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Ultrasound-guided bilateral rectus sheath block vs. conventional local analgesia in single port laparoscopic appendectomy for children with nonperforated appendicitis
Journal of Pediatric Surgery 53 (2018) 431–436
Contents lists available at ScienceDirect
Journal of Pediatric Surgery journal homepage: www.elsevier.com/locate/jpedsurg
Ultrasound-guided bilateral rectus sheath block vs. conventional local analgesia in single port laparoscopic appendectomy for children with nonperforated appendicitis Caroline Maloney a, Michelle Kallis a, Ibrahim Abd El-Shafy a, Aaron M. Lipskar a,b, John Hagen c, Michelle Kars c,⁎ a b c
Department of Surgery, Hofstra Northwell School of Medicine, 300 Community Drive Manhasset, New York 11030 Department of Pediatric Surgery, Northwell Cohen Children's Medical Center, 269-01 76th Ave, New Hyde Park, NY 11040 Department of Anesthesia, Northwell Cohen Children's Medical Center, 269-01 76th Ave, New Hyde Park, NY 11040
a r t i c l e
i n f o
Article history: Received 7 February 2017 Received in revised form 15 May 2017 Accepted 28 May 2017 Key words: Regional anesthesia Appendectomy Minimally-invasive Pediatric Rectus sheath block Ultrasound-guided
a b s t r a c t Introduction: Despite its minimally invasive approach, laparoscopic surgery can cause considerable pain. Regional analgesic techniques such as the rectus sheath block (RSB) offer improved pain management following elective umbilical hernia repair in the pediatric population. This effect has not been examined in laparoscopic singleincision surgery in children. We sought to compare the efficacy of bilateral ultrasound-guided RSB versus local anesthetic infiltration (LAI) in providing postoperative pain relief in pediatric single-incision transumbilical laparoscopic assisted appendectomy (TULA) with same-day discharge. Methods: We retrospectively reviewed 275 children, ages 4 to 17 years old, who underwent TULA for uncomplicated appendicitis in a single institution from August 2014 to July 2015. We compared those that received preincision bilateral RSB (n = 136) with those who received LAI (n = 139). The primary outcome was narcotic administration. Secondary outcomes included initial and mean scores, time from anesthesia induction to release, operative time, time to rescue dose of analgesic in the PACU and time to PACU discharge. Results: Total narcotic administration was significantly reduced in patients that underwent preincision RSB compared to those that received conventional LAI, with a mean of 0.112 mg/kg of morphine versus 0.290 mg/kg morphine (p b 0.0001). Patients undergoing RSB reported lower initial (0.38 vs. 2.38; p b 0.0001) and mean pain scores (1.26 vs. 1.77; p b 0.015). Time to rescue analgesia was prolonged in patients undergoing RSB compared to LAI (58.93 min vs. 41.56 min; p = 0.047). Conclusion: Preincision RSB for TULA in uncomplicated appendicitis in children is associated with decreased opioid consumption and lower pain scores compared with LAI. As the addition of this procedure only added 6.67 min to time under anesthesia, we feel that it is a viable option for postoperative pain control in pediatric singleincision laparoscopic surgery. Retrospective comparative study: LEVEL III EVIDENCE. © 2017 Elsevier Inc. All rights reserved.
Management of perioperative pain often requires the use of opioid medications in order to provide appropriate analgesia. In an attempt to reduce the amount of opioids needed to provide effective postoperative pain control, we have been utilizing regional analgesic techniques more consistently. The rectus sheath block (RSB) is a regional anesthetic technique that works by anesthetizing the ventral rami of T7–T12, the somatic nerves supplying the umbilical area. Several trials have demonstrated the safety and efficacy of RSB in reducing postoperative pain in elective open umbilical hernia repair [1–4]. In 2015 Hamill et al. ⁎ Corresponding author at: Department of Anesthesia, Northwell Cohen Children's Medical Center, 269-1 76th Ave, New Hyde Park, NY 11040, United States. E-mail address: [email protected] (M. Kars). http://dx.doi.org/10.1016/j.jpedsurg.2017.05.027 0022-3468/© 2017 Elsevier Inc. All rights reserved.
examined RSB in traditional pediatric laparoscopic appendectomy using a three-port approach and found that the technique decreased pain scores but did not impact opioid requirements [5]. At our institution the surgical approach to pediatric appendicitis has been a laparoscopic single-incision appendectomy where the appendix is mobilized and removed through a solitary port in the umbilicus. In cases of uncomplicated appendicitis the majority are discharged the same day. While RSB has been examined in the adult population for singleincision cholecystectomy and gynecologic procedures, its use in pediatric single-incision surgery has not been explored [6,7]. In 2014, the anesthetic management of children undergoing single-incision appendectomy for appendicitis at our institution evolved to include bilateral US-guided RSB in addition to general anesthesia.
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The goal of this study was to compare the outcomes of cases in which the US-guided RSB was performed during single-incision laparoscopic appendectomy for nonperforated appendicitis in children with cases in which local analgesic infiltration (LAI) was utilized. The primary aim was to elucidate whether this approach could provide effective analgesia compared to traditional local analgesic administration as evidenced by reduced opioid consumption. We hypothesized that the dermatomal distribution provided by the RSB would be particularly effective in pediatric single-incision transumbilical laparoscopic appendectomy with same-day discharge, reducing opioid consumption and postoperative pain scores. 1. Methods In this retrospective chart review, data were collected from a prospectively maintained billing database from the division of pediatric surgery at a single tertiary care children's hospital from July 2014 to August 2015. Approval was obtained from Cohen Children's Medical Center's institutional review board prior to data collection. A total of 500 patients that underwent appendectomy for appendicitis were identified. Exclusion criteria included all gangrenous or perforated appendicitis (based on pathologic analysis), surgery utilizing a traditional 3-port approach, and children that stayed overnight for antibiotics, leaving 275 patients for analysis. Since 2011, our surgical approach to pediatric appendicitis has been a transumbilical single-incision laparoscopic appendectomy (TULA). Laparoscopic access to the abdomen is obtained through a single incision in the umbilicus to allow for a 12 mm trocar. A 10 mm right-angle laparoscope allows for visualization and for a single working instrument to be inserted. Any retroperitoneal adhesions are mobilized laparoscopically and the appendix is extracorporealized through the umbilicus and resected at the level of the skin (Fig. 1). It is common practice to discharge these patients the day of surgery. At this institution seven different pediatric surgeons perform this operation in equal numbers.
All children received either preincision bilateral ultrasound-guided rectus sheath blocks by the anesthesiologist or local analgesic infiltration into the surgical wound by the surgical team. The execution of the RSB was based on whether the attending anesthesiologist assigned to the procedure was skilled in performing the RSB. In cases where RSB was performed, the abdominal wall was cleansed with 2% chlorhexadine gluconate and the ultrasound probe was used to identify the rectus sheath just cephalad to the umbilicus. The probe was moved laterally until the lateral border of the rectus abdominis muscle was identified and a 22-gauge needle was used for an in-plane technique (Fig. 2). Either 0.25% bupivacaine or 0.5% bupivacaine was injected in the posterior rectus sheath on each side (for a total of 1 ml/kg or 0.5 ml/kg, respectively). For the cases where local analgesia was administered by the surgeon, patients received a subcutaneous injection at the surgical site of either 0.25% or 0.5% bupivacaine at a maximal dose of 1 ml/kg or 0.5 ml/kg, respectively. Whether the local analgesia was administered before or after surgical incision was based on surgeon preference. The total volume administered was variable and rarely was greater than 10 mL. The primary outcome was total opioid administration (in mg/kg of morphine equivalents) for hospital length of stay. Secondary outcomes were intraoperative and postoperative opioid administration, initial and mean pain scores, operative and postoperative administration of nonnarcotic analgesia, time to first rescue dose of analgesia in the post anesthesia care unit in minutes (PACU) and length of stay in the PACU in minutes. Pain scores were assigned by PACU nurses using a numerical age-appropriate visual analog scale (FACES age b 12 years or VAS pain scale N 12 years). Administration of narcotic and non-narcotic analgesia intraoperatively was determined by the attending anesthesiologist and obtained from the anesthesia record. PACU administration of all analgesics was performed by nursing staff based on pain scores. Time from anesthesia induction to anesthesia release defined the time (in minutes) from induction of general anesthesia, including endotracheal intubation, to the
Fig. 1. Transumbilical laparoscopic-assisted appendectomy (TULA) procedure. (A) Laparoscopic mobilization of the appendix utilizing 10 mm working port placed in umbilicus. (B) Removal of appendix through umbilicus and (C) extracorporeal appendectomy. (D) Typical appearance of abdomen post procedure.
C. Maloney et al. / Journal of Pediatric Surgery 53 (2018) 431–436
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Fig. 2. Ultrasound-guided administration of rectus sheath block.
time of surgical incision. The time required for placement of the RSB is included within the time from anesthesia induction to release. This variable and operative time were obtained from the anesthesia record. 1.1. Statistical analysis Continuous variables were summarized using means and standard deviations. The Student's t-test or Wilcoxon (Mann–Whitney) was used to assess group differences. Dichotomous measures were reported as percentages and were assessed using the Pearson's Chi-square statistic or Fisher's Exact test.
narcotics during the operation while all of those that underwent local analgesia infiltration received some form of narcotic (p b 0.0001; 95% CI, 1.405 to 1.823, Table 2). Time to rescue dose of analgesia was prolonged in the group that received a rectus sheath block by 17.8 min compared to local analgesic infiltration (58.93 min ± 8.15 vs. 41.56 min ± 4.29; p = 0.047, Table 2). Postoperative opioid consumption was also significantly reduced in the RSB group compared to the local analgesia group (0.04 mg/kg morphine ± 0.005 vs. 0.06 mg/kg ± 0.006; p = 0.024, Fig. 3B). Total administration of intravenous ketorolac and acetaminophen in the PACU did not differ between the groups. While intraoperative ketorolac administration did not differ significantly between groups, the rectus
2. Results 2.1. Study population Out of the 500 children undergoing appendectomy at Cohen Children's Medical Center from August 2014 to July 2015, 275 children met inclusion criteria for this study with 139 children receiving LAI and 136 receiving bilateral ultrasound-guided RSB. Mean age was 11.4 years (range 4 to 17 years). There were no significant differences in patient demographics including age, sex, race, weight BMI, or ASA classification (Table 1). Additionally, operative time was similar for both groups. The addition of the rectus sheath block added an average of 6.67 min (p b 0.0001) to the total time under general anesthesia compared to local analgesia infiltration. No adverse events requiring immediate medical attention associated with either the block or with LAI were reported. 2.2. Opioid and nonopioid analgesia administration Intraoperative opioid administration was significantly reduced more than three fold in children that underwent bilateral rectus sheath block (Fig. 3A) with 0.068 mg/kg (±0.007) of morphine in the RSB group vs. 0.226 mg/kg (±0.009) in the LAI group (p b 0.0001). Additionally, 44% of patients that underwent rectus sheath block did not receive any
Table 1 Demographics and clinical characteristics of 275 patients reviewed for this study.
Age, mean (SD), yr Male sex, % Weight, mean (SD), kg BMI, mean (SD) ASA class, No. (%) I II III Race, No. (%) White African American Asian Other Unknown Operative time, mean (SD), min
LAI (n = 139)
RSB (n = 136)
P value
11.27 (3.4) 83/139 (60) 47.5 (20.7) 21.1 (6.3)
11.65 (3.3) 84/136 (62) 47.9 (17.6) 20.8 (4.9)
0.394 0.805 0.301 0.671
97 (70) 42 (30) 0 (0)
101 (74) 34 (25) 2 (2)
0.423 0.348 0.244
64 (46) 13 (9) 19 (14) 33 (2) 10 (7) 33.8 (11.2)
64 (47) 9 (7) 10 (7) 39 (3) 14 (10) 32.8 (10.5)
0.904 0.506 0.116 0.411 0.399 0.459
Data represented as mean and standard deviation. Student's t-test was utilized to calculate the difference between means. Dichotomous measures were reported as percentages and were assessed using the Pearson's Chi-square statistic or Fisher's Exact test. BMI, body mass index (calculated as weight in grams divided by height in meters squared); ASA, American Society of Anesthesiologists.
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Fig. 3. RSB decreased narcotic administration compared to LAI. (A) Total intraoperative narcotic. (B) Total narcotic administered in the PACU. (C) Cumulative narcotic administration for length of stay. Unpaired student's t-test *p b 0.05; **p b 0.00. Error bars represent standard error of mean (SEM).
sheath block group did receive more intravenous acetaminophen (11.7 mg/kg ± 5.7 vs. 5.6 mg/kg ± 7.5; p b 0.0001, Table 2). Cumulative narcotic administration for hospital length of stay was significantly less in the rectus sheath block group (0.11 mg/kg morphine ± 0.009 vs. 0.29 mg/kg ± 0.01, p b 0.0001, Fig. 3C). Furthermore 17.8% of children in the rectus sheath block group did not receive any narcotic during their hospital stay while all children in the local analgesia group received narcotics (p b 0.0001, 95% CI 0.001094 to 0.3042).
2.3. Pain scores reported in the PACU The first pain score reported in the PACU was significantly lower for the RSB group compared to the LAI group (0.38 ± 0.15 vs. 2.38 ± 0.27; p b 0.0001, Fig. 4A). Mean pain score was also lower in the RSB group (1.26 ± 0.17 vs. 1.77 ± 0.13; p b 0.015, Fig. 4B). The percentage of children reporting no pain (visual analog score of 0) during their hospital stay was significantly higher in the RSB group with 62 of 136 (45.6%) in the RSB group reporting no pain vs. 32 of 139 (23.0%) in the LAI group reporting no pain (p b 0.001, 95% CI 0.2123 to 0.6001, Table 2).
2.4. Length of stay in PACU While all children were discharged within 24 h following surgery, we found no significant differences in length of stay (minutes) in the PACU postoperatively (170 min ± 7.25 in the LAI group vs. 168 min ± 7.77 in the RSB group, Table 2). 3. Discussion Evidence-based guidelines advocate for the incorporation of enhanced recovery programs including standardization of anesthetic administration, conservative fluid management, and postoperative analgesia into surgery protocols. These programs have been shown to reduce hospital length of stay and facilitate the rapid resumption of normal activities after elective surgery in the adult population, but have not been well studied in pediatric surgery [8,9]. The use of regional analgesia supports these enhanced recovery protocols by reducing the surgical stress response, postoperative pain and the perioperative administration of opiate medications, all of which can negatively impact surgical outcomes and recovery time [9].
Table 2 Primary and secondary outcome measures.
% Receiving no intraoperative narcotic % Receiving no narcotics (LOS) Time to rescue analgesic (min), mean (SD) Anes. induction to release, min, mean (SD) % reporting no pain Total ketorolac (mg/kg), mean (SD) Total IV acetaminophen (mg/kg), mean (SD) PACU IV acetaminophen (mg/kg), mean (SD) PACU LOS, min, mean (SD)
LAI (n = 139)
RSB (n = 136)
P value
0/139 (0%) 0/139 (0%) 41.8 (40.8) 5.2 (3.1) 32/139 (23%) 0.38 (0.24) 6.69 (7.5) 1.12 (3.7) 170 (85.5)
60/136 (44%) 24/136 (17.8%) 59.6 (69.5) 11.8 (10.1) 62/136 (46%) 0.41 (0.24) 12.32 (5.7) 0.619 (2.7) 168 (90.7)
b0.0001 b0.0001 0.047 b0.0001 b0.0001 0.338 b0.0001 0.238 0.83
Data represented as a mean and standard deviation. Student's t-test or Wilcoxon (Mann–Whitney) was utilized to calculate the difference between means. Dichotomous measures were reported as percentages and were assessed using the Pearson's Chi-square statistic or Fisher's Exact test. LOS, length of hospital stay; PACU, postanesthetic care unit.
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Fig. 4. RSB decreased postoperative pain scores compared to LAI. (A) Initial pain scores. (B) Mean pain scores for length of stay. Unpaired student's t- test *p b 0.05; **p b 0.0001. Error bars represent SEM.
Several studies have examined the benefits of the RSB in elective pediatric umbilical hernia repair [1–4]. Dingeman et al. described the utilization of RSB when compared to local anesthetic infiltration (LAI) for umbilical hernia repairs, improving pain scores in the postanesthesia care unit (PACU) [1]. However, both the RSB and LAI were performed at the completion of the surgical procedure prior to extubation. Our study examines the effect of RSB used as a preemptive analgesic. Evaluation of this technique in acute laparoscopic surgery has been limited. A literature search found one study that examined the use of ultrasound-guided RSB in laparoscopic appendectomy in children [3]. In this prospective randomized trial, Hamill et al. compared bilateral RSB to local analgesia infiltration in traditional three-port appendectomy for both nonperforated and perforated appendicitis. They found that RSB reduced pain scores in the first 3 h postoperatively but did not see a significant effect thereafter. Furthermore, they did not see a difference in opioid administration between the groups. These results can likely be explained by the fact that a bilateral RSB alone does not offer ideal coverage for suprapubic and left lower quadrant incisions; for better coverage with regional techniques, supplementation with either an additional transverse abdominal plane block or LAI by surgeon to cover all remaining port sites is necessary. Our experience with bilateral ultrasound guided RSB in single incision transumbilical laparoscopic appendectomy for nonperforated appendicitis is the largest reported to date and is the first to investigate the use of the RSB in single-incision laparoscopic surgery in children. In contrast to prior studies, our analysis included only patients that underwent a single-incision surgical technique with same-day discharge. This allowed us to selectively look at the effect of the RSB on the abdominal pain generated by the solitary 12 mm umbilical port, eliminating the confounding effect of the additional ports used in traditional laparoscopic appendectomy. Additionally, our study utilized RSB after the induction of anesthesia, but prior to surgical incision providing preemptive analgesia allowing the opportunity to examine the effect of RSB on intraoperative opioid administration. Our data demonstrate a significant reduction in intraoperative narcotic administration in the RSB group, with 40% of children requiring no intraoperative narcotic compared to children in the LAI group who all required narcotic during the case. Taken together these data suggest that administering RSB prior to incision can successfully reduce the amount of intraoperative narcotic needed and in some cases obviate the need for intraoperative narcotic altogether. When examining postoperative narcotic use, significantly less opioid was consumed in the PACU in the RSB group compared with the LAI group, as was cumulative narcotic use for total hospital length of stay. As this study captures our institution's initial experience performing the RSB we hypothesized that the group undergoing the RSB earlier in the time course of the study would have more instances of “block failure” and require more
narcotics. This was not the case as these patients were evenly distributed throughout the time of the study. Time to first rescue dose of analgesia in the PACU averaged at approximately 59 min in the RSB group, nearly 20 min longer than that of the LAI group. This is significantly longer than that reported by Gurnaney et al. who found that time to rescue analgesia after pediatric umbilical hernia repair with RSB was 36.9 min [4]. Nearly 18% of children in the RSB group received no narcotic during their hospital stay while all children in the LAI group received some form of narcotic. Pain scores in the PACU also reflected decreased overall discomfort with first pain scores, as well as mean pain scores, significantly lower in the RSB group. Perhaps most dramatically, 46% of children reported no pain during their hospital stay compared to 23% in children that underwent LAI. The total amount of non-narcotic analgesia administered was accounted for and while there was no difference in total ketorolac, there was a significant difference in IV acetaminophen with the RSB receiving more drug intraoperatively. In order to have a better understanding of whether the differences in postoperative pain could be attributable to this difference in acetaminophen dosing, we have performed a subgroup analysis examining those RSB patients who received no intraoperative narcotics comparing them to RSB that did. RSB patients that received no intraoperative narcotics received equivalent doses of IV acetaminophen intraoperatively compared to RSB that did receive narcotics (13.13 ± 4.15 vs. 11.17 ± 5.92 mg/kg; p = 0.07). However, RSB patients that received no intraoperative narcotics had significantly lower initial pain scores in the PACU compared to those that did (0.05 ± 0.4 vs. 0.60 ± 2.15; p = 0.034) and to those that underwent LAI (0.05 ± 0.4 vs. 2.4 ± 0.23; p b 0.001). This is despite all groups receiving statistically equivalent doses of non-narcotic analgesia in the PACU. In regards to feasibility, we examined the additional time under anesthesia that performing the RSB required. In order to determine the time that it takes for the RSB to be placed, we subtracted time from anesthesia induction to anesthesia release in the LAI group from the RSB group. We found that the procedure only added 6.67 min to the average operative time of about 33 min without any increase in adverse events. This value may overestimate the actual time required to place the RSB as time from anesthesia induction to release encompasses the time from endotracheal intubation to surgical incision. Additionally these data included the first RSB ever performed at our institution, as well as anesthesiologists and residents with varying degrees of experience performing the procedure. We believe that since the RSB has increasingly become the standard at our institution, individual practitioners have now become more facile performing this procedure and the additional time added under anesthesia has been dramatically reduced. There are some important limitations of this study. First, our data failed to show a difference in PACU length of stay. This is likely owing
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to our institution's PACU discharge policies and protocols. Recovery in the PACU requires a set number of vital signs at specific intervals before patients can be discharged from the PACU. Children are discharged at the earliest time unless there is an adverse event, so the fact that there is no difference between the two groups in this study likely only serves to show noninferiority of RSB in this regard. Because the timing of LAI administration was not standardized and based on surgeon's preference, we performed a subgroup analysis comparing local analgesia administered prior to surgical incision versus that administered at the end of the case. We saw no statistically significant differences between total intraoperative or postoperative narcotic administered, first or mean pain scores between groups. Comparing RSB to LAI revealed statistically significant differences in these parameters regardless of whether the LAI was administered prior to or after incision. Additionally, owing to our study's retrospective nature there is inherent observer bias. The anesthesiologist performing the RSB was often the anesthesiologist for the remainder of the operation. Reduction in total intraoperative narcotic is therefore potentially reflective of the anesthesiologist applying a restrictive approach to opioid administration to a patient that received regional analgesia. In future studies we plan to additionally examine physiologic responses to pain during the operation such as heart rate and blood pressure variations. We are currently planning a prospective randomized trial in which the anesthesiologist would be blinded as to which patients have received a RSB. Lastly, our study was limited in that we only examined patients that underwent single-incision appendectomy for uncomplicated appendicitis that were discharged on the day of their surgery and a recent meta-analysis of RSB and TAP blocks in children reported that reductions in morphine requirements as well as pain scores were generally transient and limited to the first 6–8 h after surgery [10]. All narcotic use and pain data in our study were collected while the patients were within the hospital and no at-home data were acquired. In future studies we would examine the duration of analgesia with at-home follow up.
4. Conclusion Bilateral US-guided rectus sheath block appears to be an effective and safe technique that improves postoperative pain and potentially limits opioid consumption in children undergoing single-incision laparoscopic surgery with same-day discharge for nonperforated appendicitis. As most anesthesiologists at our institution were independently performing successful blocks after 5–10 supervised procedures – regardless of baseline ultrasound skill and knowledge of sono-anatomy – we believe that US-guided bilateral RSB could be a valuable addition to the armamentarium of perioperative multimodal pain management. References [1] Dingeman RS, Barus LM, Chung HK, et al. Ultrasonography-guided bilateral rectus sheath block vs local anesthetic infiltration after pediatric umbilical hernia repair. JAMA Surg 2013;148(8):707. [2] Bhalla T, Sawardekar A, Dewhirst E, et al. Ultrasound-guided trunk and core blocks in infants and children. J Anesth 2012;27(1):109–23. [3] Flack SH, Martin LD, Walker BJ, et al. Ultrasound-guided rectus sheath block or wound infiltration in children: a randomized blinded study of analgesia and bupivacaine absorption. Paediatr Anaesth 2014;24:968–73. [4] Gurnaney HG, Maxwell LG, Kraemer FW, et al. Prospective randomized observerblinded study comparing the analgesic efficacy of ultrasound-guided rectus sheath block and local anaesthetic infiltration for umbilical hernia repair. Br J Anaesth 2011;107:790–5. [5] Hamill JK, Liley A, Hill AG. Rectus sheath block for laparoscopic appendicectomy: a randomized clinical trial. ANZ J Surg 2015;85:951–6. [6] Kamei H, Ishibashi N, Nakayama G, et al. Ultrasound-guided rectus sheath block for single-incision laparoscopic cholecystectomy. Asian J Endosc Surg 2015;8:148–52. [7] Mugita M, Kawahara R, Tamai Y, et al. Effectiveness of ultrasound-guided transversus abdominis plane block and rectus sheath block in pain control and recovery after gynecological transumbilical single incision laparoscopic surgery. Clin Exp Obstet Gynecol 2014;41:627–32. [8] Russell P, Ungern-Sternberg BSV, Schug SA. Perioperative analgesia in pediatric surgery. Curr Opin Anaesthesiol 2013;26(4):420–7. [9] Bosenberg A. Benefits of regional anesthesia in children. Pediatr Anesth 2011 Jul; 22(1):10–8. [10] Hamill JK, Rahiri JL, Liley A, et al. Rectus sheath and transversus abdominis plane blocks in children: a systematic review and meta-analysis of randomized trials. Paediatr Anaesth 2016;26(4):363–71.
Contents lists available at ScienceDirect
Journal of Pediatric Surgery journal homepage: www.elsevier.com/locate/jpedsurg
Ultrasound-guided bilateral rectus sheath block vs. conventional local analgesia in single port laparoscopic appendectomy for children with nonperforated appendicitis Caroline Maloney a, Michelle Kallis a, Ibrahim Abd El-Shafy a, Aaron M. Lipskar a,b, John Hagen c, Michelle Kars c,⁎ a b c
Department of Surgery, Hofstra Northwell School of Medicine, 300 Community Drive Manhasset, New York 11030 Department of Pediatric Surgery, Northwell Cohen Children's Medical Center, 269-01 76th Ave, New Hyde Park, NY 11040 Department of Anesthesia, Northwell Cohen Children's Medical Center, 269-01 76th Ave, New Hyde Park, NY 11040
a r t i c l e
i n f o
Article history: Received 7 February 2017 Received in revised form 15 May 2017 Accepted 28 May 2017 Key words: Regional anesthesia Appendectomy Minimally-invasive Pediatric Rectus sheath block Ultrasound-guided
a b s t r a c t Introduction: Despite its minimally invasive approach, laparoscopic surgery can cause considerable pain. Regional analgesic techniques such as the rectus sheath block (RSB) offer improved pain management following elective umbilical hernia repair in the pediatric population. This effect has not been examined in laparoscopic singleincision surgery in children. We sought to compare the efficacy of bilateral ultrasound-guided RSB versus local anesthetic infiltration (LAI) in providing postoperative pain relief in pediatric single-incision transumbilical laparoscopic assisted appendectomy (TULA) with same-day discharge. Methods: We retrospectively reviewed 275 children, ages 4 to 17 years old, who underwent TULA for uncomplicated appendicitis in a single institution from August 2014 to July 2015. We compared those that received preincision bilateral RSB (n = 136) with those who received LAI (n = 139). The primary outcome was narcotic administration. Secondary outcomes included initial and mean scores, time from anesthesia induction to release, operative time, time to rescue dose of analgesic in the PACU and time to PACU discharge. Results: Total narcotic administration was significantly reduced in patients that underwent preincision RSB compared to those that received conventional LAI, with a mean of 0.112 mg/kg of morphine versus 0.290 mg/kg morphine (p b 0.0001). Patients undergoing RSB reported lower initial (0.38 vs. 2.38; p b 0.0001) and mean pain scores (1.26 vs. 1.77; p b 0.015). Time to rescue analgesia was prolonged in patients undergoing RSB compared to LAI (58.93 min vs. 41.56 min; p = 0.047). Conclusion: Preincision RSB for TULA in uncomplicated appendicitis in children is associated with decreased opioid consumption and lower pain scores compared with LAI. As the addition of this procedure only added 6.67 min to time under anesthesia, we feel that it is a viable option for postoperative pain control in pediatric singleincision laparoscopic surgery. Retrospective comparative study: LEVEL III EVIDENCE. © 2017 Elsevier Inc. All rights reserved.
Management of perioperative pain often requires the use of opioid medications in order to provide appropriate analgesia. In an attempt to reduce the amount of opioids needed to provide effective postoperative pain control, we have been utilizing regional analgesic techniques more consistently. The rectus sheath block (RSB) is a regional anesthetic technique that works by anesthetizing the ventral rami of T7–T12, the somatic nerves supplying the umbilical area. Several trials have demonstrated the safety and efficacy of RSB in reducing postoperative pain in elective open umbilical hernia repair [1–4]. In 2015 Hamill et al. ⁎ Corresponding author at: Department of Anesthesia, Northwell Cohen Children's Medical Center, 269-1 76th Ave, New Hyde Park, NY 11040, United States. E-mail address: [email protected] (M. Kars). http://dx.doi.org/10.1016/j.jpedsurg.2017.05.027 0022-3468/© 2017 Elsevier Inc. All rights reserved.
examined RSB in traditional pediatric laparoscopic appendectomy using a three-port approach and found that the technique decreased pain scores but did not impact opioid requirements [5]. At our institution the surgical approach to pediatric appendicitis has been a laparoscopic single-incision appendectomy where the appendix is mobilized and removed through a solitary port in the umbilicus. In cases of uncomplicated appendicitis the majority are discharged the same day. While RSB has been examined in the adult population for singleincision cholecystectomy and gynecologic procedures, its use in pediatric single-incision surgery has not been explored [6,7]. In 2014, the anesthetic management of children undergoing single-incision appendectomy for appendicitis at our institution evolved to include bilateral US-guided RSB in addition to general anesthesia.
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C. Maloney et al. / Journal of Pediatric Surgery 53 (2018) 431–436
The goal of this study was to compare the outcomes of cases in which the US-guided RSB was performed during single-incision laparoscopic appendectomy for nonperforated appendicitis in children with cases in which local analgesic infiltration (LAI) was utilized. The primary aim was to elucidate whether this approach could provide effective analgesia compared to traditional local analgesic administration as evidenced by reduced opioid consumption. We hypothesized that the dermatomal distribution provided by the RSB would be particularly effective in pediatric single-incision transumbilical laparoscopic appendectomy with same-day discharge, reducing opioid consumption and postoperative pain scores. 1. Methods In this retrospective chart review, data were collected from a prospectively maintained billing database from the division of pediatric surgery at a single tertiary care children's hospital from July 2014 to August 2015. Approval was obtained from Cohen Children's Medical Center's institutional review board prior to data collection. A total of 500 patients that underwent appendectomy for appendicitis were identified. Exclusion criteria included all gangrenous or perforated appendicitis (based on pathologic analysis), surgery utilizing a traditional 3-port approach, and children that stayed overnight for antibiotics, leaving 275 patients for analysis. Since 2011, our surgical approach to pediatric appendicitis has been a transumbilical single-incision laparoscopic appendectomy (TULA). Laparoscopic access to the abdomen is obtained through a single incision in the umbilicus to allow for a 12 mm trocar. A 10 mm right-angle laparoscope allows for visualization and for a single working instrument to be inserted. Any retroperitoneal adhesions are mobilized laparoscopically and the appendix is extracorporealized through the umbilicus and resected at the level of the skin (Fig. 1). It is common practice to discharge these patients the day of surgery. At this institution seven different pediatric surgeons perform this operation in equal numbers.
All children received either preincision bilateral ultrasound-guided rectus sheath blocks by the anesthesiologist or local analgesic infiltration into the surgical wound by the surgical team. The execution of the RSB was based on whether the attending anesthesiologist assigned to the procedure was skilled in performing the RSB. In cases where RSB was performed, the abdominal wall was cleansed with 2% chlorhexadine gluconate and the ultrasound probe was used to identify the rectus sheath just cephalad to the umbilicus. The probe was moved laterally until the lateral border of the rectus abdominis muscle was identified and a 22-gauge needle was used for an in-plane technique (Fig. 2). Either 0.25% bupivacaine or 0.5% bupivacaine was injected in the posterior rectus sheath on each side (for a total of 1 ml/kg or 0.5 ml/kg, respectively). For the cases where local analgesia was administered by the surgeon, patients received a subcutaneous injection at the surgical site of either 0.25% or 0.5% bupivacaine at a maximal dose of 1 ml/kg or 0.5 ml/kg, respectively. Whether the local analgesia was administered before or after surgical incision was based on surgeon preference. The total volume administered was variable and rarely was greater than 10 mL. The primary outcome was total opioid administration (in mg/kg of morphine equivalents) for hospital length of stay. Secondary outcomes were intraoperative and postoperative opioid administration, initial and mean pain scores, operative and postoperative administration of nonnarcotic analgesia, time to first rescue dose of analgesia in the post anesthesia care unit in minutes (PACU) and length of stay in the PACU in minutes. Pain scores were assigned by PACU nurses using a numerical age-appropriate visual analog scale (FACES age b 12 years or VAS pain scale N 12 years). Administration of narcotic and non-narcotic analgesia intraoperatively was determined by the attending anesthesiologist and obtained from the anesthesia record. PACU administration of all analgesics was performed by nursing staff based on pain scores. Time from anesthesia induction to anesthesia release defined the time (in minutes) from induction of general anesthesia, including endotracheal intubation, to the
Fig. 1. Transumbilical laparoscopic-assisted appendectomy (TULA) procedure. (A) Laparoscopic mobilization of the appendix utilizing 10 mm working port placed in umbilicus. (B) Removal of appendix through umbilicus and (C) extracorporeal appendectomy. (D) Typical appearance of abdomen post procedure.
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Fig. 2. Ultrasound-guided administration of rectus sheath block.
time of surgical incision. The time required for placement of the RSB is included within the time from anesthesia induction to release. This variable and operative time were obtained from the anesthesia record. 1.1. Statistical analysis Continuous variables were summarized using means and standard deviations. The Student's t-test or Wilcoxon (Mann–Whitney) was used to assess group differences. Dichotomous measures were reported as percentages and were assessed using the Pearson's Chi-square statistic or Fisher's Exact test.
narcotics during the operation while all of those that underwent local analgesia infiltration received some form of narcotic (p b 0.0001; 95% CI, 1.405 to 1.823, Table 2). Time to rescue dose of analgesia was prolonged in the group that received a rectus sheath block by 17.8 min compared to local analgesic infiltration (58.93 min ± 8.15 vs. 41.56 min ± 4.29; p = 0.047, Table 2). Postoperative opioid consumption was also significantly reduced in the RSB group compared to the local analgesia group (0.04 mg/kg morphine ± 0.005 vs. 0.06 mg/kg ± 0.006; p = 0.024, Fig. 3B). Total administration of intravenous ketorolac and acetaminophen in the PACU did not differ between the groups. While intraoperative ketorolac administration did not differ significantly between groups, the rectus
2. Results 2.1. Study population Out of the 500 children undergoing appendectomy at Cohen Children's Medical Center from August 2014 to July 2015, 275 children met inclusion criteria for this study with 139 children receiving LAI and 136 receiving bilateral ultrasound-guided RSB. Mean age was 11.4 years (range 4 to 17 years). There were no significant differences in patient demographics including age, sex, race, weight BMI, or ASA classification (Table 1). Additionally, operative time was similar for both groups. The addition of the rectus sheath block added an average of 6.67 min (p b 0.0001) to the total time under general anesthesia compared to local analgesia infiltration. No adverse events requiring immediate medical attention associated with either the block or with LAI were reported. 2.2. Opioid and nonopioid analgesia administration Intraoperative opioid administration was significantly reduced more than three fold in children that underwent bilateral rectus sheath block (Fig. 3A) with 0.068 mg/kg (±0.007) of morphine in the RSB group vs. 0.226 mg/kg (±0.009) in the LAI group (p b 0.0001). Additionally, 44% of patients that underwent rectus sheath block did not receive any
Table 1 Demographics and clinical characteristics of 275 patients reviewed for this study.
Age, mean (SD), yr Male sex, % Weight, mean (SD), kg BMI, mean (SD) ASA class, No. (%) I II III Race, No. (%) White African American Asian Other Unknown Operative time, mean (SD), min
LAI (n = 139)
RSB (n = 136)
P value
11.27 (3.4) 83/139 (60) 47.5 (20.7) 21.1 (6.3)
11.65 (3.3) 84/136 (62) 47.9 (17.6) 20.8 (4.9)
0.394 0.805 0.301 0.671
97 (70) 42 (30) 0 (0)
101 (74) 34 (25) 2 (2)
0.423 0.348 0.244
64 (46) 13 (9) 19 (14) 33 (2) 10 (7) 33.8 (11.2)
64 (47) 9 (7) 10 (7) 39 (3) 14 (10) 32.8 (10.5)
0.904 0.506 0.116 0.411 0.399 0.459
Data represented as mean and standard deviation. Student's t-test was utilized to calculate the difference between means. Dichotomous measures were reported as percentages and were assessed using the Pearson's Chi-square statistic or Fisher's Exact test. BMI, body mass index (calculated as weight in grams divided by height in meters squared); ASA, American Society of Anesthesiologists.
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Fig. 3. RSB decreased narcotic administration compared to LAI. (A) Total intraoperative narcotic. (B) Total narcotic administered in the PACU. (C) Cumulative narcotic administration for length of stay. Unpaired student's t-test *p b 0.05; **p b 0.00. Error bars represent standard error of mean (SEM).
sheath block group did receive more intravenous acetaminophen (11.7 mg/kg ± 5.7 vs. 5.6 mg/kg ± 7.5; p b 0.0001, Table 2). Cumulative narcotic administration for hospital length of stay was significantly less in the rectus sheath block group (0.11 mg/kg morphine ± 0.009 vs. 0.29 mg/kg ± 0.01, p b 0.0001, Fig. 3C). Furthermore 17.8% of children in the rectus sheath block group did not receive any narcotic during their hospital stay while all children in the local analgesia group received narcotics (p b 0.0001, 95% CI 0.001094 to 0.3042).
2.3. Pain scores reported in the PACU The first pain score reported in the PACU was significantly lower for the RSB group compared to the LAI group (0.38 ± 0.15 vs. 2.38 ± 0.27; p b 0.0001, Fig. 4A). Mean pain score was also lower in the RSB group (1.26 ± 0.17 vs. 1.77 ± 0.13; p b 0.015, Fig. 4B). The percentage of children reporting no pain (visual analog score of 0) during their hospital stay was significantly higher in the RSB group with 62 of 136 (45.6%) in the RSB group reporting no pain vs. 32 of 139 (23.0%) in the LAI group reporting no pain (p b 0.001, 95% CI 0.2123 to 0.6001, Table 2).
2.4. Length of stay in PACU While all children were discharged within 24 h following surgery, we found no significant differences in length of stay (minutes) in the PACU postoperatively (170 min ± 7.25 in the LAI group vs. 168 min ± 7.77 in the RSB group, Table 2). 3. Discussion Evidence-based guidelines advocate for the incorporation of enhanced recovery programs including standardization of anesthetic administration, conservative fluid management, and postoperative analgesia into surgery protocols. These programs have been shown to reduce hospital length of stay and facilitate the rapid resumption of normal activities after elective surgery in the adult population, but have not been well studied in pediatric surgery [8,9]. The use of regional analgesia supports these enhanced recovery protocols by reducing the surgical stress response, postoperative pain and the perioperative administration of opiate medications, all of which can negatively impact surgical outcomes and recovery time [9].
Table 2 Primary and secondary outcome measures.
% Receiving no intraoperative narcotic % Receiving no narcotics (LOS) Time to rescue analgesic (min), mean (SD) Anes. induction to release, min, mean (SD) % reporting no pain Total ketorolac (mg/kg), mean (SD) Total IV acetaminophen (mg/kg), mean (SD) PACU IV acetaminophen (mg/kg), mean (SD) PACU LOS, min, mean (SD)
LAI (n = 139)
RSB (n = 136)
P value
0/139 (0%) 0/139 (0%) 41.8 (40.8) 5.2 (3.1) 32/139 (23%) 0.38 (0.24) 6.69 (7.5) 1.12 (3.7) 170 (85.5)
60/136 (44%) 24/136 (17.8%) 59.6 (69.5) 11.8 (10.1) 62/136 (46%) 0.41 (0.24) 12.32 (5.7) 0.619 (2.7) 168 (90.7)
b0.0001 b0.0001 0.047 b0.0001 b0.0001 0.338 b0.0001 0.238 0.83
Data represented as a mean and standard deviation. Student's t-test or Wilcoxon (Mann–Whitney) was utilized to calculate the difference between means. Dichotomous measures were reported as percentages and were assessed using the Pearson's Chi-square statistic or Fisher's Exact test. LOS, length of hospital stay; PACU, postanesthetic care unit.
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Fig. 4. RSB decreased postoperative pain scores compared to LAI. (A) Initial pain scores. (B) Mean pain scores for length of stay. Unpaired student's t- test *p b 0.05; **p b 0.0001. Error bars represent SEM.
Several studies have examined the benefits of the RSB in elective pediatric umbilical hernia repair [1–4]. Dingeman et al. described the utilization of RSB when compared to local anesthetic infiltration (LAI) for umbilical hernia repairs, improving pain scores in the postanesthesia care unit (PACU) [1]. However, both the RSB and LAI were performed at the completion of the surgical procedure prior to extubation. Our study examines the effect of RSB used as a preemptive analgesic. Evaluation of this technique in acute laparoscopic surgery has been limited. A literature search found one study that examined the use of ultrasound-guided RSB in laparoscopic appendectomy in children [3]. In this prospective randomized trial, Hamill et al. compared bilateral RSB to local analgesia infiltration in traditional three-port appendectomy for both nonperforated and perforated appendicitis. They found that RSB reduced pain scores in the first 3 h postoperatively but did not see a significant effect thereafter. Furthermore, they did not see a difference in opioid administration between the groups. These results can likely be explained by the fact that a bilateral RSB alone does not offer ideal coverage for suprapubic and left lower quadrant incisions; for better coverage with regional techniques, supplementation with either an additional transverse abdominal plane block or LAI by surgeon to cover all remaining port sites is necessary. Our experience with bilateral ultrasound guided RSB in single incision transumbilical laparoscopic appendectomy for nonperforated appendicitis is the largest reported to date and is the first to investigate the use of the RSB in single-incision laparoscopic surgery in children. In contrast to prior studies, our analysis included only patients that underwent a single-incision surgical technique with same-day discharge. This allowed us to selectively look at the effect of the RSB on the abdominal pain generated by the solitary 12 mm umbilical port, eliminating the confounding effect of the additional ports used in traditional laparoscopic appendectomy. Additionally, our study utilized RSB after the induction of anesthesia, but prior to surgical incision providing preemptive analgesia allowing the opportunity to examine the effect of RSB on intraoperative opioid administration. Our data demonstrate a significant reduction in intraoperative narcotic administration in the RSB group, with 40% of children requiring no intraoperative narcotic compared to children in the LAI group who all required narcotic during the case. Taken together these data suggest that administering RSB prior to incision can successfully reduce the amount of intraoperative narcotic needed and in some cases obviate the need for intraoperative narcotic altogether. When examining postoperative narcotic use, significantly less opioid was consumed in the PACU in the RSB group compared with the LAI group, as was cumulative narcotic use for total hospital length of stay. As this study captures our institution's initial experience performing the RSB we hypothesized that the group undergoing the RSB earlier in the time course of the study would have more instances of “block failure” and require more
narcotics. This was not the case as these patients were evenly distributed throughout the time of the study. Time to first rescue dose of analgesia in the PACU averaged at approximately 59 min in the RSB group, nearly 20 min longer than that of the LAI group. This is significantly longer than that reported by Gurnaney et al. who found that time to rescue analgesia after pediatric umbilical hernia repair with RSB was 36.9 min [4]. Nearly 18% of children in the RSB group received no narcotic during their hospital stay while all children in the LAI group received some form of narcotic. Pain scores in the PACU also reflected decreased overall discomfort with first pain scores, as well as mean pain scores, significantly lower in the RSB group. Perhaps most dramatically, 46% of children reported no pain during their hospital stay compared to 23% in children that underwent LAI. The total amount of non-narcotic analgesia administered was accounted for and while there was no difference in total ketorolac, there was a significant difference in IV acetaminophen with the RSB receiving more drug intraoperatively. In order to have a better understanding of whether the differences in postoperative pain could be attributable to this difference in acetaminophen dosing, we have performed a subgroup analysis examining those RSB patients who received no intraoperative narcotics comparing them to RSB that did. RSB patients that received no intraoperative narcotics received equivalent doses of IV acetaminophen intraoperatively compared to RSB that did receive narcotics (13.13 ± 4.15 vs. 11.17 ± 5.92 mg/kg; p = 0.07). However, RSB patients that received no intraoperative narcotics had significantly lower initial pain scores in the PACU compared to those that did (0.05 ± 0.4 vs. 0.60 ± 2.15; p = 0.034) and to those that underwent LAI (0.05 ± 0.4 vs. 2.4 ± 0.23; p b 0.001). This is despite all groups receiving statistically equivalent doses of non-narcotic analgesia in the PACU. In regards to feasibility, we examined the additional time under anesthesia that performing the RSB required. In order to determine the time that it takes for the RSB to be placed, we subtracted time from anesthesia induction to anesthesia release in the LAI group from the RSB group. We found that the procedure only added 6.67 min to the average operative time of about 33 min without any increase in adverse events. This value may overestimate the actual time required to place the RSB as time from anesthesia induction to release encompasses the time from endotracheal intubation to surgical incision. Additionally these data included the first RSB ever performed at our institution, as well as anesthesiologists and residents with varying degrees of experience performing the procedure. We believe that since the RSB has increasingly become the standard at our institution, individual practitioners have now become more facile performing this procedure and the additional time added under anesthesia has been dramatically reduced. There are some important limitations of this study. First, our data failed to show a difference in PACU length of stay. This is likely owing
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to our institution's PACU discharge policies and protocols. Recovery in the PACU requires a set number of vital signs at specific intervals before patients can be discharged from the PACU. Children are discharged at the earliest time unless there is an adverse event, so the fact that there is no difference between the two groups in this study likely only serves to show noninferiority of RSB in this regard. Because the timing of LAI administration was not standardized and based on surgeon's preference, we performed a subgroup analysis comparing local analgesia administered prior to surgical incision versus that administered at the end of the case. We saw no statistically significant differences between total intraoperative or postoperative narcotic administered, first or mean pain scores between groups. Comparing RSB to LAI revealed statistically significant differences in these parameters regardless of whether the LAI was administered prior to or after incision. Additionally, owing to our study's retrospective nature there is inherent observer bias. The anesthesiologist performing the RSB was often the anesthesiologist for the remainder of the operation. Reduction in total intraoperative narcotic is therefore potentially reflective of the anesthesiologist applying a restrictive approach to opioid administration to a patient that received regional analgesia. In future studies we plan to additionally examine physiologic responses to pain during the operation such as heart rate and blood pressure variations. We are currently planning a prospective randomized trial in which the anesthesiologist would be blinded as to which patients have received a RSB. Lastly, our study was limited in that we only examined patients that underwent single-incision appendectomy for uncomplicated appendicitis that were discharged on the day of their surgery and a recent meta-analysis of RSB and TAP blocks in children reported that reductions in morphine requirements as well as pain scores were generally transient and limited to the first 6–8 h after surgery [10]. All narcotic use and pain data in our study were collected while the patients were within the hospital and no at-home data were acquired. In future studies we would examine the duration of analgesia with at-home follow up.
4. Conclusion Bilateral US-guided rectus sheath block appears to be an effective and safe technique that improves postoperative pain and potentially limits opioid consumption in children undergoing single-incision laparoscopic surgery with same-day discharge for nonperforated appendicitis. As most anesthesiologists at our institution were independently performing successful blocks after 5–10 supervised procedures – regardless of baseline ultrasound skill and knowledge of sono-anatomy – we believe that US-guided bilateral RSB could be a valuable addition to the armamentarium of perioperative multimodal pain management. References [1] Dingeman RS, Barus LM, Chung HK, et al. Ultrasonography-guided bilateral rectus sheath block vs local anesthetic infiltration after pediatric umbilical hernia repair. JAMA Surg 2013;148(8):707. [2] Bhalla T, Sawardekar A, Dewhirst E, et al. Ultrasound-guided trunk and core blocks in infants and children. J Anesth 2012;27(1):109–23. [3] Flack SH, Martin LD, Walker BJ, et al. Ultrasound-guided rectus sheath block or wound infiltration in children: a randomized blinded study of analgesia and bupivacaine absorption. Paediatr Anaesth 2014;24:968–73. [4] Gurnaney HG, Maxwell LG, Kraemer FW, et al. Prospective randomized observerblinded study comparing the analgesic efficacy of ultrasound-guided rectus sheath block and local anaesthetic infiltration for umbilical hernia repair. Br J Anaesth 2011;107:790–5. [5] Hamill JK, Liley A, Hill AG. Rectus sheath block for laparoscopic appendicectomy: a randomized clinical trial. ANZ J Surg 2015;85:951–6. [6] Kamei H, Ishibashi N, Nakayama G, et al. Ultrasound-guided rectus sheath block for single-incision laparoscopic cholecystectomy. Asian J Endosc Surg 2015;8:148–52. [7] Mugita M, Kawahara R, Tamai Y, et al. Effectiveness of ultrasound-guided transversus abdominis plane block and rectus sheath block in pain control and recovery after gynecological transumbilical single incision laparoscopic surgery. Clin Exp Obstet Gynecol 2014;41:627–32. [8] Russell P, Ungern-Sternberg BSV, Schug SA. Perioperative analgesia in pediatric surgery. Curr Opin Anaesthesiol 2013;26(4):420–7. [9] Bosenberg A. Benefits of regional anesthesia in children. Pediatr Anesth 2011 Jul; 22(1):10–8. [10] Hamill JK, Rahiri JL, Liley A, et al. Rectus sheath and transversus abdominis plane blocks in children: a systematic review and meta-analysis of randomized trials. Paediatr Anaesth 2016;26(4):363–71.