blocks are a part of the multimodal perioperative anesthetic regimen following total knee replacement. Elicitation of a quadriceps muscle contraction (QC) at placement is desirable. We prospectively evaluated the relationship between elicited motor response and threshold current with block success in situ femoral nerve catheters after total knee replacement. ⋯ The elicited motor response and current threshold from a stimulating femoral catheter measured prior to local anesthetic injection is an important determinant of the success of femoral nerve block following bolus administration.
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Regional anesthesia and analgesia have been associated with improved analgesia, decreased postoperative nausea and vomiting, and increased patient satisfaction for many types of surgical procedures. In obstetric anesthesia care, it has also been associated with improved maternal mortality and major morbidity. ⋯ Infection and hemorrhagic complications, particularly with neuraxial blocks, can cause neurological adverse events. More commonly, however, there are no associated secondary factors and some combination of needle trauma, intraneural injection, and/or local anesthetic toxicity may be associated, but their individual contributions to any event are difficult to define.
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We measured dynamic biomechanics of loss-of-resistance (LOR) epidural placement in prone cadavers, focussing on the period immediately following LOR, to estimate forces acting on the tissue of the epidural space. ⋯ Formalin-preserved cadavers are too stiff to make them an experimental model from which we can generalize to live humans, although we were successful in entering the epidural space and testing the instrumentation for further studies on live animals or humans. Continuous pressure on the plunger while advancing the epidural needle may "blow" the dura away from the needle tip and help prevent dural puncture. Better results are seen with saline rather than air.
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Cardiovascular collapse from accidental local anesthetic toxicity is a rare but catastrophic complication of regional anesthesia. The long-acting amide local anesthetics bupivacaine, levobupivacaine and ropivacaine have differential cardiac toxicity, but all are capable of causing death with accidental overdose. In recent times, the chance discovery that lipid emulsion may improve the chance of successful resuscitation has lead to recommendations that it should be available in every location where regional anesthesia is performed. This review will outline the mechanisms of local anesthetic toxicity and the rationale for lipid emulsion therapy.