Articles: nerve-block.
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Anesthesia and analgesia · May 2002
The effects of age on neural blockade and hemodynamic changes after epidural anesthesia with ropivacaine.
We studied the influence of age on the neural blockade and hemodynamic changes after the epidural administration of ropivacaine 1.0% in patients undergoing orthopedic, urological, gynecological, or lower abdominal surgery. Fifty-four patients were enrolled in one of three age groups (Group 1: 18-40 yr; Group 2: 41-60 yr; Group 3: > or=61 yr). After a test dose of 3 mL of prilocaine 1.0% with epinephrine 5 microg/mL, 15 mL of ropivacaine 1.0% was administered epidurally. The level of analgesia and degree of motor blockade were assessed, and hemodynamic variables were recorded at standardized intervals. The upper level of analgesia differed among all groups (medians: Group 1: T8; Group 2: T6; Group 3: T4). Motor blockade was more intense in the oldest compared with the youngest age group. The incidence of bradycardia and hypotension and the maximal decrease in mean arterial blood pressure during the first hour after the epidural injection (median of Group 1: 11 mm Hg; Group 2: 16 mm Hg; Group 3: 29 mm Hg) were more frequent in the oldest age group. We conclude that age influences the clinical profile of ropivacaine 1.0%. The hemodynamic effects in older patients may be caused by the high thoracic spread of analgesia, although a diminished hemodynamic homeostasis may contribute. ⋯ Analgesia levels after the epidural administration of 15 mL of ropivacaine 1.0% increase with increasing age. This is associated with an increased incidence of hypotension in the elderly, although an effect of age on the hemodynamic homeostasis may have contributed. It appears that epidural doses should be adjusted for elderly patients.
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Anesthesia and analgesia · May 2002
Selective and long-lasting neural blockade with resiniferatoxin prevents inflammatory pain hypersensitivity.
Capsaicin can produce a selective and long-lasting neural blockade. Resiniferatoxin (RTX) is an ultrapotent vanilloid agonist with a unique spectrum of activities different from that of capsaicin. We sought to determine whether a single application of RTX to a peripheral nerve could completely prevent the long-lasting mechanical hyperalgesia caused by carrageenan injection. In rat experiments, RTX (0.001%) was administered percutaneously to the sciatic and saphenous nerves before the intraplantar injection of carrageenan. Responses to noxious mechanical (pressure on the paw) and thermal (hot plate) stimulations and changes in paw circumference were measured at various time intervals for 8 days after treatment. The administration of RTX resulted in mechanical and thermal hypoalgesia (for 2 and 8 days, respectively). Inflammatory hyperalgesia was completely prevented by the precarrageenan injection of RTX. Inflammatory enhancement of paw circumference was reduced by RTX (12.0 +/- 2.4 mm versus 6.9 +/- 3.4 mm, P < 0.005). We suggest that the selective nature of the effect of vanilloid agonists on nociception could provide an opportunity for prolonged neural blockade when early mobilization and/or preservation of protective sensation are required. ⋯ We report that an ultrapotent vanilloid agonist resiniferatoxin can provide a selective and long-lasting neural blockade. Applied to the sciatic and saphenous nerves, it completely prevented pain hypersensitivity caused by prolonged inflammatory process (injection of carrageenan into the paw).
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Anesthesia and analgesia · Apr 2002
Continuous three-in-one block for postoperative pain after lower limb orthopedic surgery: where do the catheters go?
Continuous three-in-one block is widely used for postoperative analgesia after proximal lower limb surgery, but location of the catheter has not been well addressed in the literature. We prospectively studied, in 100 patients, the characteristics of catheter threading under the iliac fascia and the correlations between catheter tip location and effective sensory and motor blockade of the three principal nerves of the lumbar plexus. Postoperatively, in conscious patients, 16 to 20 cm of a catheter was placed in the fascial sheath after femoral nerve location with a nerve stimulator. Contrast media (3 mL Iopamidol 390) was injected, and the catheter tip was located by means of an anteroposterior pelvic radiograph. An equal-volume mixture of 0.5% bupivacaine/2% lidocaine with epinephrine (30 mL) was injected through the catheter. Patient and catheter-insertion characteristics were noted. Thirty minutes after injection, sensory blockade was evaluated in the cutaneous territories of the lateral femoral cutaneous, femoral, and obturator nerves, along with motor blockade of the last two nerves. Pain scores at 30 min were also recorded. Seven block failures were noted. The tip of the catheter reached the lumbar plexus (Group 1) in 23% of the patients and lay deep to the medial (Group 2) or lateral (Group 3) part of the fascia iliaca in 33% and 37% of the patients, respectively. Demographic data and catheter threading characteristics were comparable among the groups. A three-in-one block was noted in 91% of Group 1 patients, but in only 52% and 27% of Group 2 and 3 patients, respectively (P < 0.05). Comparing Group 2 and 3 patients, sensory block was achieved in respectively 100% and 94% for the femoral nerve, 52% and 94% for the lateral femoral cutaneous nerve (P < 0.05), and 82% and 27% for the obturator nerve (P < 0.05). Visual analog scale pain scores on movement were significantly lower in Group 1 patients (P < 0.05). We conclude that during a continuous three-in-one block, the threaded catheter rarely reached the lumbar plexus. The quality of sensory and motor blockade and initial pain relief depend on the location of the catheter tip under the fascia iliaca. ⋯ The course of a continuous three-in-one block catheter is unpredictable. Only 23% of the catheters lie near the lumbar plexus. The success of sensory and motor blocks, as well as postoperative analgesia, depend on the position of the catheter under the fascia iliaca.
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Anesthesia and analgesia · Apr 2002
Randomized Controlled Trial Comparative Study Clinical TrialA double-blinded, randomized comparison of either 0.5% levobupivacaine or 0.5% ropivacaine for sciatic nerve block.
To compare intraoperative and postoperative clinical properties of levobupivacaine and ropivacaine for sciatic nerve block, 50 ASA physical status I and II patients undergoing hallux valgus repair received a femoral nerve block with 15 mL of 2% mepivacaine. They were then randomly allocated in a double-blinded fashion to receive a sciatic nerve block with either 0.5% levobupivacaine (n = 25) or 0.5% ropivacaine (n = 25). An independent blinded observer evaluated the onset time of surgical anesthesia as well as the quality of the surgical block and postoperative analgesia. The median (range) onset time of surgical block at the sciatic nerve distribution was 30 min (5-60 min) with levobupivacaine and 15 min (5-60 min) with ropivacaine (P = 0.63). Four patients (two patients in each group) received a supplementary ankle block by the surgeon just before the beginning of surgery. All four patients also received IV fentanyl supplementation, but in three of them, propofol infusion was required to complete surgery (two in the Levobupivacaine group [8%] and one in the Ropivacaine group [4%]; P = 0.99). In six patients of the Levobupivacaine group (24%) and five patients of the Ropivacaine group (20%), IV fentanyl supplementation was required to complete surgery (P = 0.99). No differences in the time to recovery of sensory and motor function were observed between the two groups, whereas median (range) duration of postoperative analgesia was 16 h (8-24 h) with levobupivacaine and 16 h (8-24 h) with ropivacaine (P = 0.83). We conclude that 0.5% levobupivacaine and 0.5% ropivacaine provide comparable surgical anesthesia and postoperative analgesia. ⋯ No studies have compared the clinical properties of levobupivacaine with those of ropivacaine when providing sciatic nerve block for hallux valgus repair. Results from this prospective, randomized, double-blinded study demonstrate that 20 mL of either 0.5% levobupivacaine or 0.5% ropivacaine provide comparable surgical block with prolonged postoperative analgesia.