Combined spinal-epidural analgesia in labour: comparison of two doses of intrathecal bupivacaine with fentanyl.
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We have compared intrathecal bupivacaine 1.25 mg and fentanyl 25 micrograms (group A) with bupivacaine 2.5 mg and fentanyl 25 micrograms (group B), for combined spinal-epidural analgesia in 49 labouring parturients in a prospective, randomized, double-blind study. Onset and quality of analgesia were similar in both groups, with median visual analogue scale pain scores of 0 achieved in 5-10 min. Median duration of analgesia was longer in group B (median 120 (range 90-120) min) compared with group A (75 (75-105) min) (P = 0.013). Median upper sensory level was higher in group B compared with group A at 15 min (T6-7 vs T11, P = 0.003) and at 30 min (T6 vs T11-12; P = 0.001). Motor block was greater in group B: seven patients had a modified Bromage score > or = 1 compared with none in group A at 15 min (P = 0.017). Group B also had a greater decrease in arterial pressure. Patient-midwife satisfaction scores and other side effects were similar. We conclude that intrathecal bupivacaine 1.25 mg with fentanyl 25 micrograms provided analgesia of similar onset and quality compared with bupivacaine 2.5 mg and fentanyl 25 micrograms. Although the duration of analgesia was shorter, the incidences of motor block and hypotension were less with the smaller dose. (+info)
Oxidative metabolism of bupivacaine into pipecolylxylidine in humans is mainly catalyzed by CYP3A.
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Bupivacaine is used to provide prolonged anesthesia and postoperative analgesia. The human cytochrome P450 (CYP) involved in bupivacaine degradation into pipecolylxylidine (PPX), its major metabolite, has, to our knowledge, never been described. Microsome samples were prepared from six human livers and incubated in the presence of bupivacaine. The concentrations of PPX in the microsomal suspensions were assessed, and K(m) and V(max) values were calculated. Bupivacaine incubations were then performed with specific CYP substrates and inhibitors. For each sample of hepatic microsomes, the correlation between the rate of PPX formation and the corresponding erythromycin N-demethylase activity was analyzed. Finally, an immunoinhibition study using an anti-rabbit CYP3A6 antibody and assays with cDNA-expressed human CYP were conducted. The apparent K(m) and V(max) values of bupivacaine were, respectively, 125 microM and 4.78 nmol/min/mg of microsomal protein. The strongest inhibition of bupivacaine metabolism was obtained for troleandomycin (-95% at 50 microM), a specific CYP3A inhibitor. The correlation between PPX formation and erythromycin N-demethylase activity showed an R value of 0.99 whereas anti-rabbit CYP3A6 antibody inhibited the degradation of bupivacaine into PPX by 99%. Finally, CYP1A2 and CYP2E1 cDNA-expressed forms of human CYP did not allow PPX formation, CYP2C19 and CYP2D6 produced only small amounts whereas CYP3A4 most efficiently metabolized bupivacaine into PPX. These results demonstrated that bupivacaine degradation into PPX was mediated in humans by CYP3A. (+info)
Hyperbaric bupivacaine for spinal anaesthesia in 7-18 yr old children: comparison of bupivacaine 5 mg ml-1 in 0.9% and 8% glucose solutions.
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We have compared two hyperbaric bupivacaine solutions for spinal anaesthesia in 7-18-yr-old school-aged children in a double-blind, randomized, parallel group, prospective study. Children were premedicated with diazepam orally. Half of the patients were sedated with either midazolam or thiopental. After lumbar puncture with a 27-gauge spinal needle, bupivacaine 5 mg ml-1 in either 0.9% or 8% glucose was injected in a dose of 0.3 mg kg-1. Maximum cephalad spread and regression of block were tested by transcutaneous electrical stimulation. Success rate, spread and duration of sensory block were similar in both groups. The highest median level of sensory block was T4 (10-90th percentiles T1-T7) in the 0.9% glucose group and T4 (T1-T5) in the 8% glucose group. Time to two segment regression of block was 83 (50-143) min in the 0.9% glucose and 85 (53-150) min in the 8% glucose group. The incidence of adverse effects was similar. Six children were given etilefrin to treat hypotension and six atropine for bradycardia. Nausea was associated with a high level of block. Shivering was detected in 16 children. (+info)
Wound infiltration with bupivacaine after surgery to the cervical spine using a posterior approach.
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We have compared pain scores, morphine consumption and duration of stay for 50 adults who underwent elective cervical spine surgery via a posterior incision in a prospective, double-blind, placebo-controlled, randomized study. During wound closure, the paravertebral muscles and subcutaneous tissues were infiltrated with 40 ml of saline (control) or 0.25% bupivacaine. There were no significant differences in pain scores, morphine consumption or duration of stay between groups. In view of the potential risks of wound infiltration in the cervical region, we consider that this practice should be abandoned. (+info)
Comparison of 1% ropivacaine with 0.75% bupivacaine and 2% lidocaine for peribulbar anaesthesia.
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We have compared the efficacy of 1% ropivacaine with a mixture of 0.75% bupivacaine and 2% lidocaine for peribulbar anaesthesia in cataract surgery. We used the time to adequate block for surgery, and ocular and eyelid movement scores at 8 min after block as clinical end-points. Ninety patients were allocated randomly to receive 7-10 ml of a mixture of equal parts of 0.75% bupivacaine and 2% lidocaine or an equal volume of 1% ropivacaine alone. Hyaluronidase 15 iu ml-1 was added to both solutions. There were no differences between groups in clinical end-points. Median time at which the block was adequate to start surgery was 8 min (interquartile range 4-10 min) in each group. Median eyelid movement scores were similar in both groups, but the bupivacaine and lidocaine mixture produced a significantly decreased ocular movement score at 2, 4 and 6 min (P < 0.05). There was no difference between groups in the incidence of minor complications. Based on clinical end-points, time to adequate block for surgery and median ocular and eyelid movement scores at 8 min, 1% ropivacaine as the sole agent for peribulbar anaesthesia was comparable with a mixture of 0.75% bupivacaine and 2% lidocaine. (+info)
Effect of continuous epidural 0.2% ropivacaine vs 0.2% bupivacaine on postoperative pain, motor block and gastrointestinal function after abdominal hysterectomy.
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We have investigated the effect of 24-h postoperative continuous epidural infusion of 0.2% ropivacaine or 0.2% bupivacaine 8 ml h-1 on pain, request for supplementary analgesics, motor block and gastrointestinal function, in a double-blind, randomized study in 60 patients undergoing open hysterectomy. There were no significant differences between groups in pain, number of patients requesting supplementary analgesics, motor block, ability to walk or time to first flatus or stool. In the subgroup of patients who received supplementary analgesics, patients in the ropivacaine group received significantly more ketorolac than patients in the bupivacaine group. Time to discharge from hospital was similar with ropivacaine and bupivacaine. (+info)
Infiltration of the abdominal wall with local anaesthetic after total abdominal hysterectomy has no opioid-sparing effect.
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We have measured the effect of infiltration of the deep and superficial layers of the abdominal wound on morphine consumption and pain for 48 h after operation, in 40 patients undergoing total abdominal hysterectomy, in a double-blind randomized study. Patients received wound infiltration with 0.9% normal saline 40 ml or 40 ml of 0.25% bupivacaine with epinephrine 1:200,000. There were no significant differences between groups in morphine consumption, linear analogue scores for pain at rest or on movement, nausea or sedation during the first 48 h after operation. We conclude that infiltration of the deep and superficial layers of the wound of a Pfannenstiel incision with local anaesthetic solution did not confer additional analgesia in patients undergoing major gynaecological surgery. (+info)
Maximum tolerated dose of nalmefene in patients receiving epidural fentanyl and dilute bupivacaine for postoperative analgesia.
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BACKGROUND: This study investigated the ability of the modified continual reassessment method (MCRM) to determine the maximum tolerated dose of the opioid antagonist nalmefene, which does not reverse analgesia in an acceptable number of postoperative patients receiving epidural fentanyl in 0.075% bupivacaine. METHODS: In the postanesthetic care unit, patients received a single intravenous dose of 0.25, 0.50, 0.75, or 1.00 microg/kg nalmefene. Reversal of analgesia was defined as an increase in pain score of two or more integers above baseline on a visual analog scale from 0 through 10 after nalmefene administration. Patients were treated in cohorts of one, starting with the lowest dose. The maximum tolerated dose of nalmefene was defined as that dose, among the four studied, with a final mean probability of reversal of anesthesia (PROA) closest to 0.20 (ie., a 20% chance of causing reversal). The modified continual reassessment method is an iterative Bayesian statistical procedure that, in this study, selected the dose for each successive cohort as that having a mean PROA closest to the preselected target PROA of 0.20. RESULTS: The modified continual reassessment method repeatedly updated the PROA of each dose level as successive patients were observed for presence or absence of ROA. After 25 patients, the maximum tolerated dose of nalmefene was selected as 0.50 microg/kg (final mean PROA = 0.18). The 1.00-microg/kg dose was never tried because its projected PROA was far above 0.20. CONCLUSIONS: The modified continual reassessment method facilitated determination of the maximum tolerated dose ofnalmefene . Operating characteristics of the modified continual reassessment method suggest it may be an effective statistical tool for dose-finding in trials of selected analgesic or anesthetic agents. (+info)