Unbound Ropivacaine Research Articles

Safety of blood reinfusion after local infiltration analgesia with ropivacaine in total knee arthroplasty

The authors hypothesized that it is safe to combine local infiltration analgesia (LIA) in total knee arthroplasty (TKA) with a retransfusion drain since ropivacaine concentrations would not exceed the arterial toxicity threshold concentrations of 4.3 mg/L for total and 0.56 mg/L for unbound ropivacaine. 22 patients scheduled for primary TKA were included. During surgery three peri-articular injections with ropivacaine (300 mg) were given. Plasma and shed blood samples were taken at 0, 1, 3, 6, 7, and 24 hours postoperatively. At 6 hours postoperatively, the total ropivacaine plasma concentration ranged from 0.26 to 1.53 mg/L and unbound ropivacaine from 0.03 to 0.12 mg/L. At 7 hours, the total ropivacaine plasma concentration ranged from 0.19 to 1.71 mg/L and unbound ropivacaine from 0.02 to 0.09 mg/L. In the collected shed blood, a total of 0.27 to 12.8 mg (median 3.73 mg) unbound ropivacaine was present. Reinfusion would lead to an addition of 3.73 mg (median) unbound ropivacaine that would be reinfused into the patient. The calculated (modeled) estimation regarding the maximum unbound ropivacaine plasma concentration showed a median value of 0.114 mg/L (IQR: 0.09, 0.12 mg/L). All concentrations were well below reported toxicity thresholds. The combination of LIA and reinfusion presented herein are considered safe. However, differences in pain protocol lead to changes in the safety evaluation. Compared with previous studies, the technique of administration is of greater importance for the effect on unbound ropivacaine because of unknown mechanisms.

Ropivacaine 0.4% iontophoresis versus continuous catheter infusion after iliac crest bone grafting in lumbar spine surgery

BackgroundIliac crest (IC) pain accompanies IC grafting in spine surgery. The study evaluates the effectiveness of ropivacaine 0.4% iliac crest iontophoresis as compared to infusion through an IC catheter.MethodsThirty patients, 10 in each group, undergoing lumbar spine surgery had an intraoperative epidural block performed and initiated with 20 ml ropivacaine, 0.5% (100 mg) at termination of surgery and after 6 h maintained for 48 h (t48) at 10 ml/h with ropivacaine, 0.2%. Thirty millilitres NaCl, 0.9% (Group I “placebo group” and Group II “ropivacaine iontophoresis group”) or 30 ml ropivacaine, 0.4% (Group III “ropivacaine IC catheter group”) was also administered via an intraoperatively placed IC catheter. At t0, and for 48 h, 5 ml/h ropivacaine, 0.4% was administered via the IC catheter in Group III. In Group II, 30 ml ropivacaine, 0.4% iontophoresis was done using iontocare iontophoresis device. At t0 and for 48 h, 5 ml 0.4% ropivacaine iontophoresis was done at iliac crest site every hour using the iontocare device in Group II. Any further pain was controlled using intravenous morphine 0.1% in 5 mg increments. Pain assessment scores at IC site and at surgical site were evaluated at rest and at motion every 8 h for 48 h and after 4 m. Unbound and total plasma ropivacaine, morphine consumption, and patient satisfaction were evaluated.ResultsAt IC site, significant lower pain scores were elucidated in Groups II and III as compared to Group I at rest and at motion in the initial 48 h and at motion after 4 m. Plasma unbound ropivacaine was higher significantly in Group III at t48 when compared with Group I. Morphine consumption was lower significantly in Groups II and III at 24 and at 48 h when compared with Group I.ConclusionsRopivacaine IC iontophoresis provides safe effective analgesia for the initial 48 h and after 4 m.

Continuous Elastomeric Pump-Based Ropivacaine Wound Instillation after Open Abdominal Aortic Surgery: How Reliable Is the Technique?

We aimed at quantifying the impact of continuous wound infusion with ropivacaine 0.33% on morphine administration and subjective pain relief in patients after open abdominal aortic repair in a double-blind, placebo-controlled study. Before closing the abdominal wound, 2 multihole ON-Q® Soaker Catheters™ (I-Flow Corporation, Lake Forest, California, USA) were placed pre-peritoneally in opposite directions. Either ropivacaine 0.33% or saline 0.9% was delivered by an elastomeric pump at a rate of 2 mL/h for 72 hours in each of the catheters. Postoperative pain and morphine administration were assessed using the numerical rating scale (NRS) in 4-hour intervals. Total plasma concentrations of ropivacaine, unbound ropivacaine, and α1-acid glycoprotein (AAG) were measured daily. Mean arterial pressure, pulse rate, oxygen saturation, total amount of morphine administration, ventilation time, and length of stay in the intensive care unit (ICU) were recorded. At the end of the study period, the wound site and the condition of the catheters were assessed. The study was terminated prematurely due to a malfunction of the elastomeric balloon pump resulting in toxic serum levels of total ropivacaine in 2 patients (11.4 μmol/L and 10.0 μmol/L, respectively) on the second postoperative day. Six patients had been allocated to the ropivacaine group, and 9 patients had been allocated to the control group. Demographic and surgical data were similar in both groups. During the first 3 postoperative days, no difference between the ropivacaine and the control group was found in NRS (P = .15, P = .46, and P = .88, respectively) and morphine administration (P = .48). Concentrations of unbound serum ropivacaine (0.11 ± 0.08 μmol/L) were below toxic level in all patients. Continuous wound infusion of ropivacaine 0.33% 2 mL/h using an elastomeric system was not reliable and did not improve postoperative pain control in patients after open abdominal aortic surgery.

Continuous Infusion of Ropivacaine for Pain Relief after Iliac Crest Bone Grafting for Shoulder Surgery

The aim of the study was to compare the efficacy of either ropivacaine or placebo through an iliac crest (IC) catheter after Bankart repair with IC bone grafting. With approval of the local ethics committee and after written informed consent was obtained, 36 patients had an interscalene catheter placed preoperatively. Intraoperatively, the surgeon placed a catheter at the IC donor site. At the end of surgery, 30 ml ropivacaine, 0.5% (ropivacaine group), or 30 ml NaCl, 0.9% (placebo group), was administered. Ropivacaine, 0.2%, was started 6 h after the initial block through the interscalene catheter for 48 h (t48) in all patients. At t0, the patient received either 5 ml/h ropivacaine, 0.2% (ropivacaine group), or 5 ml/h NaCl, 0.9% (placebo group), for 48 h through the IC catheter. All patients received an intravenous morphine patient-controlled analgesia device. Pain scores at the shoulder and at the IC donor site were assessed at rest and during motion every 8 h for 48 h and after 3 months. Plasma concentrations of total and unbound ropivacaine, morphine consumption, and patient satisfaction were assessed. At the IC donor site, pain was significantly lower in the ropivacaine group compared with the placebo group at rest and during motion at any time. Total and unbound plasma concentrations of ropivacaine were below the toxic threshold in both groups. Morphine consumption was significantly lower in the ropivacaine group after 24 and 48 h. Patient satisfaction was significantly higher in the ropivacaine group. At 3 months, pain at the IC during motion was significantly lower in the ropivacaine group. Continuous application of 0.2% ropivacaine through an IC catheter after Bankart repair with IC bone grafting is an effective method for pain relief for the first 48 h, with few adverse effects and high patient satisfaction. The benefit of this technique is still present after 3 months.

Pharmacokinetics and Efficacy of Long-Term Epidural Ropivacaine Infusion for Postoperative Analgesia

The aim of this study was to evaluate the pharmacokinetics and efficacy of the new local anesthetic ropivacaine when used for epidural infusion for up to 72 h after major orthopedic surgery. Immediately after surgery, an epidural infusion of ropivacaine 2 mg/mL was begun at a rate of 6 mL/h in 11 patients. The infusion rate was then adjusted according to patient analgesic needs or side effects. Blood samples were taken during and after the infusion to determine total and unbound ropivacaine and alpha1-acid glycoprotein (AAG) concentrations. Patients were assessed regularly for sensory and motor block and pain using a visual analog scale (VAS) score (0-100 mm). Ten patients received 63-72 h of infusion. Total plasma concentrations of ropivacaine and binding protein (AAG) increased during the infusion such that free concentrations plateaued or began to fall over time. VAS values during mobilization were less than 40 mm in 93% of patients. The majority of patients had no measurable motor block once the surgical block had regressed. When epidural ropivacaine was titrated to achieve a stable sensory block, there was a low incidence of motor block, and free plasma ropivacaine levels were well below the toxic range. The pharmacokinetics of continuous epidural infusions of ropivacaine are described in patients for up to 72 h postoperatively. Clinical efficacy and side effects are also reported. An understanding of the plasma concentrations obtained and modes of elimination during prolonged epidural infusion is important for safe, routine clinical use in postoperative analgesia.

Pharmacokinetics and Efficacy of Long-Term Epidural Ropivacaine Infusion for Postoperative Analgesia

The aim of this study was to evaluate the pharmacokinetics and efficacy of the new local anesthetic ropivacaine when used for epidural infusion for up to 72 h after major orthopedic surgery.Immediately after surgery, an epidural infusion of ropivacaine 2 mg/mL was begun at a rate of 6 mL/h in 11 patients. The infusion rate was then adjusted according to patient analgesic needs or side effects. Blood samples were taken during and after the infusion to determine total and unbound ropivacaine and alpha1-acid glycoprotein (AAG) concentrations. Patients were assessed regularly for sensory and motor block and pain using a visual analog scale (VAS) score (0-100 mm). Ten patients received 63-72 h of infusion. Total plasma concentrations of ropivacaine and binding protein (AAG) increased during the infusion such that free concentrations plateaued or began to fall over time. VAS values during mobilization were less than 40 mm in 93% of patients. The majority of patients had no measurable motor block once the surgical block had regressed. When epidural ropivacaine was titrated to achieve a stable sensory block, there was a low incidence of motor block, and free plasma ropivacaine levels were well below the toxic range. Implications: The pharmacokinetics of continuous epidural infusions of ropivacaine are described in patients for up to 72 h postoperatively. Clinical efficacy and side effects are also reported. An understanding of the plasma concentrations obtained and modes of elimination during prolonged epidural infusion is important for safe, routine clinical use in postoperative analgesia. (Anesth Analg 1997;85:1322-30)