Ropivacaine plasma concentrations during 120-hour epidural infusion

Evaluation of analgesic effects and hemodynamic responses of epidural ropivacaine in laparoscopic abdominal surgeries: Randomised controlled trial

Background and Aims:

The role of epidural analgesia in laparoscopic surgeries remains controversial. We evaluated intraoperative analgesic effects of epidural ropivacaine versus intravenous fentanyl in laparoscopic abdominal surgery and assessed postoperative analgesic requirements, hemodynamic changes, time to ambulation, and length of stay (LOS) in the ICU.

Material and Methods:

Seventy-two American Society of Anesthesiologists physical status I–III adult patients undergoing elective laparoscopic abdominal surgeries were randomized to either 0.5 mg/kg/h intravenous fentanyl (Group C) or 0.2% epidural ropivacaine at 5–8 mL/h (Group E) infusions intraoperatively and 0.25 m/kg/h fentanyl and 0.1% epidural ropivacaine infusions respectively postoperatively. Variations in mean arterial pressure (MAP) of 20% from baseline were points of intervention for propofol and analgesia with fentanyl or vasopressors. The number of interventions and total doses of fentanyl and vasopressors were noted. Postoperative analgesia was assessed at 0, 6, 12, and 24 h and when pain was reported with numerical rating scale and objective pain scores. Chi-square test and Student’s t-test were used for categorical and continuous variable analysis.

Results:

Intraoperatively, 14 patients versus 4 needed additional fentanyl and 26 versus 14 needed additional propofol in groups C and E respectively (P = 0.007, P = 0.004). MAP at 0, 6 and 18 h was lower in Group E. Pain scores were better in Group E at 6,18, and 24 h postoperatively. Time to ambulation was comparable but LOS ICU was prolonged in Group E (P = 0.05)

Conclusion:

Epidural ropivacaine produces superior intraoperative analgesia and improved postoperative pain scores without affecting ambulation but increases vasopressor need and LOS ICU in comparison with intravenous fentanyl in laparoscopic abdominal surgeries.

Comparative study of the influence of adductor canal block plus multimodal periarticular infiltration versus combined adductor canal block, multimodal periarticular infiltration and intra-articular epidural catheter ropivacaine infiltration on pain relief after total knee arthroplasty: a prospective study

BACKGROUND

A combined regimen of adductor canal block (ACB) and multimodal periarticular infiltration (MPI) with local anesthetic (ropivacaine) is a known effective method of controlling pain in the first 6-8 h after total knee arthroplasty (TKA); however, managing breakthrough pain after their combined effect wears off can be challenging. We hypothesized that, by additionally leaving an intra-articular epidural catheter (IAEC) inside the knee with intermittent infiltration of local anesthetic in conjunction with ACB and MPI, it would help manage the breakthrough pain when their combined effect wears off.

METHODS

We did a prospective study in our institution between December 2015 and August 2016 on a total of 206 patients undergoing primary unilateral TKA. The initial consecutive 106 patients received ACB + MPI (Group 1, n = 106), and the subsequent 100 patients received ACB + MPI + IAEC (Group 2, n = 100). The primary outcome measure was pain using visual analogue scale (VAS) recorded at 6, 12, 24 and 48 h, and the secondary outcome measures were requirement for rescue analgesics and repeat adductor canal block and length of hospital stay.

RESULTS

There was no statistically significant difference in VAS scores between the two groups at 6 h but at 12, 24 and 48 h; there was a statistically significant difference between the two groups in terms of VAS scores, rescue analgesic requirements, repeat adductor canal block and shorter hospital stay favoring the ACB + MPI + IAEC group.

CONCLUSION

Intermittent knee infiltration with ropivacaine is a safe, reproducible and effective method to control pain in the first 48 h postoperative period after TKA.

Ropivacaine via nuclear factor kappa B signalling modulates CD62E expression and diminishes tumour cell arrest

BACKGROUND

The issue whether anaesthesia has an impact on the prognosis of carcinoma has been widely discussed and remains debated. Ropivacaine has been widely used in perioperative period as a long acting local anesthetic. An early event during recurrence or metastasis of carcinoma is the adhesion of circulating tumour cells (CTCs) to endothelial cells (ECs) through binding adhesion molecules that are up-regulated on inflamed endothelium during the perioperative period or other periods. This study was to explore the impact of ropivacaine on the adhesion of tumour cells, providing evidences of its influence on the prognosis of carcinoma.

MATERIALS AND METHODS

Human umbilical vein endothelial cells (HUVECs) were pre-treated with ropivacaine (10^-7-10^-5 M; 30 min) prior to treatment with tumour necrosis factor alpha (TNFα) (10 ng ml^-1; 1, 4 and 8 h). Intercellular adhesion molecule-1 (ICAM-1), endothelial-selectin (CD62E) and vascular cell adhesion molecule-1 (VCAM-1) mRNA levels were detected via quantitative reverse-transcriptase polymerase chain reaction (qRT-PCR). To clarify the underlying action mechanism, p65, p-p65, IκBα, p-IκBα, IKKα/β and p-IKKα/β protein levels were evaluated via western blotting. Cell viability and tumour cell adhesion assays were also assessed.

RESULTS

The clinically usage concentration of ropivacaine (10^-6 M) produced a significant decrease in CD62E expression compared with that produced by TNFα only (p < 0.001). Moreover, adhesion assays showed that ropivacaine effectively inhibited the adhesion of hepatoma cells (p < 0.01), human colon cancer cells (p < 0.01) and human leukemic monocyte (p < 0.01). Western blot results showed that pre-treatment with ropivacaine inhibited the phosphorylation of p65 (p < 0.05), IκBα (p < 0.001) and IKKα/β (p < 0.01).

CONCLUSIONS

Ropivacaine decreased the adhesion of tumour cells. Ropivacaine modulated CD62E expression by inhibiting the activation of NF-κB. These results might provide new insight into the issue whether anaesthesia has an impact on the prognosis of carcinoma.

Effect of lidocaine and ropivacaine on primary (SW480) and metastatic (SW620) colon cancer cell lines

Regional anesthesia may prolong survival following surgery for different types of cancers. The mechanisms behind this are unclear but direct effects on cancer cells by local anesthetics (LA) have been suggested. The aim of this study was to investigate if lidocaine or ropivacaine have a dose-dependent effect on the cell viability and proliferation of a primary and a secondary colon carcinoma cell line in vitro. The colon cancer cell lines SW480 derived from primary tumor and SW620 from a metastatic site in the same patient were exposed to increasing concentrations of lidocaine and ropivacaine (5-1,000 µM). Cell viability was measured using CellTiter-Blue^® and cell proliferation by PKH67 after exposure for up to 72 h. Cell viability was significantly reduced by ropivacaine at the highest concentration (1,000 µM) after 48 and 72 h in the cell line SW480 and at 72 h in SW620. Exposure to lidocaine did not show any significant reduction in cell viability. Notably, low concentrations of both lidocaine and ropivacaine significantly increased cell viability after 48 and 72 h in SW620. Cell proliferation was significantly reduced by 1,000 µM lidocaine in SW480 and by 1,000 µM ropivacaine in SW620. In summary, both lidocaine and ropivacaine showed an anti-proliferative effect in the colon cancer cell lines at high concentrations and after prolonged exposure to LA in vitro. Our findings also indicate that lower concentrations promote cell viability in the metastatic cell line.

Bilateral sternal infusion of ropivacaine and length of stay in ICU after cardiac surgery with increased respiratory risk: A randomised controlled trial

BACKGROUND

The continuous bilateral infusion of a local anaesthetic solution around the sternotomy wound (bilateral sternal) is an innovative technique for reducing pain after sternotomy.

OBJECTIVE

To assess the effects of the technique on the need for intensive care in cardiac patients at increased risk of respiratory complications.

DESIGN

Randomised, observer-blind controlled trial.

SETTING

Single centre, French University Hospital.

PATIENTS

In total, 120 adults scheduled for open-heart surgery, with one of the following conditions: age more than 75 years, BMI >30 kg m, chronic obstructive pulmonary disease, active smoking habit.

INTERVENTION

Either a bilateral sternal infusion of 0.2% ropivacaine (3 ml h through each catheter; 'intervention' group), or standardised care only ('control' group). Analgesia was provided with paracetamol and self-administered intravenous morphine.

MAIN OUTCOME MEASURES

The length of time to readiness for discharge from ICU, blindly assessed by a committee of experts.

RESULTS

No effect was found between groups for the primary outcome (P = 0.680, intention to treat); the median values were 42.4 and 37.7 h, respectively for the control and intervention groups (P = 0.873). Similar nonsignificant trends were noted for other postoperative delays. Significant effects favouring the intervention were noted for dynamic pain, patient satisfaction, occurrence of nausea and vomiting, occurrence of delirium or mental confusion and occurrence of pulmonary complications. In 12 patients, although no symptoms actually occurred, the total ropivacaine plasma level exceeded the lowest value for which neurological symptoms have been observed in healthy volunteers.

CONCLUSION

Because of a small size effect, and despite significant analgesic effects, this strategy failed to reduce the time spent in ICU.

TRIAL REGISTRATION

EudraCT (N°: 2012-005225-69); ClinicalTrials.gov (NCT01828788).

Local infiltration analgesia in knee and hip arthroplasty efficacy and safety

Background

This is a secondary publication of a PhD thesis. Local infiltration analgesia (LIA) is a new multimodal wound infiltration method for treating postoperative pain after knee and hip arthroplasty. This method is based on systematic infiltration of a mixture of ropivacaine, a long acting local anaesthetic, ketorolac, a cyclooxygenase inhibitor (NSAID), and adrenalin around all structures subject to surgical trauma in knee and hip arthroplasty.

Aims

Paper I: to assess whether pain relief after LIA in total knee arthroplasty (TKA) is as effective as femoral block. Paper II: to assess whether the plasma concentration of ropivacaine and ketorolac after LIA in TKA reaches levels linked to toxicity. Paper III: to assess whether the plasma concentration of unbound ropivacaine after LIA in THA reaches levels linked to toxicity and if it is higher in THA as compared to TKA. Paper IV: to assess whether the plasma concentration of ketorolac after LIA in THA reaches levels linked to toxicity, and whether administration of ketorolac in LIA is safer as compared to the intramuscular route.

Methods

Two patient cohorts of 40 patients scheduled for elective total knee arthroplasty (TKA) and 15 patients scheduled for total hip arthroplasty (THA) contributed to this work. In a randomized trial the efficacy of LIA in TKA with regard to pain at rest and upon movement was compared to femoral block.

Results

Both methods result in a high quality pain relief and similar morphine consumption during the 24 h monitoring period. In the same patient cohort the maximal total plasma concentration of ropivacaine was below the established toxic threshold for most patients. All patients in the THA cohort were subjected to the routine LIA protocol. In these patients both the total and unbound plasma concentration of ropivacaine was determined. The concentration was below the established toxic threshold. As ropivacaine binds to α–1 acid glycoprotein (AAG) we assessed the possibility that increased AAG may decrease the unbound concentration of ropivacaine. A 40% increase in AAG was detected during the first 24 h after surgery, however the fraction of unbound ropivacaine remained the same. There was a trend towards increased C max of ropivacaine with increasing age and decreasing creatinine clearance but the statistical power was too low to draw any conclusion. Administration of 30 mg ketorolac according to the LIA protocol both in TKA and THA resulted in a similar C max as previously reported after 10 mg intramuscular ketorolac. Neither age, nor body weight or BMI, nor creatinine clearance, correlates to maximal ketorolac plasma concentration or total exposure to ketorolac (AUC).

Conclusion

LIA provides good postoperative analgesia which is similar to femoral block after total knee arthroplasty. The plasma concentration of ropivacaine seems to be below toxic levels in most TKA patients. The unbound plasma concentration of ropivacaine in THA seems to be below the toxic level.

Implication

The use of ketorolac in LIA may not be safer than other routes of administration, and similar restrictions should be applied in patients at risk of developing side effects.

Effects of ropivacaine, bupivacaine and sufentanil in colon and pancreatic cancer cells in vitro

The perioperative period is supposed to be a vulnerable period for cancer progression. Results of clinical studies indicate that the use of regional anesthesia can influence and improve oncological outcome of cancer patients. Uncontrolled cell proliferation and resistance to apoptotic cell death are important characteristics of solid tumors. The aim of this study was to investigate the effects of the clinically used local anesthetics ropivacaine or bupivacaine and the opioid analgesic sufentanil on cell proliferation, cell cycle distribution and apoptosis of colon (HT 29 and SW 480) and pancreatic (PaTu 8988t and PANC 1) cancer cell lines in vitro. Cell proliferation was measured by Cell Proliferation ELISA BrdU Assay. Apoptosis was analyzed by annexin V staining and cell cycle distribution was detected by flow cytometry. Ropivacaine, bupivacaine and sufentanil did not change apoptosis rate and cell cycle distribution in clinically concentration. Only high concentrations of ropivacaine or bupivacaine revealed antiproliferative potency. Protective effects of epidural anesthesia observed in clinical studies seem not to be based on direct effects of these drugs on cancer cells.

[Interaction of anesthetics and analgesics with tumor cells]

The results of preclinical and clinical studies indicate that the perioperative period is a vulnerable period for cancer progression and metastasis. The risk of cancer cell dissemination is enhanced by the combination of surgical manipulation and perioperative immunosuppression. Whether the oncological outcome of cancer patients can be influenced by the choice of anesthetic techniques is still a matter of debate. This review summarizes the molecular characteristics of cancer and interaction of anesthetic and analgesic drugs with cancer cells.

Ropivacaine pharmacokinetics after local infiltration analgesia in hip arthroplasty

In this study, we determined the plasma concentration of ropivacaine by liquid chromatography-mass spectrometry for 30 hours after local infiltration analgesia in 15 patients with elective hip arthroplasty. The 95% upper prediction bound of maximal unbound plasma concentration of ropivacaine was 0.032 mg/L. Side effects sufficient to stop an IV infusion have been reported at arterial concentrations of 0.34 to 0.85 mg/L. Alpha-1-acid glycoprotein did not correlate with the fraction of unbound ropivacaine during the first 24 hours after local infiltration analgesia. No signs or symptoms of systemic local anesthetic toxicity were observed. The Clopper-Pearson 95% upper confidence limit for adverse signs was 0.218.

The analgesic effects of a bilateral sternal infusion of ropivacaine after cardiac surgery

BACKGROUND AND OBJECTIVES

The aim of this study was to assess the effects of a continuous postoperative administration of local anesthetic through 2 catheters placed deeply under fascia at the lateral edges of the sternum, close to the emergence of the intercostal nerves. We focused on pain during mobilization, as this aspect is likely to interact with postoperative morbidity.

METHODS

Forty adult patients scheduled for open heart surgery with sternotomy were included in this randomized, placebo-controlled, double-blind study. A continuous fixed-rate infusion of 4 mL/hr of 0.2% ropivacaine or normal saline was administered during the first 48 postoperative hrs. All patients received acetaminophen and self-administered morphine. The efficacy outcomes were as follows: pain score during standardized mobilization and at rest; morphine consumption; spirometry and arterial blood gases; postoperative rehabilitation criteria, and patient satisfaction. Total ropivacaine plasma level was monitored throughout the study.

RESULTS

Pain scores were lower in the ropivacaine group during mobilization (P = 0.0004) and at rest (P = 0.0006), but the analgesic effects were mostly apparent during the second day after surgery, with a 41% overall reduction in movement-evoked pain levels. The bilateral sternal block also reduced morphine consumption. It improved the patients' satisfaction and rehabilitation, but no effects were noted on respiratory outcomes. No major adverse effect due to the treatment occurred, but the ropivacaine plasma level was greater than 4 mg/L in 1 patient.

CONCLUSIONS

This technique may find a role within the framework of multimodal analgesia after sternotomy, although further confirmatory studies are needed.

Autologous blood transfusion after local infiltration analgesia with ropivacaine in total knee and hip arthroplasty

Aims. To study the safety of autotransfusion following local infiltration analgesia (LIA) with ropivacaine. Background. Knowledge of blood concentrations of ropivacaine after LIA and autotransfusion is crucial. However, very limited data are available for toxicological risk assessment. Methods. Autotransfusion was studied in patients after total knee arthroplasty (TKA: n = 25) and total hip arthroplasty (THA: n = 27) with LIA using 200 mg ropivacaine, supplemented with two postoperative bolus injections (150 mg ropivacaine). Drainage blood was reinfused within 6 h postoperatively. Results. Reinfusion caused a significant increase in the serum concentration of total ropivacaine for TKA from 0.54 ± 0.17 (mean ± SD) to 0.79 ± 0.20 μg/mL (P < 0.001) and a nonsignificant increase for THA from 0.62 ± 0.17 to 0.63 ± 0.18 μg/mL. The maximum free (unbound) concentration after reinfusion was 0.038 μg/mL. Peak total and free venous ropivacaine concentrations after 8 h and 16 h postoperative bolus injections were 2.6 μg/mL and 0.11 μg/mL, respectively. All concentrations observed were below the threshold for toxicity and no side effects were observed. Conclusion. Autotransfusion of patients undergoing knee or hip arthroplasty after local infiltration analgesia with 200 mg ropivacaine can be performed safely, even supplemented with 8 h and 16 h postoperative bolus injections.

Local Infiltration Analgesia for Postoperative Pain Control following Total Hip Arthroplasty: A Systematic Review

Local infiltration analgesia (LIA) is an analgesic technique that has gained popularity since it was first brought to widespread attention by Kerr and Kohan in 2008. The technique involves the infiltration of a large volume dilute solution of a long-acting local anesthetic agent, often with adjuvants (e.g., epinephrine, ketorolac, an opioid), throughout the wound at the time of surgery. The analgesic effect duration can then be prolonged by the placement of a catheter to the surgical site for postoperative administration of further local anesthetic. The technique has been adopted for use for postoperative analgesia following a range of surgical procedures (orthopedic, general, gynecological, and breast surgeries). The primary objective of this paper was to determine, based on the current evidence, if LIA is superior when compared to no intervention, placebo, and alternative analgesic methods in patients following total hip arthroplasty, in terms of certain outcome measures. The outcomes considered were postoperative analgesia scores, joint function/rehabilitation, and length of hospital stay. Secondary objectives were to review available evidence and current knowledge regarding the pharmacokinetics of local anesthetic and adjuvant drugs when administered in this way and the occurrence of adverse events.

Involvement of α1-acid glycoprotein in inter-individual variation of disposition kinetics of ropivacaine following epidural infusion in off-pump coronary artery bypass grafting

The influence of drug interaction and protein variants on the binding disposition of ropivacaine to α1-acid glycoprotein (AGP) was examined. The subjects were five patients who received epidural infusion of ropivacaine for 24–54 h in off-pump coronary artery bypass grafting followed by drug combination therapy, and 10 healthy volunteers.

The post-operation plasma albumin concentration showed little overall change, while the AGP concentration in the five patients decreased for 6 h, then increased gradually to about 3-times the initial value by 54 h. The unbound fraction in plasma (fu) of ropivacaine gradually decreased as the AGP concentration increased, but there was large inter-individual variation among the five patients. In contrast, there was a good correlation between the fu value and AGP concentration when ropivacaine was added to blood samples from the 10 healthy volunteers. Among the volunteers, eight showed F1S variants and two showed F1 variant without S variant of AGP. The fu value of ropivacaine did not differ between these two groups. However, when ropivacaine was added in combination with dipyridamole, the fu values of ropivacaine in blood from volunteers with F1S variants were greater than those in blood from volunteers without S variant. In the case of co-administration of disopyramide or lidocaine, there was no such difference. Among the patients, one showed F1S variants and four showed F1 variant without S variant. The results indicate that variability in the side-effects of therapy with ropivacaine alone is caused by the change of the unbound concentration upon changes in the AGP concentration. However, in combination therapy, it is also important to consider the AGP variant-dependence of the inhibitory effect of concomitantly administered drugs.

Serum and wound drain ropivacaine concentrations after wound infiltration in joint arthroplasty

Ropivacaine blood and drain levels were measured in 20 hip and 15 total knee arthroplasties after intraoperative wound infiltration with 150 to 200 mL (360-400 mg) of ropivacaine, followed by a 48-hour intra-articular pain pump infusion of 1000 mg (knees) and 300 mg (hips) commencing 12 hours postoperatively. Concentrations were below 2 microg/mL over the first 12 hours before the pain pump increased levels. Peak total ropivacaine concentration ranged from 0.65 to 4.36 microg/mL with the pain pump. The high infiltration doses produced levels below or within the safe threshold of 1 to 3 microg/mL. Pain pump infusion produced some C(max) levels above 3.0 microg/mL, but there was no clinical evidence of toxicity. Wound drain amounts (0.53-26.69 mg) indicate reinfusion should be safe, although further study is needed to confirm this.

Safety of 96-Hour Incision-Site Continuous Infusion of Ropivacaine for Postoperative Analgesia After Bowel Cancer Resection

The aim of this study was to examine the safety of ropivacaine given to patients as a continuous infusion [0.2% (2 mg/mL), 5 mL/h for 96 hours] into a right lateral transverse incision using a portable elastomeric infusion pump after colon cancer resection. Blood samples were collected throughout the infusion and up to 12 hours after infusion and were analyzed by high-performance liquid chromatography (HPLC) for total and unbound ropivacaine concentrations in plasma. Alpha1 acid glycoprotein (AAG) concentrations were measured at 0 and 48 hours to assess possible changes in ropivacaine protein binding after surgery. Postoperative pain control was assessed using 12 hour visual analog scale (VAS) scores. Patient-controlled analgesia (PCA) using fentanyl was freely available in parallel for breakthrough pain, with usage and consumption compared with a historical cohort. The mean +/- SD Cmax total plasma ropivacaine concentration (n = 5) from 12 hours to the end of the infusion was 4.5 +/- 2.6 mg/L, comparable with the previously published threshold for CNS toxicity in the most sensitive patient studied (3.4 mg/L). However, the corresponding maximum unbound ropivacaine concentration (ie, the pharmacologically active moiety) of 0.07 +/- 0.01 mg/L ranged from four- to sevenfold below the reported toxicity threshold (0.34 mg/L). The apparently greater safety margin seen with unbound ropivacaine may have resulted from a significant increase (mean 63%, P < 0.05) in AAG concentrations measured at 48 hours after surgery. This reduction resulted from the known AAG reaction after surgical intervention, resulting in a reducing unbound ropivacaine fraction throughout the 96 hour infusion in all patients. Mean subjective 12 hour pain scale scores at rest and on movement showed large variability between patients. No signs or symptoms of ropivacaine toxicity were observed or reported on questioning. In this limited sample, extending the infusion period from the presently approved 48 hours to 96 hours seems to be a safe alternative and/or adjunct to standard opiate analgesia after colorectal surgery using a right lateral transverse incision, hence reducing the incidence of opiate adverse effects and enhancing recovery. Unbound ropivacaine concentrations suggest there is scope for testing elevated doses to enhance efficacy further.

Infiltration continue prépéritonéale d'anesthésiques locaux pour l'analgésie après laparotomie. Données préliminaires

INTRODUCTION

Continuous administration of local anesthetic through a catheter placed in the scar of a laparotomy is a postoperative analgesic technique, which seems effective but remains little developed and poorly codified.

METHODS

In this prospective evaluation, we present a series of 25 observations of adult patients scheduled for abdominal laparotomy, to which a multiperforate catheter was placed at the end of the intervention by the surgeon in pre-peritoneal position, allowing the continuous perfusion of ropivacaïne over the first 48 postoperative hours. Patients received intravenous paracetamol associated with ketoprophene or nefopam. Opiates were given as rescue analgesics, in case of failure in pain relief, defined on objective criteria measured on visual analogic scale (VAS).

RESULTS

The feasibility of the technique was excellent, except in one case of catheter obstruction. Pain was adequately relieved, with a majority of patients having VAS scores lower than 3/10 cm with the VAS, as well as rest as during mobilization. Only 9 patients needed morphine rescue analgesics. There was no sign of clinical overdose nor parietal complication related to the technique. Blood dosages of ropivacaine, carried out among 5 patients having received 600 mg daily, showed serum concentrations below the thresholds of toxicity.

CONCLUSIONS

These results reveal a good effectiveness of the method, with moderate pain intensity and a low analgesic consumption. The local and general tolerance was excellent.

Effect of propofol on ropivacaine metabolism in human liver microsomes

A combination of the general anesthetic propofol and epidural anesthesia with a local anesthetic is widely used. The metabolism of ropivacaine and that of lidocaine are mediated by similar P450 isoforms. Previously, propofol was found to inhibit the metabolism of lidocaine in vitro. Here we investigated whether propofol inhibits the metabolism of ropivacaine using human liver microsomes in vitro. Ropivacaine (6.0 micromol.l(-1)) as the substrate and propofol (1-100 micromol.l(-1)) were reacted together using human microsomes. The concentrations of ropivacaine and its major metabolite 2',6'-pipecoloxylidide (PPX) were measured using high-performance liquid chromatography. The metabolic activity of ropivacaine was reflected in the production of PPX. The inhibitory effects of propofol on ropivacaine metabolism were observed to be dose-dependent. The IC50 of propofol was 34.9 micromol.l(-1). Propofol shows a competitive inhibitory effect on the metabolism of ropivacaine (i.e., PPX production mediated by CYP3A4) in human CYP systems in vitro.

The Pharmacokinetics and Efficacy of Ropivacaine Continuous Wound Instillation After Spine Fusion Surgery

Because local anesthetic continuous wound instillation has not been evaluated after spine fusion surgery, we designed this study to determine whether this technique could enhance analgesia and improve patient outcome after posterior lumbar arthrodesis. Thirty-eight patients undergoing spine stabilization were randomly divided into two groups. The M group received a postoperative baseline IV infusion of morphine plus ketorolac for 24 h, and the R group received IV saline. In both groups, a multihole 16-gauge catheter was placed subcutaneously; in the R group, the wound was infiltrated with a solution of ropivacaine 0.5% 200 mg/40 mL, and infusion of ropivacaine 0.2% 5 mL/h was maintained for 55 h. In the M group, saline infusion was given at the same rate. Pain scores were taken at rest and on passive mobilization by nurses blinded to patient analgesic treatment. The total plasma ropivacaine concentration was evaluated. Pain scores and rescue medication requirements (diclofenac and tramadol) were significantly less in the R group than in the M group. Postoperative blood loss was less and the length of hospital stay was shorter in the R group. The ropivacaine peak total plasma concentration occurred at 24 h during infusion and was within safe limits; no toxic local anesthetic side effects were observed. These results suggest that wound infiltration and continuous instillation of ropivacaine 0.2% is effective for pain management after spine stabilization surgery.

IMPLICATIONS

Postoperative pain after lumbar arthrodesis is related to soft tissue and muscle dissection and to manipulations and removal at the operation site. By blocking noxious stimuli from the surgical area, infiltration and wound perfusion with ropivacaine were more effective in controlling pain than systemic analgesia.

Pharmacokinetics and efficacy of ropivacaine continuous wound instillation after joint replacement surgery † †Declaration of interest. This work was supported by AstraZeneca, Basiglio, Milano, Italy. Presented in part at the Third European Congress of Orthopaedic Anaesthesia, 31 May–2 June 2001, London, UK

BACKGROUND

As continuous wound instillation with local anaesthetic has not been evaluated after hip/knee arthroplasties, our study was designed to determine whether this technique could enhance analgesia and improve patient outcome after joint replacement surgery.

METHODS

Thirty-seven patients undergoing elective hip/knee arthroplasties under spinal block were randomly assigned to two analgesia groups. Group M received continuous i.v. infusion of morphine plus ketorolac for 24 h. Then, a multi-hole 16 G catheter was placed subcutaneously and infusion of saline was maintained for 55 h. Group R received i.v. saline. Thereafter the wound was infiltrated with a solution of ropivacaine 0.5% 40 ml, then a multi-hole 16 G catheter was placed subcutaneously and an infusion of ropivacaine 0.2% 5 ml h(-1) was maintained for 55 h. Visual analogue scale scores were assessed at rest and on passive mobilization by nurses blinded to analgesic treatment. Total plasma ropivacaine concentration was measured.

RESULTS

Group R showed a significant reduction in postoperative pain at rest and on mobilization, while rescue medication requirements were greater in Group M. Total ropivacaine plasma concentration remained below toxic concentrations and no adverse effects occurred. Length of hospital stay was shorter in Group R.

CONCLUSION

Infiltration and wound instillation with ropivacaine 0.2% is more effective in controlling postoperative pain than systemic analgesia after major joint replacement surgery.

[Use of ropivacaine for peridural postoperative analgesia]

OBJECTIVES

To describe pharmacology and toxicology of ropivacaine. To assess the clinical efficacy of ropivacaine when used for postoperative epidural analgesia and to provide recommendations for clinical practice.

DATA SOURCES

Search in the Medline data base of original articles in French and English published since 1995, using the following key words: ropivacaine, postoperative analgesia, epidural, caudal block.

STUDY SELECTION

Prospective randomised studies in adults and children were selected. Letters to editors and editorials were excluded.

DATA EXTRACTION

Articles have been analyzed: to determine the dose of ropivacaine required for postoperative epidural analgesia, to assess the benefits of combination of epidural ropivacaine and additives (opioids or other), to compare epidural ropivacaine and bupivacaine and to assess the use of ropivacaine via caudal route for paediatric postoperative analgesia.

DATA SYNTHESIS

20 mg h-1 of ropivacaine is required to provide effective analgesia. This dose produces a motor block in a significant number of patients. Combination with an opioid allows for a reduction in ropivacaine requirement and subsequently in the incidence of motor blockade. In adults, equipotency ratio of ropivacaine and bupivacaine varies between 1.5/1 and 1/1 depending upon the concentration used. At equipotent doses, early postoperative mobilisation is facilitated with ropivacaine. In case of paediatric caudal analgesia, this ratio is close to 1.

CONCLUSIONS

Epidural ropivacaine combined with opioid provide good postoperative pain relief. Reduction in the incidence of motor blockade and safe toxicological profile make this local anaesthetic a suitable alternative of bupivacaine for postoperative epidural analgesia.

Update on ropivacaine

Long-acting local anaesthetics are primarily used in the practice of anaesthesia, particularly in regional anaesthesia and analgesia. Ropivacaine is a new long-acting local anaesthetic that has been the focus of interest because of its increased cardiovascular safety compared with bupivacaine. Other advantages of ropivacaine over bupivacaine include a greater sensorimotor differential block and shorter elimination half-life (t(1/2)), with a lower potential for accumulation. The most important attribute of ropivacaine, however, is its increased margin of safety compared with bupivacaine when given in equal doses. Many post-marketing studies have focused on the comparisons of efficacy in blocks and toxicity profiles of bupivacaine versus ropivacaine. Recent animal toxicity studies confirm the results of original studies showing that ropivacaine has less cardiovascular toxicity than bupivacaine with respect to direct myocardial depression, success of resuscitation and arrhythmogenic potential when given in equal doses. Reduced cardiotoxicity may be a distinct characteristic of ropivacaine. A review of current literature suggests that, at clinically relevant doses, ropivacaine provides the lowest potential risk of cardiotoxicity for inadvertent intravascular injection. Studies are currently under way comparing ropivacaine with levobupivacaine, the latest addition to the group of long-acting local anaesthetics.