Articles: nerve-block.
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Anesthesia and analgesia · Aug 2001
The pharmacokinetics and pharmacodynamics of bupivacaine-loaded microspheres on a brachial plexus block model in sheep.
We evaluated bupivacaine-loaded microspheres (B-Ms) using a brachial plexus block model in sheep. In the first step, pharmacokinetic characterization of 75 mg bupivacaine hydrochloride (B-HCl) (IV infusion and brachial plexus block) was performed (n = 12). In the second step, a brachial plexus block dose response study of B-HCl was performed with 37.5 mg, 75 mg, 150 mg, 300 mg, and 750 mg. As a comparison, evaluations were performed using a 750-mg bupivacaine base (B). In the third step, evaluations of brachial plexus block were performed with B-Ms (750 mg of B as B-Ms) using two formulations, 60/40 and 50/50 (w/w %); drug-free microspheres were also evaluated. Toxicity evaluations were also performed after IV administration of B-HCl (750 mg and 300 mg), B-Ms (750 mg), and drug-free microspheres (30 mL over 1 min). As the B-HCl dose increased, the time of onset of block decreased and the duration of complete motor blockade increased at the expense of an increase in bupivacaine plasma concentrations. The time of maximum concentration appeared to be independent of the B-HCl dose. In brachial plexus block, a 37.5-mg dose of B-HCl did not induce motor blockade whereas a dose of 750 mg of B-HCl was clinically toxic. In the case of IV administration, doses of 300 mg of B-HCl were as toxic as 750 mg of B-HCl. Compared with the 75 mg of B-HCl administration for brachial plexus block, administration of 750 mg of B as B-Ms increased the duration of complete motor blockade without significant difference in maximum concentration. No significant clinical difference between the two formulations of B-Ms was demonstrated. The IV administration of B-Ms was safe. We conclude that the controlled release of bupivacaine from microspheres prolonged the brachial plexus block without obvious toxicity. ⋯ Administration of 750 mg of bupivacaine as loaded-microspheres resulted in prolongation of brachial plexus block in sheep. The peak plasma concentration was not significantly larger than that obtained with 75 mg of plain bupivacaine. The motor blockade was increased more than six times compared with 75 mg plain bupivacaine.
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Anesthesia and analgesia · Aug 2001
An evaluation of the infraclavicular block via a modified approach of the Raj technique.
Infraclavicular plexus block has recently become a technique of increasing interest. However, no approach has provided easily identifiable landmarks, good conditions for catheter placement, and lack of complications (mainly pneumothorax). We describe a modified approach of the Raj technique based on the identification of the anterior acromial process, jugular notch, and emergence of the axillary artery within the axillary fossa, with the arm abducted to 90 degrees and elevated by approximately 30 degrees. We evaluated the clinical characteristics of this approach by injecting 40 to 50 mL of ropivacaine 0.6% in 150 patients scheduled for elective surgery of the forearm, wrist, or hand. Success was defined as a sensory block of the 5 nerves with territories distal to the elbow within 30 min after performing the block. The success rate was 97% when a distal response (flexion or extension of the wrist or fingers) was elicited and 44% when a proximal (contraction of the triceps, biceps) was obtained using a nerve stimulator. Complications were rare: aspiration of blood was seen in 2% of patients and hematoma was seen at the puncture site in 0.6%; no pneumothorax occurred. Eleven patients (7%) complained of some pain during the procedure. We conclude that the modified approach of the Raj technique for infraclavicular block is very effective when a distal nerve stimulator response is obtained with a small complication rate and a high degree of patient satisfaction. ⋯ We describe a modified approach of the Raj technique for the infraclavicular brachial plexus. The elicitation of a distal nerve stimulator response is associated with a high success rate, a low incidence of complications and a high degree of patient satisfaction.
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Anasthesiol Intensivmed Notfallmed Schmerzther · Aug 2001
Case Reports[Frozen shoulder--MRI-verified continuous block of suprascapular nerve].
Suprascapular nerve block may provide sufficient analgesia in painful immobilisation of the shoulder joint. In the following case report a 41 year old male presenting with adhesive capsulitis (frozen shoulder) has been treated successfully by performing continuous delivery of local anesthetics to the suprascapular nerve via catheter. The location of the catheter has been verified using MRI examination. ⋯ The technique of catheterization using a nerve stimulator and alternative peripheral nerve blocks are discussed. In summary, continuous suprascapular nerve block offers an advantageous alternative for pain relief in patients with frozen shoulder. It may provide better pain control and earlier discharge in the ambulatory setting than repetetive single dose blocks.
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Ann Fr Anesth Reanim · Aug 2001
Case Reports[Ilio-inguinal Ilio-hypogastic nerve block with a single puncture: an alterantive for anesthesia in emergency inguinal surgery].
The authors describe the anaesthetic procedure for a strangulated hernia repair needing resection and anastomosis of the small bowel in an adult patient. This procedure was performed with an ilio-inguinal/ilio-hypogastric nerve block according to a paediatrical simplified technique with a single puncture. ⋯ This block associated with a very light sedation was sufficient for all the surgical procedure, and postoperative analgesia was efficient over 3 hours. This simplified nerve block, better than the conventional approach for the clinical practice, represents a recommended alternative for hernia repair in emergency for high risk patients who could have a general anaesthesia or a central block.
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The research on conductive analgesia induced by perineural opioids generated a large body of conflicting data. In this study we reassessed the antinociceptive response to perineural administration of morphine, fentanyl or meperidine in a rat model. ⋯ The results indicate that perineural fentanyl or morphine do not produce analgesia. Perineural block produced by meperidine was attributed to local anesthetic-like effect, rather than to drug interaction with opioid receptor.