Ilioinguinal/iliohypogastric nerve block with levobupivacaine in children

Despite having a tower toxic threshold than other focal anesthetics, bupivacaine is the most commonly used local anesthetic in children.1 Bupivacaine is currently available only as a racemic mixture; the excess cardiac toxicity of bupivacaine is due to the dextrorotary enantfomer (dexbupivacaine).2 The toxicity profile of the levorotary enantiomer, levobuprvacaine, is similar to that of other local anesthetics. We performed a double-blind, randomized, placebo controlled study to determine the safety and effectiveness of levobupivacaine for field block in children having outpatient herniorrhaphy. METHODS After IRB approval and informed parental consent, otherwise healthy children ages 6 mo to 12 y presenting for outpatient herniorrhaphy were randomized to receive either ilioinguinal/iliohypogastric (IIIH) nerve block(s) with 0.25 ml·kg'1 levobupivacaine per side operated (Group LB) or no block (Group NB) at the completion of surgery; a bandaid was placed over the site of the injection in all subjects to maintain blinding of postoperative observers. All subjects received acetaminophen 15 mgkg~1 PO before surgery and a standard anesthetic consisting of induction with sevoflurane/N2O, maintenance with hatothane/N2O, spontaneous ventilation, metoctopramide 0.2 mg·kg1, and no intraoperative opioids or local anesthetics other than study drug. Subjects were observed in the PACU and a Children's Hospital of Eastern Ontario Pain Score (CHEOPS) was recorded every 5 min for 30 min and every 15 min for an additional 90 min; subjects scoring > 10 on CHEOPS received up tc 3 doses of morphine 0.05 mg·kg'1 and one dose of ketorolac 1 mg·kg'V Time to awakening, vital signs, emesis, quality of block (0=poor, 1=fair, 2=good, 3=excellent) and any adverse events were recorded during the 2 h observation period; parents were contacted by telephone 48 to 72 h after surgery to identify any adverse events. Parametric data are presented as mean ±SD and were compared with Student's t test; non-parametric data were compared with x2, Fisher's Exact Test, or the Mann-Wh'rtney Utest as appropriate. RESULTS 35 subjects were randomized and completed the study . There was no difference in age, weight, gender, or location of surgery between the two groups (Table 1). Differences in time to awakening, quality of block, need for resuce analgesics, and time to rescue analgesics are shown in Table 2; NB subjects required rescue analgesics sooner and in greater amounts than LB subjects. Median CHEOPS are shown in Table 3. Two LB subject had a femoral nerve block and two LB subjects had delayed urination that did not require treatment; one NB subject returned to hospital the evening of surgery for repair of wound dehiscence. COMMENT Levobupivacaine was safe and effective for IIIH block in children having herniorrhaphy as demonstrated by a longer interval to rescue analgesia, fewer rescue analgesic doses, tower CHEOPS at 15,20,30 and 60 min and the absence of any adverse events specifically attributable to levobupivacaine. TABLE 1 No Age Weight Gender Site mo kg M/F L/R/B NB 15 67±38 22.219.9 14/1 5/7/3 LB 20 68±46 23.0±13.4 17/3 7/8/5 TABLE 2 Awaken Quality Rescue Rx # Resc Rx Time to Resc min median Y/N mearttSD min NB 24±16 1 11/4 1.4+1.2 31±12 LB 36±22 2 9/11 0.7±0.9 44117 P 0.077 0.083 0.18 0.058 0.015 TABLES 5min 10min 15min 20min 25min 30min 45min 60min 75min 90min 105min 120min NB 666778776666 LB 666666666666 P NS NS 0.043 0.15 0.043 0.027 0.17 0.036 NS NS NS NS.