Anesth Analg 2008; 106:1559-1561
© 2008 International Anesthesia Research Society
doi: 10.1213/ane.0b013e318168b493
BRIEF REPORT
Postoperative Analgesic Efficacy of Peripheral Levobupivacaine and Ropivacaine: A Prospective, Randomized Double-Blind Trial in Patients After Total Knee Arthroplasty
Florian Heid, MD*,
Nicole Müller*,
Tim Piepho, MD*,
Maren Bäres, MD*,
Markus Giesa, MD ,
Philipp Drees, MD,
Andreas Rümelin, MD, PhD*, and
Christian Werner, MD, PhD*
From the Departments of *Anesthesiology, and Orthopaedic Surgery, Johannes Gutenberg-University Mainz, Germany.
Address correspondence and reprint requests to Florian Heid, MD, Department of Anesthesiology, Johannes Gutenberg-University Mainz, Langenbeckstr. 1 D-55131 Mainz, Germany. Address e-mail to heid{at}uni-mainz.de.
Abstract
BACKGROUND: Several previous trials have characterized the intra- and postoperative effects of the recently introduced local anesthetics, levobupivacaine and ropivacaine, for a variety of continuous peripheral nerve blocks.
METHODS: We compared the analgesic efficacy of levobupivacaine 0.125% versus ropivacaine 0.2% via patient-controlled femoral nerve analgesia after total knee arthroplasty. In a double-blind, randomized, prospective design, 60 patients received femoral infusion with either substance. We analyzed postoperative local anesthetic consumption, pain scores, motor block, and opioid requirements over 72 h.
RESULTS: Pain scores, motor block incidence, and opioid requirements were low and not different between the groups. Ropivacaine consumption in milligrams was 67% higher than that of levobupivacaine.
CONCLUSIONS: Both levobupivacaine 0.125% and ropivacaine 0.2% provide similar analgesia after total knee arthroplasty with the latter being less potent.
Several previous trials have characterized the intra- and postoperative effects of the recently introduced local anesthetics, levobupivacaine and ropivacaine, for a variety of continuous peripheral nerve blocks,1–3 although none has compared the potency of these drugs after total knee arthroplasty (TKA), when effective postoperative analgesia may be a prerequisite for successful surgery.4
This prospective, randomized, double-blind study investigated the postoperative analgesic efficacy of levobupivacaine 0.125% and ropivacaine 0.2% during patient-controlled femoral nerve analgesia (PCRA) in patients after TKA.
METHODS
This study was approved by the local ethical care committee and adhered to the Helsinki Declaration. After written, informed consent, 65 patients scheduled for TKA were enrolled. Computer-assisted randomization of the patients was performed to allocate the patients to two study groups consisting of 30 patients each.
Patients received oral premedication with oxazepam (10 mg). After establishing standard monitoring (noninvasive arterial blood pressure, 3-lead electrocardiogram, and oxygen saturation), the femoral nerve was identified by electric nerve stimulation using an insulated needle (Transmed 16G x 83 mm, Transmed Medizintechnik, Bad Wünnenberg, Germany). After femoral nerve identification (Stimuplex HNS 11®; Braun, Melsungen, Germany; stimulation with 0.1 ms,  0.4 mA) via adequate motor response (patella movements), 35 mL of the preoperative local anesthetic (Ropi group: ropivacaine 0.5%; Levo group: levobupivacaine 0.3125%) was injected incrementally in a blinded fashion. Thereafter, a nonstimulating catheter (Transmed 21G x 50 cm, Transmed Medizintechnik) was advanced 3–4 cm beyond the needle tip. Additionally, a sciatic nerve block was performed via a posterior approach.5 Correct position of the needle (Pajunk Nanoline 22 g x 80 mm, Pajunk, Geisingen, Germany) was again confirmed by electric nerve stimulation. Foot flexion at 0.1 ms and 0.4 mA was regarded as adequate motor response and 25 mL of the preoperative local anesthetic (ropivacaine 0.5% or levobupivacaine 0.3125%) was injected in a blinded fashion. Upon completion of the regional procedures, general anesthesia was induced using IV propofol (2 mg/kg) and sufentanil (10 µg). If indicated, a laryngeal mask airway was inserted. In patients with morbid obesity (body mass index >30) or reflux disease, atracurium (0.5 mg/kg) was administered for orotracheal intubation. Anesthesia was maintained using sevoflurane (1.0–1.5 end-tidal vol%) in an air/O2-mixture (Fio2 >0.3, flow 0.5 L/min). If required, supplemental IV sufentanil and/or neuromuscular blockade were administered. Approximately 30–45 min before emergence from anesthesia, IV paracetamol (1 g) was infused.
Postoperatively, the Ropi group received ropivacaine 0.2% for PCRA and levobupivacaine 0.125% was administered to the Levo group. Upon postanesthesia care unit arrival, we connected the PCRA pump (Graseby 9300 PCA, SIMS Deltec Inc., St. Paul, USA), which supplied the test local anesthetic postoperatively during the 72-h study period (blinded, background infusion: 5 mL/h; bolus dose 5 mL; lockout period: 30 min). The primary end-point of the study was defined as postoperative local anesthetic consumption. Secondary end-points were pain intensity, presence of motor block, and the need for supplemental opioid analgesia. Data acquisition was performed upon postanesthesia care unit release (T0) and 24 (T1), 48 (T2), and 72 (T3) h postoperatively. In the presence of inadequate analgesia (rest pain  40 according to a numeric rating scale (NRS) score between 0 and 100), the opioid piritramid (15 mg) was injected subcutaneously as a rescue medication. In case of persistent inadequate analgesia, femoral nerve analgesia was discontinued and converted to systemic opioid analgesia using piritramid (IV patient-controlled analgesia; bolus dose: 1.5 mg; lockout period: 10 min). To evaluate motor impairment, the physiotherapists caring for patients were asked if ambulation was satisfactory.
The following data were recorded:
- Postoperative cumulative total volume of local anesthetic in milliliter;
- Postoperative cumulative total dose of local anesthetic in milligram;
- Rest pain and dynamic pain (leg movement) determined by a NRS (0–100; 0 = no pain; 100 = maximum imaginable pain);
- The additional need and dosage for/of opioids;
- Motor block (according to the physiotherapists’ feedback); and
- Patient satisfaction with the pain management determined by NRS.
A detailed description of biometrical methods was described earlier by the authors.6
RESULTS
In five patients, the primary outcome variable could not be obtained (catheter dislocation in one Levo patient, catheter ineffective in one of each group and preterm termination due to patient's wish in one of each group). They were regarded as dropouts and replaced by additionally randomized individuals.
There were no significant differences in patient characteristics between the groups (Table 1). The cumulative volume in milliliter of the infused local anesthetic and the number of bolus doses supplied by the PCRA pump were similar for both groups (P = 0.98; Table 2). The cumulative total consumption of ropivacaine in milligram substance was 1.6-fold higher than that of levobupivacaine (P < 0.000; Table 2). Opioid requirements did not differ between groups (P = 0.098, Table 2). In one patient of the Levo group, ambulation was not possible due to motor block. There were no significant differences regarding the course of pain intensity (Table 3). Patient satisfaction with pain management was high and not different between groups (median/sd: ropivacaine: 95/17.56, levobupivacaine: 100/9.59).
DISCUSSION
The present study demonstrated that both levobupivacaine 0.125% and ropivacaine 0.2% provide effective postoperative analgesia in patients after TKA via PCRA. No differences with regard to local anesthetic consumption, additional bolus doses, pain scores, opioid requirements, or motor block incidence were observed. However, the median total dose of ropivacaine (930 mg) was approximately 1.6-fold higher than that of levobupivacaine (556 mg). This corresponds to previous observations when these drugs were applied for continuous interscalene analgesia after open shoulder surgery1,3 or for continuous sciatic nerve block after hallux valgus repair.2 Cursorily viewed, our results simply confirm the previously reported lower potency of ropivacaine. However, as TKA is a surgical intervention, where effective postoperative analgesia may considerably contribute to the surgical result,4 our study adds to the growing body of knowledge concerning the differential potency of levobupivacaine and ropivacaine.
This issue is of increasing importance considering the growing use of peripheral nerve catheters for sustained postoperative analgesia because of the expectation that toxicity should be very infrequent. This makes critical attention to the potency of the drugs selected very important7–9 and underlines the need for further properly designed studies to specifically evaluate the relative anesthetic potency of these drugs.
In summary, the results of this study indicate that for femoral nerve PCRA after TKA levobupivacaine 0.125% and ropivacaine 0.2% provide equal analgesia without substantial benefits for either local anesthetic.
Footnotes
Accepted for publication December 11, 2007.
Supported by an unrestricted educational grant from Abbott GmbH & CO KG, Wiesbaden, Germany.
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