Preemptive analgesia by intravenous low-dose ketamine and epidural morphine in gastrectomy: a randomized double-blind study.
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BACKGROUND: Morphine and ketamine may prevent central sensitization during surgery and result in preemptive analgesia. The reliability of preemptive analgesia, however, is controversial. METHODS: Gastrectomy patients were given preemptive analgesia consisting of epidural morphine, intravenous low-dose ketamine, and combinations of these in a randomized, double-blind manner. Postsurgical pain intensity was rated by a visual analog scale, a categoric pain evaluation, and cumulative morphine consumption. RESULTS: Preemptive analgesia by epidural morphine and by intravenous low-dose ketamine were significantly effective but not definitive. With epidural morphine, a significant reduction in visual analog scale scores at rest was observed at 24 and 48 h, and morphine consumption was significantly lower at 6 and 12 h, compared with control values. With intravenous ketamine, visual analog scale scores at rest and morphine consumption were significantly lower at 6, 12, 24, and 48 h than those in control subjects. The combination of epidural morphine and intravenous ketamine provided definitive preemptive analgesia: Visual analog scale scores at rest and morphine consumption were significantly the lowest at 6, 12, 24, and 48 h, and the visual analog scale score during movement and the categoric pain score also were significantly the lowest among the groups. CONCLUSION: The results suggest that for definitive preemptive analgesia, blockade of opioid and N-methyl-d-aspartate receptors is necessary for upper abdominal surgery such as gastrectomy; singly, either treatment provided significant, but not definitive, postsurgical pain relief. Epidural morphine may affect the spinal cord segmentally, whereas intravenous ketamine may block brain stem sensitization via the vagus nerve during upper abdominal surgery. (+info)
Lumbar plexus block reduces pain and blood loss associated with total hip arthroplasty.
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BACKGROUND: The usefulness of peripheral nerve blockade in the anesthetic management of hip surgery has not been clearly established. Because sensory afferents from the hip include several branches of the lumbar plexus, the authors hypothesized that a lumbar plexus block could reduce pain from a major hip procedure. METHODS: In a double-blind prospective trial, 60 patients undergoing total hip arthroplasty were randomized to receive general anesthesia with (plexus group, n = 30) or without (control group, n = 30) a posterior lumbar plexus block. The block was performed after induction using a nerve stimulator, and 0.4 ml/kg bupivacaine, 0.5%, with epinephrine was injected. General anesthesia was standardized, and supplemental fentanyl was administered per hemodynamic guidelines. Postoperative pain and patient-controlled intravenous morphine use were serially assessed for 48 h. RESULTS: The proportion of patients receiving supplemental fentanyl intraoperatively was more than 3 times greater in the control group (20 of 30 vs. 6 of 29, P = 0.001). In the postanesthesia care unit, a greater than fourfold reduction in pain scores was observed in the plexus group (visual analogue scale [VAS] pain score at arrival 1.3 +/- 2 vs. 5.6 +/- 3, P < 0.001), and "rescue" morphine boluses (administered if VAS > 3) were administered 10 times less frequently (in 2 of 28 vs. in 22 of 29 patients, P < 0.0001). Pain scores and morphine consumption remained significantly lower in the plexus group until 6 h after randomization (VAS at 6 h, 1.4 +/- 1.3 vs. 2.4 +/- 1.4, P = 0.007; cumulative morphine at 6 h, 5.6 +/- 4.7 vs. 12.6 +/- 7.5 mg, P < 0.0001). Operative and postoperative (48 h) blood loss was modestly decreased in the treated group. Epidural-like distribution of anesthesia occurred in 3 of 28 plexus group patients, but no other side-effects were noted. CONCLUSIONS: Posterior lumbar plexus block provides effective analgesia for total hip arthroplasty, reducing intra- and postoperative opioid requirements. Moreover, blood loss during and after the procedure is diminished. Epidural anesthetic distribution should be anticipated in a minority of cases. (+info)
Epidural infusion of ropivacaine for postoperative analgesia after major orthopedic surgery: pharmacokinetic evaluation.
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BACKGROUND: Changing plasma protein concentrations may affect the protein binding and pharmacokinetics of drugs in the postoperative phase. Therefore, the authors evaluated the pharmacokinetics of ropivacaine, administered by 72-h epidural infusion to provide postoperative analgesia. METHODS: Twenty-eight patients, scheduled for major orthopedic surgery during combined epidural and general anesthesia received a bolus dose of ropivacaine (50 or 75 mg), followed by constant-rate (10 ml/h) epidural infusion of ropivacaine 2 mg/ml (group 1) or 3 mg/ml (group 2). Total and unbound plasma concentrations of ropivacaine and pipecoloxylidide and plasma concentrations of alpha1-acid glycoprotein were determined. In addition, the urinary excretion of ropivacaine and major metabolites was measured. RESULTS: Total plasma concentrations of ropivacaine increased steadily during the infusion, reaching 2.7 +/- 0.7 and 2.9 +/- 0.5 mg/l in groups 1 and 2 after 72 h constant-rate infusion. Unbound ropivacaine concentrations reached average steady state levels of approximately 0.06 and 0.07 mg/l. Total and unbound concentrations of pipecoloxylidide increased to 1.0 +/- 0.4 and 0.4 +/- 0.2 mg/l (group 1) and 1.2 +/- 0.4 and 0.5 +/- 0.1 mg/l (group 2) after 72 h infusion. alpha1-Acid glycoprotein concentrations initially decreased, but thereafter increased steadily to approximately twice the baseline values. CONCLUSIONS: Postoperative increases in plasma alpha1-acid glycoprotein concentrations enhance the protein binding of ropivacaine and pipecoloxylidide, causing divergence of total and unbound plasma concentrations. (+info)
BACKGROUND: Rapid development of acute opioid tolerance is well established in animals and is more likely to occur with large doses of short-acting drugs. The authors therefore tested the hypothesis that intraoperative remifentanil administration results in acute opioid tolerance that is manifested by increased postoperative pain and opioid requirement. METHODS: Fifty adult patients undergoing major abdominal surgery were randomly assigned to two anesthetic regimens: (1) desflurane was kept constant at 0.5 minimum alveolar concentrations and a remifentanil infusion was titrated to autonomic responses (remifentanil group); or (2) remifentanil at 0.1 microg. kg-1. min-1 and desflurane titrated to autonomic responses (desflurane group). All patients were given a bolus of 0.15 mg/kg morphine 40 min before the end of surgery. Morphine was initially titrated to need by postanesthesia care nurses blinded to group assignment. Subsequently, patients-who were also blinded to group assignment-controlled their own morphine administration. Pain scores and morphine consumption were recorded for 24 postoperative h. RESULTS: The mean remifentanil infusion rate was 0.3 +/- 0.2 microg. kg-1. min-1 in the remifentanil group, which was significantly greater than in the desflurane group. Intraoperative hemodynamic responses were similar in each group. Postoperative pain scores were significantly greater in the remifentanil group. These patients required morphine significantly earlier than those in the desflurane group and needed nearly twice as much morphine in the first 24 postoperative h: 59 mg (25-75% interquartile range, 43-71) versus 32 mg (25-75% interquartile range, 19-59; P < 0.01). CONCLUSIONS: Relatively large-dose intraoperative remifentanil increased postoperative pain and morphine consumption. These data suggest that remifentanil causes acute opioid tolerance and hyperalgesia. (+info)
Age is not an impediment to effective use of patient-controlled analgesia by surgical patients.
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BACKGROUND: Obstacles to the use of patient-controlled analgesia (PCA) by elderly surgical patients have not been well-documented. Age differences in preoperative psychological factors, postoperative pain and analgesic consumption, treatment satisfaction, and concerns regarding PCA were measured to identify factors important to effective PCA use. METHODS: Preoperatively, young (mean age +/- SD, 39 +/- 9 yr; n = 45) and older (mean age +/- SD, 67 +/- 8 yr; n = 44) general surgery patients completed measures of attitudes toward and expectations of postoperative pain and PCA, psychological distress, health opinions, self-efficacy, and optimism. On the first 2 postoperative days, pain at rest and with movement and satisfaction with pain control were assessed using visual analog scales. Daily opioid intake was recorded. When PCA was discontinued, satisfaction and concerns about it were assessed. RESULTS: The older patients expected less intense pain (P +info)
Use of intravenous patient-controlled analgesia for the documentation of synergy between tramadol and metamizol.
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The quantification of the synergistic interactions (beneficial and adverse) of analgesic drug combinations in humans has been elusive. We propose a new procedure based on analgesic requirements (i.v.-PCA) and pain intensity (VAS-PI). One hundred and one post-hysterectomy patients received at the time of analgesia request (TAR) tramadol (100 mg, group I) or metamizol (1.2 g, group II) alone, or combined in 1:1 (III), 1:0.3 (IV) or 1:3 ratio (V). After 15 min, they received the same treatment by PCA. VAS-PI, analgesic consumption and adverse effects were assessed at TAR, and periodically for 24 h. Data were analysed using interaction indexes and isobolograms. All treatments produced equivalent VAS-PI, per cent efficacy and adverse effects. When drugs were combined in a 1:1 ratio, synergy was present for the analgesic and adverse effects; all other treatments were additive. (+info)
Efficacy and respiratory effects of low-dose spinal morphine for postoperative analgesia following knee arthroplasty.
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A randomized, double-blind study of 38 patients undergoing total knee replacement was undertaken to compare the efficacy and respiratory effects of low-dose spinal morphine and patient-controlled i.v. morphine against patient-controlled i.v. morphine alone. Patients received either morphine 0.3 mg or saline 0.3 ml with 0.5% heavy spinal bupivacaine 2-2.5 ml. Respiratory effects were measured continuously for 14 h postoperatively with an Edentec 3711 respiratory monitor. There was an improvement in pain relief in the intrathecal morphine group, with significantly lower median VAS pain scores on movement at 4 h (0 (median 0-1.5) vs 5 (1.25-7.75) P < 0.01), 12 h (2 (1-5) vs 6 (3-8) P < 0.01) and 24 h (3 (1-5) vs 5 (3-7) P < 0.05) postoperatively, despite using significantly less patient-controlled morphine (20 mg (10.25-26.25) vs 38.5 mg (27-51) P < 0.01) in the first 24 h. There was a small but statistically significant reduction in the median oxygen saturation (SpO2) in the intrathecal morphine group 97 (95-99)% compared with the placebo group 99 (97-99)% (P < 0.05). Although marked disturbances in respiratory pattern were observed in both groups, none of the patients in the study had severe hypoxaemia (SpO2 < 85% > 6 min h-1) and there was no significant difference in the incidence of mild (SpO2 < 94% > 12 min h-1) or moderate (SpO2 < 90% > 12 min h-1) hypoxaemia or in the incidence of episodes of apnoea or hypopnoea in the two groups. (+info)
Fentanyl versus sufentanil: plasma concentrations during continuous epidural postoperative infusion in children.
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No pharmacokinetic data are available with respect to the plasma concentrations and fentanyl or sufentanil during epidural administration in children. This double-blind randomized study included 12 children (5-12 yr). Patients in group F were given an epidural loading dose of fentanyl 1.5 micrograms kg-1 and in group S sufentanil 0.6 microgram kg-1. Both groups then received a continuous epidural infusion of bupivacaine 5 mg kg-1 day-1 with either fentanyl 5 micrograms kg-1 day-1 or sufentanil 2 micrograms kg-1 day-1. An epidural PCA system was also given to the children (bolus: bupivacaine 0.2 mg kg-1 and fentanyl 0.2 microgram kg-1 or sufentanil 0.08 microgram kg-1). Maximal median concentrations of plasma (0.117-0.247 ng ml-1 for fentanyl and 0.027-0.074 ng ml-1 for sufentanil) were reached approximately 30 and 20 min respectively after the loading doses. These values were similar to those measured after 48 h. (+info)