Comparison of rectus sheath block and local anesthetic for analgesia in pediatric umbilical hernia repair: A systematic review and meta-analysis

Background:

Pediatric umbilical hernia repair could cause considerable postoperative discomfort. This study aimed to compare the analgesia between rectus sheath block and local anesthetic infiltration in child pediatric umbilical hernia repair.

Methods:

The relevant randomized controlled trials were searched from PubMed, Embase, Web of Science, EBSCO, and Cochrane library databases from its inception to October 2020. The random-effects model was used for meta-analysis.

Results:

Four randomized controlled trials were included in the meta-analysis. The 4 studies were published between 2006 and 2017, with sample sizes ranging from 13 to 52 and a total of 143 individuals across the 4 studies. The Jadad scores of the 4 included studies ranged from 4 to 5, and all 4 studies were considered high quality based on quality assessment. There was no difference in analgesic effect at 10 minutes (standardized mean difference [SMD] = −0.19; 95% confidence interval [CI] = −1.52 to 1.16; P = .78), 30 minutes (SMD = −0.37; 95% CI = −1.53 to 0.78; P = .52), 1 hour (SMD = −0.73; 95% CI = −2.00 to 0.53; P = .26) after surgery. Besides, there was no significant difference in postoperative nausea (risk ratio = 0.95; 95% CI = 0.18 to 5.02; P = .95) and postoperative morphine use in morphine equivalents (mean difference = −0.95; 95% CI = −0.06 to 0.01; P = .12).

Conclusion:

Rectus sheath block and local anesthetic are effective methods for analgesia in pediatric umbilical hernia repair.

1. Introduction

An umbilical hernia is a common childhood disease, and its incidence varies at different ages.^[1] Infants have the highest incidence of umbilical hernias.^[2] Current anesthetic modalities in pediatric umbilical hernias include rectus sheath blocks (RSBs) and local anesthetic infiltration (LAI) of the surgical site. RSB is a technique that provides analgesia to the peritoneum, muscles, and skin of the median anterior abdominal wall incision by injecting local anesthetic between the rectus muscle and the posterior rectus sheath and blocking the nerve that travels between them.^[3,4] It was first applied by Schleich in 1899 to relax the anterior abdominal wall in adults, and in 1996, Ferguson et al used it for analgesia in pediatric hernia repair, but its clinical use was limited due to complications during blind puncture.^[5] In 2006, Wilschke et al pioneered ultrasound-guided RSB.^[6] Recently, with the development of ultrasound equipment and the maturation of puncture techniques, RSB has gained importance in clinical multimodel analgesia. Local infiltration anesthesia is the commonly used clinical anesthesia.^[7] There are many clinical trials on the analgesic effects of the 2 anesthetic modalities after umbilical hernia repair and the effects of anesthetic side effects, but many studies have reached contradictory conclusions.^[8–11] Hamill et al found that RSB and transversus abdominis plane block both reduced pain and opioid use after abdominal surgery in children.^[12] A review article by Jairam et al.^[13] proved local anesthesia for umbilical hernias to be safe and feasible, and there is no evidence-based medical evidence regarding RSB for umbilical hernias. Is local infiltration anesthesia superior to RSB for postoperative analgesia after pediatric hernia repair? We quantitatively aggregated and analyzed relevant randomized controlled trial (RCT) studies to compare the analgesic effects and associated side effects of the 2 anesthetic modalities after pediatric umbilical hernia repair.

Therefore, this study aimed to present the findings from a systematic review of the literature and meta-analysis to compare RSB and the use of LAI for analgesia in pediatric umbilical hernia repair.

2. Material and Methods

This meta-analysis was conducted following the principles of the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) statement and the Cochrane Handbook for Systematic Evaluation of Interventions.^[14,15] All analyses are based on published articles and therefore do not require patient consent and institutional ethics approval.

2.1. Literature search and selection criteria

The literature was searched by 2 researchers in the following databases according to the inclusion criteria: EMBASE, MEDLINE, Cochrane Library, and EBSCO database. The search time frame is from the establishment of the database to October 2020. Use the following keywords to perform the e-search strategy: “Rectus sheath block,” “local anesthetic infiltration,” or “Umbilical hernia repair.” We also screened the full-text study references for inclusion in other potentially eligible studies. Inclusion criteria: (1) The eligible population is patients who have undergone umbilical hernia repair; (2) The intervention is RSB and local anesthetic infiltration; (3) The study design is a RCT; (4) English literature; (5) literature with available data. Besides, we set exclusion criteria are as follows: (1) inguinal hernias in adults (>18 years); (2) duplicate literature; (3) studies in which patients were using potential analgesics (for example, the patient has a high fever); (4) patients with umbilical hernias with other medical conditions.

2.2. Data extraction and outcome measures

We used a tried and tested data extraction form that contained the following information: first author, number of patients, age, female, weight, and detailed methods of intervention treatment for both groups. Data were extracted independently by 2 investigators, and disputes were resolved by negotiation. Where necessary, the corresponding authors were contacted to obtain the data. The primary outcome is pain score at 30 minutes following surgery, and the secondary outcomes include pain score at 10 minutes following surgery, pain score at 1 hour following surgery, postoperative nausea, and postoperative morphine use in morphine equivalents.

2.3. Quality assessment

Different clinical trials were evaluated using the Jadad evaluation scale (0–5 points). The specific evaluation criteria were as follows: generation of randomized sequences (2 points), double-blind method (2 points), and withdrawal and lost visits (1 point).^[16] Those with > 2 points were considered high-quality clinical trials, while those with ≤2 points were considered low-quality clinical trials.^[17]

2.4. Statistical analysis

Meta-analysis was performed using the Rev Man 5.1 software provided by the Cochrane Collaboration Network. Statistical heterogeneity was analyzed using the χ² test, and the significance level was set at P = .10, that is, heterogeneity existed between study results when P < .10. Heterogeneity was also quantitatively assessed using I², which was small for I² ≤ 25%, moderate for > 25% and ≤50%, and large for I² > 50%.^[18] Random-effects models were used to combine the study results. Both interval estimates and hypothesis tests were used for the efficacy effects, with risk ratio used for the count data and standardized mean difference used for the measurement data, and 95% confidence interval (CI) used for the interval estimates; Z and P values were used for the hypothesis tests, and the significance level was set at 0.05, i.e., P < .05 indicated statistically significant differences in the efficacy of different treatments.

3. Results

3.1. Literature search, study characteristics, and quality assessment

Potentially relevant articles were initially identified. Finally, the meta-analysis included 4 RCTs that met the inclusion criteria.

Baseline characteristics of the 4 RCTs in the meta-analysis are summarized in Table 1. The 4 studies were published between 2006 and 2017, with sample sizes ranging from 13 to 52 and a total of 143 individuals across the 4 studies.

Table 1.

Characteristics of included studies.

No. Author	RSB group					LAI group					Jada scores
	Number	Age	Female (n)	Weight (kg)	Methods	Number	Age	Female (n)	Weight (kg)	Methods
1. Gurnaney et al.[9]	26	7.7 (5.1–17.7)	11	27.3 ± 9.9	A predetermined volume of 0.25% bupivacaine was injected for the RSB group	26	7.9 (5.1–16.4)	12	29.8 ± 14.8	The surgeon infiltrated the surgical site with a predetermined volume of 0.25% bupivacaine	26
2. Relland et al[11]	13	4.3 ± 1.6	10	17.5 ± 3.6	RSB group was treated bilaterally with 0.1 ml/kg of 0.2% ropivacaine per side and administered at the T9–T10 level under ultrasound guidance	13	4.6 ± 1.2	6	18.1 ± 2.1	the surgeon injected either 0.5 ml/kg of 0.5% bupivacaine or 1 ml/kg of 0.25% bupivacaine based on the surgeon’s discretion in line with his or her standard practice	13
3. Dingeman et al[10]	27	6.0 ± 2.5	15	26.3 ± 13.3	ultra-sonography-guided RSB (equivalent, volume-adjusted doses of ropivacaine hydrochloride) administered by the pediatric regional anesthesiologist after surgery.	25	6.1 ± 2.4	11	22.3 ± 8.0	the surgeon injected equivalent, volume-adjusted doses of ropivacaine hydrochloride at the site of the incision	25
4. Isaac et al[8]	7	5.9 ± 1.6	13	21.2 ± 6.6	the surgeon used a 2.5-cm short-bevel 24-gauge needle to deliver incrementally a total of 0.15 ml/kg of bupivacaine 0.25% with epinephrine 1:200,000 in a subcutaneous fan-shaped injection, after a negative aspiration test	6	3.9 ± 1.0	11	18.6 ± 5.2	Patients in the local infiltration group received 0.8 ml/kg of 0.25% bupivacaine with epinephrine 1:200,000 infiltrated into the wound by the surgeon	6

LAI = local anesthetic infiltration, RSB = rectus sheath block.

Of the 4 studies, 3 studies reported on the pain score at 10 minutes following surgery^[8,10,11]; 3 studies reported on the pain score at 30 minutes following surgery^[8,10,11]; 2 studies reported on the pain score at 1 hour following surgery^[8,9]; 2 studies reported on the postoperative morphine use in morphine equivalents,^[8,9] and 2 studies reported on postoperative nausea.^[8,9] The Jadad scores of the 4 included studies ranged from 4 to 5, and all 4 studies were considered high quality based on quality assessment.

3.2. Primary outcome: pain score at 30 minutes following surgery

The data were analyzed with a random-effects model. Overall, there was no difference between the RSB and LAI groups, in terms of analgesia 30 minutes after the end of the procedure (standardized mean difference [SMD] = −0.37; 95% CI = −1.53 to 0.78; P = .52; Fig. 1), with high heterogeneity in the results (I² = 83%, P = .003 for heterogeneity) (Fig. 2).

Figure 1.

Flow diagram of study searching and selection process.

Figure 2.

Forest plot for the meta-analysis of pain score at 30 minutes following surgery.

3.3. Sensitivity analysis

Sensitivity analysis of the literature included in the Meta-analysis of the pain score at 30 minutes following surgery showed that the combined results did not change significantly after excluding the included literature item by item, suggesting that the results of this study were relatively stable and that each piece of literature did not have a significant effect on the overall results.

3.4. Secondary outcomes

In the RSB and LAI groups, there was no difference in analgesic effect at 10 minutes (SMD = −0.19; 95% CI = −1.52 to 1.16; P = .78; Fig. 3), 1 hour (SMD = −0.73; 95% CI = −2.00 to 0.53; P = .26; Fig. 4) after the end of the surgery, and no significant difference in postoperative nausea (risk ratio = 0.95; 95% CI = 0.18 to 5.02; P = .95; Fig. 5) and postoperative morphine use in morphine equivalents (mean difference = −0.95; 95% CI = −0.06 to 0.01; P = .12; Fig. 6).

Figure 3.

Forest plot for the meta-analysis of pain score at 10 minutes following surgery.

Figure 4.

Forest plot for the meta-analysis of pain score at 1 hour following surgery.

Figure 5.

Forest plot for the meta-analysis of postoperative nausea.

Figure 6.

Forest plot for the meta-analysis of postoperative morphine use in morphine equivalents.

4. Discussion

This meta-analysis reviewed and analyzed 4 published studies to investigate and compare the analgesic effect of RSB and LAI in child pediatric umbilical hernia repair. The results revealed that RSB and LAI were similarly effective in controlling postoperative pain from umbilical hernia repair.

A randomized, single-blind controlled trial with a sample size of 76 by Takahiro et al^[19] found that the postoperative analgesic effect of RSB in pediatric inguinal hernia repair was comparable to that of LAI, and there was no difference between the 2 groups in the amount of anesthetic medication used within 2 hours of leaving the operating room. Uchinami et al^[20] showed that the analgesic effects of RSB and LAI were similar 30 minutes after leaving the operating room, although the effects throughout the early postoperative period are not known. A randomized, double-blind controlled trial by Relland et al^[11] found no significant differences in analgesic efficacy and postoperative recovery time between RSB and LAI after pediatric umbilical hernia repair. A retrospective study by Kumar et al^[21] showed that RSB and LAI exhibited similar analgesic effects in the perioperative period of infant pyloromyotomy, with no difference in time to discharge and time to first feeding between the 2 groups Lönnqvist’s^[22] study showed that local infiltration anesthesia requires an average dose of 0.8 mL/kg of 2.5 mg/kg. of L⁻¹ bupivacaine. For RSB, only almost half the dose (0.44 mL/kg) is required to achieve the same analgesic effect. The immaturity of liver and kidney function in children and their low plasma protein binding levels make pediatric patients limited in their ability to metabolize local anesthetics. RSB may have tremendous advantages for children, especially infants.

Meanwhile, some studies^[23,24] have found that RSB provides better postoperative analgesia compared to LAI. However, the concentration or total amount of local anesthetic used for RSB in these studies was the same or higher than that used for LAI, and higher concentrations of anesthetic drugs also meant a poorer safety profile for children. In several studies^[10,25] using the same concentration of ropivacaine, RSB provided better analgesia than LAI in the early postoperative period. However, these studies had a high risk of selective bias, small sample sizes, and a high number of study dropouts, resulting in less reliable conclusions. Besides, pain scores in some studies were assessed by the child’s parents, and these scores may not be as accurate as assessments performed by medical personnel, which may also affect the reliability of the conclusions drawn from the studies. According to the above study, postoperative pain in umbilical hernia repair was well managed regardless of which of the 2 local anesthetic techniques was used. Considering our study together, although we do not believe that RSB is the best method for postoperative analgesia after umbilical hernia repair, we believe that RSB is not inferior to LAI in terms of analgesia.

Compared to LAI, RSB requires an ultrasound machine and a trained anesthesiologist, which can prolong the procedure and carry the risk of hematoma, and so on. Although LAI is a classical method, it is still very useful for umbilical hernia repair. Through our study, we hope to suggest a reference for anesthesiologists that both anesthetic techniques are multimodal analgesia techniques and that anesthesiologists choose the most appropriate anesthesia strictly based on a combination of the child’s condition, time, cost, and the facilities of each medical institution.

We have some potential limitations in this study. First, our analysis was based on only 4 RCTs, and the sample sizes of all 4 studies were relatively small (n < 100). These may lead to the overestimation of treatment effects in smaller trials. More RCTs with large samples should be conducted to study this issue in a follow-up. Second, this study did not examine analgesia after 1 hour postoperatively and beyond because of limitations in the original literature data. Third, the inclusion of only English-language literature and the mention of primary outcome indicators in only a few articles in our literature may have biased the combined results. Finally, this study was not registered and approved by PROSPERO.

5. Conclusion

The findings from this systematic review and meta-analysis show that RSB and local anesthetic are effective methods for pediatric umbilical hernia repair.

Acknowledgments

We are grateful to all the participants in the research.

Author contributions

Conceptualization: Yun Zhou

Data curation: Lun-Hui Zhen and Hong-Bing Wang

Formal analysis: Lun-Hui Zhen

Investigation: Lun-Hui Zhen

Methodology: Yun Zhou

Resources: Lun-Hui Zhen

Software: Hong-Bing Wang

Supervision: Yun Zhou

Validation: Hong-Bing Wang

Visualization: Hong-Bing Wang

Writing – original draft: Lun-Hui Zhen

Writing – review & editing: Lun-Hui Zhen