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*Department of Anesthesiology and Intensive Care Unit, Regina Margherita Childrens Hospital, Turin;
Department of Anesthesiology, Intensive Care Unit, and Pain Management, "CROB" Cancer Center, Rionero in Vulture, Italy;
Department of Paediatric Anaesthesia and Intensive Care, Astrid Lindgrens Childrens Hospital, Karolinska Hospital; and
Karolinska Pharmacy and Department of Woman and Child Health, Karolinska Institute, Stockholm, Sweden
Address correspondence and reprint requests to Giorgio Ivani, Chairman, Department of Anesthesiology and Intensive Care, Regina Margherita Childrens Hospital, Piazza Polonia 94, 10126 Turin, Italy. Address e-mail to gioivani{at}libero.it
| Abstract |
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4), and the degree of immediate postoperative motor blockade was determined by use of a 3-point scale. A dose-response relationship was observed both with regard to median duration of postoperative analgesia (0.125%, 60 min; 0.20%, 118 min; 0.25%, 158 min) and the number of patients with evidence of early postoperative motor blockade (0.125%, 0; 0.20%, 4; 0.25%, 8). The 0.125% concentration was associated with significantly less early motor blockade (P = 0.003) but was found to result in a significantly shorter duration of postoperative analgesia (P < 0.05). Based on these results, the use of 0.20% levobupivacaine might represent the best clinical option if a plain levobupivacaine solution is to be used for caudal blockade in children. IMPLICATIONS: The use of 0.125% levobupivacaine for caudal blockade (1 mL/kg) in children (17 yr) was associated with less early postoperative motor blockade but a shorter duration of postoperative analgesia compared with 0.20% and 0.25% solutions.
| Introduction |
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Ropivacaine has been well documented both in adults and children (1,48). However, fundamental information concerning the use of levobupivacaine in children is still lacking despite an adequate bibliography with regard to adult practice (2). Thus, the aim of the current study was to investigate the dose-response relationship of levobupivacaine for caudal blockade in children.
| Methods |
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After the induction of anesthesia, patients were placed in the lateral decubitus position, and a caudal blockade (total volume of local anesthetic 1 mL/kg) was performed. The patients were randomized to receive one of three different concentrations of levobupivacaine by means of a computer-generated random list.
An intraoperative successful blockade was defined as a hemodynamic (HR or NIBP) reaction <20% compared with baseline in response to surgical incision. After emergence from anesthesia, the degree of motor blockade was registered using a simple 3-point scale (0 = no movements, 1 = possible to move the legs, and 2 = able to stand) (9).
Postoperative analgesia was evaluated by the Children and Infants Postoperative Pain Scale (CHIPPS) (10). CHIPPS is a well-validated five-item behavioral scale where each variable (crying, facial expression, posture of the trunk, posture of the legs, and motor restlessness) is given a score of 02 with a total score of
4 identifying the need for supplemental analgesia (10). The CHIPPS score was assessed every 30 min for the first 4 h, hourly for the next 16 h, and thereafter every 2 h when awake until the end of the observation time (24 h). The duration of analgesia, as defined as the time to the first rescue drug administration, was also noted. All postoperative observations were registered by nurses who were blinded to the study. A paracetamol-codeine suppository, based on a paracetamol dose of 40 mg/kg (resulting in approximately 12 mg/kg of codeine because of the fixed drug composition of the suppository), was administered as rescue analgesia if the CHIPPS score was
4.
Data are reported as median (range). The influence of the drug concentration on motor blockade was analyzed by Fishers exact test. Time to first supplemental analgesic request was compared using the Mann-Whitney U-test. A P value <0.05 was considered statistically significant.
| Results |
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Rescue analgesia (caused by a CHIPPS score of
4) was administered to seven patients (35%) in Group 1, eight patients (35%) in Group 2, and six patients in Group 3 (30%) (P = ns). The highest CHIPPS score registered for each individual patient during the first 4 postoperative h is displayed in Table 2. The median times from the end of the surgical procedure to the first administration of supplemental analgesics in these children were 60 min (range, 4575 min), 118 min (range, 60210 min), and 158 min (range, 60660 min) in Group 1, 2, and 3, respectively (Group 1 versus Group 2, P < 0.037; Group 1 versus Group 3, P < 0.053; Group 2 versus Group 3, P < 0.52). The fraction of patients without a need for supplemental analgesia as a function of time is shown in Figure 1. No nausea or vomiting were noted in any of the patients during the observation period.
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| Discussion |
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No differences were observed between the intraoperative efficacies of the various concentrations of levobupivacaine used in the study. However, during the early postoperative phase, an obvious dose-response effect was seen with regard to motor blockade. Only patients receiving 0.125% levobupivacaine were free of postoperative motor blockade, whereas the number of patients with residual motor blockade increased with increasing concentrations of levobupivacaine. In the group treated with 0.25% levobupivacaine, as many as 40% of the patients experienced residual motor blockade during the first postoperative hour. This finding is similar to what has been reported for use of ropivacaine in children. Thus, using ropivacaine concentrations in excess of 0.2% for caudal blockade in children is also associated with an increased incidence of early motor blockade (11,12). The use of ropivacaine 0.2% for caudal blockade rarely causes any effects on early motor function (48), a finding that somewhat contrasts with the 20% incidence of residual motor blockade found in the 0.2% levobupivacaine group. However, the equipotency between ropivacaine and levobupivacaine has been disputed, and the minimum effective local anesthetic concentration studies have found the potency of ropivacaine to be only 60% of racemic bupivacaine (13). Thus, the difference with regard to early postoperative motor function between 0.2% ropivacaine and 0.2% levobupivacaine could only be a reflection of a potency difference between the two drugs.
In patients developing a CHIPPS score of
4 during the postoperative period, a clear relationship between the concentration of levobupivacaine and duration of analgesia was seen. This somewhat contrasts the previous findings by Wolf et al. (14) who were unable to find such a correlation between bupivacaine concentration used and the duration of analgesia. The exclusion of epinephrine as an additive to the local anesthetic in the present study might explain this difference in outcome of the two studies. The use of 0.2% or 0.25% levobupivacaine was associated with a two-fold and 2.6-fold increase in the duration of the block, respectively, compared with the 0.125% solution. However, these results must be interpreted with a certain degree of caution because a similar number of patients in each group had appropriate analgesia (CHIPPS score <4) throughout the 24-hour observation period and thus did not require the administration of supplemental analgesics. In line with the studies by Wolf et al. (14) and Gunter et al. (15), a considerable number of patients in the present study underwent surgical corrections of inguinal hernia or hydrocele. Although this group of patients represents a significant part of the pediatric surgical population, these patients might be suboptimal for the study of postoperative analgesia because a large proportion does not experience pain to the extent that supplemental analgesia is required. Thus, despite the problem with patient recruitment, further studies in this field should perhaps be performed on a patient population with more pronounced problems with postoperative pain relief, e.g., orchidopexy. Furthermore, Verghese et al. (16) have recently shown that efficacy of a caudal block for orchidopexy patients is not only related to the concentrations of the local anesthetic but also to the volume injected. Because the injected volume of local anesthetic was fixed (1 mL/kg), no conclusions in this regard can be drawn for the present study.
Although a moderate degree of residual motor blockade during the first postoperative hour might not be considered a major problem, such an effect can be quite distressing for the child during emergence from anesthesia and could potentially contribute to postoperative agitation and confusion. Therefore, the use of 0.125% levobupivacaine may have a clinical advantage. On the other hand, the use of the 0.125% solution was associated with a quite limited duration of postoperative analgesia in certain patients, and thus, maybe 0.2% levobupivacaine would represent a better clinical compromise between postoperative analgesia and degree of residual motor blockade.
Only limited information has been available regarding the pediatric use of levobupivacaine (9,1720), and no information has been published with regard to the use of different concentrations of levobupivacaine for caudal blockade in children.
The rationale for choosing the concentrations of levobupivacaine used in the present study was based on the following: First, because racemic bupivacaine and levobupivacaine are considered to be equipotent (2), we decided to use the concentrations 0.125% and 0.25%, which previously have been investigated with regard to the optimum concentration of racemic bupivacaine for caudal blockade in children (14,15). Second, there is a relatively large body of data with regard to the use of 0.2% ropivacaine in the setting of pediatric caudal blockade (48). Because of the current discussion relating to the potency of ropivacaine versus levobupivacaine (see below), we decided to include 0.2% levobupivacaine to allow a comparison with previously reported data for ropivacaine.
In conclusion, a dose-response relationship for levobupivacaine was observed both with regard to duration of postoperative analgesia and early postoperative motor blockade. The 0.125% concentration was associated with less early motor blockade but resulted in a shorter duration of postoperative analgesia. Based on the current results, the use of 0.20% levobupivacaine might represent the best clinical option if a plain levobupivacaine solution is to be used for caudal blockade in children.
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