Anesth Analg 2004;99:45-48
© 2004 International Anesthesia Research Society
doi: 10.1213/01.ANE.0000120162.42025.D0
PEDIATRIC ANESTHESIA
William J. Greeley Section Editor
A Comparison of Epidural Bupivacaine, Levobupivacaine, and Ropivacaine on Postoperative Analgesia and Motor Blockade
Pasquale De Negri, MD*,
Giorgio Ivani, MD
,
Tiziana Tirri, MD*,
Pasqualina Modano, MD*,
Cesare Reato, MD*,
Staffan Eksborg, PhD
, and
Per-Arne Lonnqvist, MD PhD
*Department of Anesthesia, ICU and Pain Management, Centro di Riferimento Oncologico della Basilicata-Cancer Center, Rionero in Vulture, Potenza, Italy;
Department of Pediatric Anesthesia and Intensive Care Unit, "Regina Margherita" Children’s Hospital, Turin, Italy; and
Department of Women and Child Health and Department of Surgical Sciences, Karolinska Institute, Stockholm, Sweden
Address correspondence to Pasquale De Negri, MD, Department of Anesthesia, ICU and Pain Management, CROB-Cancer Center, Strada Provinciale del Vulture 8, Rionero in Vulture (PZ), 85028, Italy. Address e-mail to pdenegri{at}crob.it Reprints will not be available from the authors.
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Abstract
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In this prospective, randomized, observer-blinded clinical trial, we compared the incidence of unwanted lower extremity motor blockade and the analgesic efficacy between small-dose (0.125%; 0.2 mg · kg–1 · h–1) postoperative epidural infusions of bupivacaine (Group B; n = 28), levobupivacaine (Group L; n = 27), and ropivacaine (Group R; n = 26) in children after hypospadias repair. Motor blockade and pain were assessed at predetermined time points during 48 h by using a modified Bromage scale and the Children’s and Infant’s Postoperative Pain Scale (CHIPPS). Postoperative analgesia was almost identical in all three study groups (CHIPPS range, 0–3), with no need for the administration of supplemental analgesia in any patient. However, significantly more patients in Group B (n = 6; P = 0.03) displayed signs of unwanted motor blockade during the observation period compared with Group L (n = 0) and Group R (n = 0). In conclusion, significantly less unwanted motor blockade was associated with postoperative epidural infusions of 0.125% levobupivacaine or ropivacaine in children after hypospadias repair as compared with a similar infusion of bupivacaine. However, no difference with regard to postoperative analgesia could be detected among the three different local anesthetics studied.
IMPLICATIONS: The use of the newer local anesthetics levobupivacaine and ropivacaine was associated with similar postoperative analgesia but less unwanted muscle weakness of the lower extremities compared with the previous standard (bupivacaine) when administered as small-concentration (0.125%; 0.2 mg · kg–1 · h–1) postoperative epidural infusions in children.
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Introduction
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Bupivacaine has, until recently, been the drug of choice for postoperative epidural infusions in children. Despite a reasonable safety profile, bupivacaine is currently being replaced by many anesthesiologists with new local anesthetics: levobupivacaine and ropivacaine. These local anesthetics are associated with less risk for cardiac and central nervous system toxicity and are also less likely to result in unwanted postoperative motor blockade (1,2). Despite numerous publications with regard to the use of levobupivacaine and ropivacaine in children, no randomized studies have compared the use of these three drugs for continuous postoperative epidural infusion. Thus, the aim of this investigation was to compare the effect of a continuous postoperative epidural infusion of these three local anesthetic drugs on motor blockade and pain relief after hypospadias repair.
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Methods
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After IRB approval and written, informed parental consent, 90 boys (2–6 yr of age; ASA status I) scheduled for hypospadias repair were included in this prospective, randomized study. All patients received oral premedication with midazolam 0.5 mg/kg approximately 45 min before arrival in the operating room. After standard noninvasive monitoring was applied, general anesthesia was induced with sevoflurane 8% by face mask. After the induction of anesthesia, the airway was managed either by a laryngeal mask airway or by endotracheal intubation (facilitated by atracurium 0.5 mg/kg). Anesthesia was thereafter maintained with isoflurane 0.8%–1% in an oxygen/air mixture throughout the remaining part of the procedure.
With the patient in the lateral decubitus position, an epidural catheter (Portex 19-gauge epidural kit) was placed at the L5-S1 level by using a loss-of-resistance technique. The catheter was threaded approximately 3 cm in the caudal direction. After placement of the epidural catheter, all patients received incremental injections of 0.2% ropivacaine up to a total dose of 1.4 mg/kg while they were watched for signs of toxicity (no epinephrine-containing test dose was used). The maximum volume of ropivacaine was 20 mL. The patient was then prepared, and surgery was allowed to commence. The block was judged as successful if there was no or a only minor (<15% increase) hemodynamic reaction (heart rate, noninvasive arterial blood pressure, or both) to the start of surgery. Sixty minutes after the initial epidural injection, a continuous infusion of plain ropivacaine 0.125% was started at a rate of 0.2 mg · kg–1 · h–1 and was continued for the duration of the surgical procedure.
After emergence from the anesthetic, patients were transferred to the recovery area. Immediately after arrival to the recovery room, patients received, according to the previous randomization, 1 of 3 different epidural infusions—levobupivacaine 0.125% 0.2 mg · kg–1 · h–1 (group L), ropivacaine 0.125% 0.2 mg · kg–1 · h–1 (group R), or bupivacaine 0.125% 0.2 mg · kg–1 · h–1 (group B)—for 48 h. The infusions were prepared, given a code number, and connected to the patient by an operator who took no further part in the study.
Postoperative analgesia (Fig. 1) and the degree of motor blockade were assessed every 4 h throughout the first 48 postoperative hours. Analgesia was assessed by using the Children’s and Infant’s Postoperative Pain Scale (CHIPPS) (3), and the degree of motor blockade was recorded by using a modified Bromage scale (4). Trained nurses unaware of the randomization performed all the postoperative assessments.
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Figure 1. Mean CHIPPS scores for the first 48 postoperative hours. A CHIPPS score exceeding 3 indicated a need for supplemental rescue analgesia. Levo = levobupivacaine; bupi = bupivacaine; ropi = ropivacaine.
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Patients were not prescribed any postoperative analgesics apart from the epidural infusion. Rescue analgesia with acetaminophen-codeine suppositories (200 mg/5 mg) was administered according to patient weight if the CHIPPS score was >4. The time to first need for rescue analgesia and the total amount of supplemental analgesics were also recorded during the 48-h observation period.
Statistical analysis was performed by nonparametric tests as appropriate, and P values <0.05 were considered significant. On the basis of pilot data, the study was designed to be able to detect a 15% difference between study groups with regard to the number of patients with an absence (score 0) or presence (score 1–3) of motor blockade during the postoperative period. A power calculation based on these assumptions together with an 
of 0.05 and a ß of 0.8 resulted in the need for 
25 patients in each treatment group.
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Results
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A total of 90 patients were included in the study. Two patients in group B, three patients in group L, and four patients in group R were excluded from the analysis because of an inadequate block or modification of the planned surgery after inclusion in the study. Thus, the final number of patients in each group was 28, 27, and 26 for groups B, L, and R, respectively. Patient demographics and other basic data are displayed in Table 1.
None of the patients displayed any signs of motor blockade during the first 12 h of infusion. Only patients in group B displayed signs of motor blockade during the 12- to 48-h postoperative period. Thus, 6 patients in group B had motor block scores of 1 or 2 during the postoperative period, a finding that was significantly higher compared with both group L (P < 0.03) and group R (P < 0.03). None of the patients had a motor block score of 3. If expressed as 95% confidence intervals for the occurrence of unwanted postoperative motor block (percentage of patients) these 95% confidence intervals were 0%–10%, 0%–11%, and 8%–41% for groups L, R, and B, respectively.
No significant difference among groups could be observed at any of the observation points during the 0- to 48-h postoperative period with regard to CHIPPS score (Fig. 1). Because none of the patients had a CHIPPS score of >4, no supplemental analgesia was administered in any of the study groups. No other side effects were noted in any patient during the study period.
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Discussion
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The main finding of this study was that epidural infusions of 0.125% solutions of bupivacaine, levobupivacaine, or ropivacaine resulted in almost identical postoperative analgesia after hypospadias repair in children. No signs of postoperative motor blockade were observed in patients given levobupivacaine or ropivacaine, whereas bupivacaine caused minor to moderate postoperative motor block in approximately 20% of the patients.
The primary aim of this study was to evaluate whether postoperative epidural infusions of the studied local anesthetics were associated with the occurrence of unwanted motor blockade. To allow this, we had to avoid a situation in which the intraoperative activation of the epidural blockade by a bolus injection of local anesthetics would confound the baseline situation after surgery. A different design might have caused a situation in which some patients had unwanted motor blockade immediately after surgery. Because caudal bolus injection of 0.2% ropivacaine in children has not been associated with motor blockade (4–6), and because ropivacaine (based on minimal local anesthetic concentrations [MLAC] studies) is regarded as less potent than bupivacaine (7,8), we decided to activate the epidural blockade during surgery with 0.2% ropivacaine in all patients. The observation that all patients had a motor block score of 0 in the recovery room verifies that this study design achieved the objective of producing a baseline situation with no signs of unwanted motor blockade in any patient.
Our finding of a significantly more frequent incidence of motor blockade with the use of 0.125% bupivacaine infusion versus similar concentrations of levobupivacaine or ropivacaine is in keeping with previous reports of a better discrepancy between analgesia and motor blockade for the new long-acting local anesthetics in adults (1,2). The present finding is also similar to our previously reported data after single-injection caudal blockade in children, where the use of 0.25% bupivacaine caused a more frequent incidence of motor blockade compared with 0.25% levobupivacaine or 0.2% ropivacaine (4). This difference between bupivacaine on one hand and levobupivacaine and ropivacaine on the other was still present in the current study despite the use of more dilute local anesthetic solutions for continuous epidural infusion.
The incidence of unwanted motor blockade associated with the use of bupivacaine could most likely be eliminated if even smaller concentrations were used, but a previous study by Wolf et al. (9) showed that such dilute bupivacaine solutions are associated with an unreliable analgesic effect. Thus, either of the two new long-acting local anesthetics should be used for postoperative epidural infusion instead of bupivacaine to minimize the risk for unwanted postoperative motor blockade in children.
In keeping with previous pediatric studies (4–6,10–12), we were unable to identify any difference with regard to postoperative analgesia among the three different local anesthetics used, despite using only 0.125% concentrations of each drug. This observation was true concerning both CHIPPS scores and the need for supplemental postoperative analgesia. Thus, from a clinical perspective, the 0.125% concentration of the 3 studied local anesthetics appears equipotent with regard to postoperative analgesia after epidural infusion in children.
As noted above, ropivacaine has been claimed to possess only 60% of the analgesic potency of bupivacaine on the basis of findings generated in MLAC studies (7,8). However, the generalization of potency data from MLAC studies has been questioned because of the specific circumstances associated with obstetric epidural analgesia and because of the scientific design of MLAC studies.
In summary, significantly less unwanted motor blockade was associated with postoperative epidural infusions of 0.125% levobupivacaine or ropivacaine in children after hypospadias repair as compared with a similar infusion of bupivacaine. No difference with regard to postoperative analgesia could be detected among the three different local anesthetics studied.
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Accepted for publication January 16, 2004.
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Abstract
Introduction
