Articles: nerve-block.
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Anesthesia and analgesia · Oct 1996
The efficacy of axillary block for surgical procedures about the elbow.
Surgical procedures to the distal humerus, elbow, and proximal ulna and radius are ideally suited to regional techniques. However, axillary block is usually not recommended for surgery about the elbow because blockade at this level may result in inadequate block of the terminal nerves that arise from the medial, posterior, and lateral cords, and provide sensory innervation to the upper arm. This study reports the success rates for interscalene, supraclavicular, and axillary blocks for surgery about the elbow. ⋯ In addition, axillary blocks performed with mepivacaine had a higher success rate (93%) than those performed with bupivacaine (81%) (P < 0.01). There were no patients with perioperative respiratory compromise. These results demonstrate that the axillary approach to the brachial plexus may be successfully used for surgical procedures about the elbow.
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Regional anesthesia · Sep 1996
Case ReportsPeripheral nerve catheterization in the management of terminal cancer pain.
Peripheral nerve catheterization techniques were used in two patients with severe pain associated with the terminal stages of metastatic cancer. The first patient had severe upper limb pain and lymphedema secondary to breast carcinoma, and the second patient had an acutely ischemic leg secondary to pelvic obstruction from an ovarian tumor. The goal of treatment was to relieve the pain, which was resistant to opioid drugs, and to optimize the quality of life that remained, estimated to be only a few weeks. ⋯ Peripheral nerve catheterization proved beneficial in two patients who presented with difficult pain management problems and should be more widely considered for the relief of severe cancer-related pain in both the upper and lower limbs.
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The enantiomerically pure (S-enantiomer) amide local anaesthetic drug ropivacaine blocked nerve fibres responsible for transmission of pain (Aδ and fibres) more completely than those that control motor function (Aβ fibres) in in vitro studies. The drug shares the biphasic vascular effects common to the amide local anaesthetic drug class. In vitro studies indicate that ropivacaine is less cardiotoxic than equimolar concentrations of bupivacaine. Apart from one trial in women undergoing hysterectomy, clinical studies that compared the efficacy of different doses of epidurally administered ropivacaine in patients undergoing various surgical procedures did not reveal any consistent dose-related differences with respect to sensory blockade. However, motor blockade did become more intense as the dose of ropivacaine increased. Overall, direct comparisons show that epidural ropivacaine is less potent than epidural bupivacaine when the 2 drugs are administered at the same concentration. However, this difference is less marked in terms of sensory blockade than motor blockade. The greater degree of separation between motor and sensory blockade seen with ropivacaine relative to bupivacaine is more apparent at the lower end of the dosage scale. Nevertheless, higher doses of ropivacaine than bupivacaine are generally required to elicit equivalent anaesthetic effects. Ropivacaine has been shown to induce successful brachial plexus anaesthesia when given at a concentration of 5 mg/ml, but not 2.5 mg/ml, and was as effective as bupivacaine in comparative studies in this indication. Limited data indicate that continuous epidural infusion of ropivacaine post-operatively reduces postsurgical pain in a dose-related manner. Morphine consumption was also reduced. Higher doses of ropivacaine were significantly more effective than placebo. Similarly, ropivacaine controlled postsurgical pain when infiltrated directly into surgical wound sites (i.e. wound infiltration) and was as effective as bupivacaine, and more effective than placebo, in this regard. Adverse events associated with epidurally administered ropivacaine include hypotension, nausea, bradycardia, transient paraesthesia, back pain, urinary retention and fever. The drug appears to have an adverse event profile similar to that of bupivacaine. In animal studies, overdoses of ropivacaine were better tolerated than overdoses of bupivacaine but not lidocaine (lignocaine). Human volunteers tolerated a higher intravenous dosage of ropivacaine than bupivacaine before developing initial signs of toxicity. Thus, ropivacaine, according to animal data, is less cardiotoxic than bupivacaine. Based on available clinical data, ropivacaine appears to be as effective and well tolerated as bupivacaine when equianalgesic doses are compared. The greater degree of separation between motor and sensory blockade seen with ropivacaine relative to bupivacaine at lower concentrations (≈5 mg/ml) will be advantageous in certain applications. ⋯ Recommended epidural doses of ropivacaine for surgical anaesthesia range between 113 and 200mg. Different doses can be achieved by varying either the concentration or volume of solution injected. Epidural ropivacaine administered to control postsurgical pain can be given as a 20 to 40mg bolus with 20 to 30mg top-up doses at ≥30-minute intervals or as a 2 mg/ml continuous epidural infusion at a rate of 6 to 14 ml/h (lumbar) or 4 to 8 ml/h (thoracic).