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*Departments of Anesthesia and Critical Care Medicine, and
Departments of Anesthesia and Critical Care Medicine and Biostatistics, Lapeyronie University Hospital, Montpellier, France; and
Nuffield Department of Anesthesia, John Radcliffe University Hospital, Oxford, United Kingdom
Address correspondence and reprint requests to Christophe Dadure, MD, Département dAnesthésie Réanimation A, Hôpital Lapeyronie, 371 Avenue du Doyen G. Giraud, 34295, Montpellier, France. Address e-mail to chdadure{at}yahoo.fr.
| Abstract |
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| Introduction |
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Single-injection popliteal nerve block provides effective pain management after minor foot and ankle surgery in children (16,17) but the duration of pain relief is a maximum of 12 h (16), and this method is thus not suitable for major podiatric surgery. CPNB may provide better postoperative analgesia after major foot surgery in children (3). This prospective randomized study was designed to compare adverse events between CPNB and CEB as well as evaluate the efficacy of both continuous regional analgesia techniques in children undergoing major podiatric surgery.
| Methods |
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Children were randomly assigned to CEB (Group 1) or CPNB (Group 2). Randomization was generated by our institutional Department of Biostatistics. Patients were separated by age, children 1 to 6 years of age (Group A) and children 7 to 12 yr of age (Group B). Group 1A children were those aged from 1 to 6 yr receiving CEB; Group 2A children were those aged from 1 to 6 yr receiving CPNB. Group 1B consisted of children aged from 7 to 12 yr receiving CEB, and group 2B consisted of children aged from 7 to 12 yr receiving CPNB.
The children were premedicated with rectal midazolam (0.4 mg/kg) and atropine (20 µg/kg). General anesthesia was induced in all children using sevoflurane and 1 µg/kg IV fentanyl. Endotracheal intubation and mechanical ventilation were used for the duration of surgery. Anesthesia was maintained with 50% nitrous oxide in oxygen and 1.5%2% sevoflurane.
CPNB (Groups 2A and 2B) was performed before the surgical procedure using a nerve stimulator for precise nerve location (Stimuplex®; B Braun, Melsungen, Germany). Children were placed in the lateral position and a popliteal sciatic nerve block was performed using the landmarks of Singelyn et al. (18) adapted to children. Correct needle placement was identified when an output <0.6 mA elicited a characteristic motor response corresponding to either tibial or common peroneal nerve stimulation. A 20-gauge multiperforated catheter (Plexolong®; Pajunk, Geisingen, Germany) was threaded a distance of 3 to 5 cm and secured with a transparent occlusive dressing.
CEB (Groups 1A and 1B) was performed after induction of general anesthesia, with sterile saline loss-of-resistance technique. Eighteen-gauge, 10-cm Tuohy needles (Perifix®, Braun, Melsungen, Germany) were used for children weighing more than 20 kg, and 19-gauge, 5 cm Tuohy needles (Continuous epidural anesthesia mini kit; Abbott Laboratories, Maidenhead, UK) were used in children weighing between 7 and 20 kg. Each catheter was secured with a transparent occlusive dressing. Before incision, all children received a bolus of 0.5 to 1 mL/kg of an equal volume mixture of 0.25% bupivacaine and 1% lidocaine with 1:200000 epinephrine via the catheter. The bolus was infused over a 5-min period.
In the postoperative period, in awakened and tracheally extubated children, a continuous infusion of 0.2% ropivacaine was administered for 48 h. The continuous infusion rates were 0.1 mL·kg1·h1 for CPNB (24) and 0.2 mL·kg1·h1 for CEB (10,11,19). Niflumic acid 40 mg/kg was administered IV twice daily to all children, with the first dose given at the end of surgery (nonsteroidal antiinflammatory drug usually used as part of multimodal analgesia management). In the postoperative period, sensory blockade was evaluated by testing cold sensation (ether on a ball of cotton wool) at 1 h, 6 h, 12 h, 18 h, 24 h, 36 h, and 48 h. At the same follow-up times, motor blockade was evaluated for selected muscles of each nerve territory using the Bromage scale (20). Also at these times, pain during movement was assessed using either a visual analog scale (VAS) ranging from 0 (no pain) to 10 cm (worst imaginable pain) (Groups 1B and 2B), or the Children and Infants Postoperative Pain Score (CHIPPS) (21) for young children (Groups 1A and 2A). If pain control was considered insufficient (VAS or CHIPPS score >3) during the postoperative study period, an IV injection of 30 mg/kg propacetamol was administered as the initial rescue analgesia. After 30 min, if pain control was still considered insufficient, an IV injection of 0.2 mg/kg nalbuphine was then administered. Amounts of rescue analgesics were noted. At the end of the study period (48 h), parental satisfaction was recorded (unsatisfied, satisfied, very satisfied). Side effects, such as pruritus, nausea, vomiting, dysesthesia, hematoma, urinary retention, local infection, or local anesthetic (LA) toxicity and premature discontinuation of LA infusion, were noted during the study period.
The study protocol called for exclusion of children with unreliable catheter location from analysis of pain score, but any case of unreliable catheter placement was to be included among adverse events of the technique.
Sample size calculation was centered on our primary hypothesis that CPNB decreases adverse events compared with CEB. We chose the incidence of urine retention during the 48-h postoperative period for CEB and CPNB to estimate a probable sample size. We considered a 30% reduction in urine retention incidence to be clinically relevant. Assuming a two-sided type I error protection of 0.05 and a power of 0.80, 25 patients were required in the CEB and CPNB groups to reveal a clinically significant difference. Because the pain score scales were different between 1- to 6-yr-old and 7- to 12-yr-old groups, we also analyzed pain scores by treatment groups and age.
The quantitative anthropometric scores are expressed as median (range); motor blockade as median (range); and pain score as median (25th75th percentiles, 10th90th percentiles, and ranges). Adverse effects are compared in each age group, each treatment group, and in the whole study population. Repeated measure analysis of variance was used for continuous variables. Comparisons between values at the times studied were made using the Mann-Whitney U-test for nonparametric data, and the
2 test was used for categorical data. A significance threshold of P < 0.05 was used. Statistical analysis was performed using SAS software version 8.02 (SAS Institute, Cary, NC).
| Results |
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Complete motor blockade occurred in one patient in each study group (i.e., one in the CEB group and one in the CPNB group) and had resolved in both patients by 6 h.
Adverse events after 48 h were significantly more frequent in the CEB group (Table 3). Urinary retention and premature discontinuation of LA infusion related to technical problems were significantly more frequent in Group 1A (P < 0.05). The reasons for premature discontinuation of infusion were catheter occlusion (n = 1), leakage (n = 2), and catheter dislodgement (n = 3) in the CEB group.
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There was significantly more postoperative nausea or vomiting in Group 1B (P < 0.01). Across all treatment groups, a significantly more frequent incidence of nausea or vomiting and urinary retention occurred in the CEB groups. None of the children had hematoma or associated catheter infection. No dysesthesia or other sign of LA toxicity was noted. No neurological sequelae were noted after withdrawal of the peripheral nerve catheters.
Parental satisfaction was 86% for children in CEB groups and 100% in the CPNB groups. There was no difference between treatment groups.
| Discussion |
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The analysis of pain score values shows effective management of postoperative pain in children with both CEB and CPNB. In all treatment groups, postoperative analgesia was excellent and postoperative pain scores were low and comparable for the two continuous block techniques and both age groups. However, epidural anesthesia for foot and ankle surgery is associated with inadequate analgesia in adults (22,23). The use of CEB for surgery performed in areas innervated by the last two lumbar and first two sacral segments is not recommended in adults (22,23); however, these recommendations were not verified in our pediatric study patients. One explanation is that needle insertion, catheter passage, and injectate distribution are probably facilitated by the relatively larger dimensions of the fat-filled posterior epidural space in early childhood (24). However, in their retrospective evaluation, Jylli et al. (12) found a more frequent incidence of unsatisfactory function of continuous postoperative epidural analgesia in older children. Single-shot popliteal nerve block provides effective pain management after foot and ankle surgery in children (16,17), but the duration of the analgesia is from 8 to 12 hours (16). CPNB has been widely shown to be an effective technique for pain management after foot or ankle surgery in adults (18,2527).
This randomized comparative study demonstrated that CPNB had fewer adverse events compared with CEB in pediatric patients undergoing major foot surgery. Nausea or vomiting has been recognized in 2.3% to 63% of patients undergoing CEB (812,14,19,28). Wood et al. (14) recorded nausea and vomiting in 23% of 190 children using continuous epidural analgesia for postoperative pain management. In a retrospective evaluation, Jylli et al. (12) reported a 2.3% incidence of nausea and vomiting in 482 patients, while Brenn et al. (28) observed a 52% incidence of emesis with CEB in children with cerebral palsy. Pediatric studies using epidural ropivacaine infusions note that nausea and vomiting ranges from 8.3% to 28% (10,11,19). In our study, 40% of children with CEB had nausea or vomiting.
Urinary retention was significantly more frequent in the CEB groups in both age groups. Epidural block with LA produces inhibition of sacral parasympathetic outflow causing detrusor relaxation and enlarged bladder capacity. Lejus et al. (7) found urinary retention in 17% of 348 children receiving epidural analgesia. Recently, Tsui et al. (15) reported an incidence of 20.8%. The authors did not specify whether urinary retention was associated with lumbar or thoracic epidural catheters. Brenn et al. (28) noted that 70% of children with continuous epidural analgesia required postoperative catheterization for urinary retention. Although Wood et al. (14) reported a 5.3% incidence of patients with urinary retention related to the use of continuous epidural analgesia, many of the patients in their study had undergone urological procedures and had urinary catheters in situ. In our study, urinary retention was more frequent in the CEB group (33%) than in the CPNB groups. It is of interest that one child with a popliteal nerve catheter had urinary retention. This episode occurred at the first postoperative hour and was probably related to IV fentanyl during anesthesia.
Premature discontinuation of LA infusion occurs commonly with continuous epidural infusions in children (12,14,15). The overall incidence reported in our study population (22.22%) is similar to that reported by others. Wood et al. (14) reported premature discontinuation of epidural infusions in 41 of 190 epidurals (21.57%), mainly as a result of leakage of solution around the entry site of the catheter or catheter occlusion. Jylli et al. (12) found 37% of epidural infusions were discontinued prematurely and that catheter dislodgement or leakage was the primary cause. In the 1- to 6-year-old group in our study, the incidence of premature discontinued LA infusion was significantly more frequent in the CEB groups (29.4%) compared with the CPNB groups (0%).
Pruritus related to epidural analgesia occurs in 0% to 88% of pediatric patients (9,11,14,19). We documented an incidence of 7.4% in the CEB groups and 12% in the CPNB groups. Pruritus is reported most frequently with the use of LA with morphine (14,19) and is rarely described with LA only. In our study, the episodes of pruritus were related to the use of rescue analgesia with nalbuphine.
CEB causes bilateral motor blockade, which is unnecessary for patients having unilateral surgery (29). In this study, all patients were reported to have effective analgesia and none had any motor block after 6 hours. The use of a small dose and small concentration of ropivacaine allowed for this differential blockade (3,30). Wood et al. (14) emphasize the fact that intense motor block increases the risk of patients developing pressure sores. The same authors also emphasize the importance of treating motor blockade by adjusting the solutions concentration or rate of administration.
In conclusion, the present study demonstrated that CPNB with 0.2% ropivacaine provided optimal postoperative pain management in children undergoing major podiatric surgery. This study also highlights the advantage of CPNB over CEB with respect to adverse events and pain relief, especially in children aged 7 to 12 years. CPNB decreased the incidence of nausea and vomiting, urinary retention, and premature discontinuation of LA infusion. Although we observed, in some patients, a minor degree of unilateral motor blockade, the quality of postoperative pain relief and high parental satisfaction serve to demonstrate the utility of this technique in children.
| Footnotes |
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Supported, in part, by the Association pour le Développement et la Recherche en Anesthésie Réanimation, CHU Lapeyronie, Montpellier, France.
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